Re: C60 orthorhombic structure

2021-09-24 Thread Alan Hewat
Dear Francois.
I did a quick non-exhaustive search of ICSD for pure C60, and posted the
results on https://neutronoptics.com/downloads/C60-icsd.jpg
This includes claims of tetragonal and orthorhombic structures. You can
search Google with the paper titles to find the references if you don't
have access to ICSD :-) The old neutron powder work I previously referred
to from memory was
Nature (1991) 353, 147-149 <https://www.nature.com/articles/353147a0> *Crystal
structure and bonding of ordered C60*
David, W.I.F.;Ibberson, R.M.;Matthewman, J.C.;Prassides, K.;Dennis,
T.J.S.;Hare, J.P.;Kroto, H.W.;Taylor, R.;Walton, D.R.M.
This paper is copyright by Nature, but have put ICSD details on
https://neutronoptics.com/downloads/C60-icsd_66729.jpg
<https://neutronoptics.com/downloads/C60-icsd_66729.jpg>
Below the 249K transition, the structure becomes ordered with a different
cubic phase. You will find more ISIS work on C60 with inclusion compounds,
eespecially superconducting K3C60 on
https://neutronoptics.com/downloads/K-C60-icsd.jpg including Peter
Steven's paper.
Kind Regards, Alan.

On Fri, 24 Sept 2021 at 16:18, Alan Hewat 
wrote:

> Dear Francois.
>
> Thank you for putting the paper on your private server rather than sending
> it to the whole list. However the correct link should be:
> https://perso.univ-lemans.fr/~fgouten/C60/
> Koichi KIKUCHI, et al Physiea C 185-189 (1991) 415-416
> STRUCTURE AND SUPERCONDUCTIVITY OF SINGLE CRYSTALLINE C80
> There are quite a number of papers on C60 superconductors, in particular
> by Bill David and colleagues at ISIS, and it would be worthwhile doing a
> broader search of the literature.
>
> Kind regards, Alan.
>
> On Fri, 24 Sept 2021 at 14:56, francois Goutenoire <
> francois.gouteno...@univ-lemans.fr> wrote:
>
>> Dear Rietveld users,
>>
>> Sorry for the mistake, the paper was published in 1991.
>>
>> I put the paper in the link
>>
>> http:\\perso.univ-lemans.fr\~fgouten\C60
>>
>> From the previous answer it seems that it is not really realiable.
>>
>> Best wishes françois Goutenoire
>>
>>
>> Le 24/09/2021 à 12:05, francois Goutenoire a écrit :
>>
>> Dear Rietveld users,
>>
>> We are currently looking for the atomic structure (cif file) of the C60
>> Orthorhombic cell
>>
>> The previous paper : "Structure and superconductivity of single
>> crystalline C60" from Koichi Kikuchi et al.
>>
>> Physica C in 1975
>>
>> The cell parameters are given  a=25.011 Ang, b=25.582 Ang. c=10.003 Ang.
>> Space group Pbnm
>>
>> but there is not atomic position in the paper.
>>
>> Best regards, françois Goutenoire
>>
>>
>> ++
>> Please do NOT attach files to the whole list  
>> 
>> Send commands to   eg: HELP as the subject 
>> with no body text
>> The Rietveld_L list archive is on 
>> http://www.mail-archive.com/rietveld_l@ill.fr/
>> ++
>>
>>
>> --
>> *
>> Pr. Francois GOUTENOIRE
>> e-mail: francois.gouteno...@univ-lemans.fr
>> Tel: 02.43.83.33.54
>> FAX: 02.43.83.35.06
>> Skype Entreprise visio conférence
>> Département des Oxydes et Fluorures
>> Institut des Molécules et des Matériaux du Mans
>> IMMM - UMR CNRS 6283
>> Université du Maine - Avenue Olivier Messiaen
>> F-72085 Le Mans Cedex 9
>> FRANCE
>> *
>> Formation Rietveld CNRS 
>> 2020https://cnrsformation.cnrs.fr/diffraction-des-rayons-x-sur-materiaux-polycristallins?axe=135
>> Formation EDX CNRS 
>> 2020https://cnrsformation.cnrs.fr/fluorescence-x-edx?axe=135
>> Formation SAXS et Réflectivités pour couches minces et matériaux 
>> nanostructurés.https://cnrsformation.cnrs.fr/caracterisation-des-materiaux-nanostructures-par-diffusion-des-rayons-x?axe=135
>> Bibliographiehttps://scholar.google.fr/citations?hl=fr=qC-lmN4J_op=list_works=1=titlehttps://orcid.org/-0001-5339-3002
>>
>> ++
>> Please do NOT attach files to the whole list > >
>> Send commands to  eg: HELP as the subject with no body
>> text
>> The Rietveld_L list archive is on
>> http://www.mail-archive.com/rietveld_l@ill.fr/
>> ++
>>
>>
>
> --
> __
> *   Dr Alan Hewat, NeutronOpti

Re: C60 orthorhombic structure

2021-09-24 Thread Alan Hewat
Dear Francois.

Thank you for putting the paper on your private server rather than sending
it to the whole list. However the correct link should be:
https://perso.univ-lemans.fr/~fgouten/C60/
Koichi KIKUCHI, et al Physiea C 185-189 (1991) 415-416
STRUCTURE AND SUPERCONDUCTIVITY OF SINGLE CRYSTALLINE C80
There are quite a number of papers on C60 superconductors, in particular by
Bill David and colleagues at ISIS, and it would be worthwhile doing a
broader search of the literature.

Kind regards, Alan.

On Fri, 24 Sept 2021 at 14:56, francois Goutenoire <
francois.gouteno...@univ-lemans.fr> wrote:

> Dear Rietveld users,
>
> Sorry for the mistake, the paper was published in 1991.
>
> I put the paper in the link
>
> http:\\perso.univ-lemans.fr\~fgouten\C60
>
> From the previous answer it seems that it is not really realiable.
>
> Best wishes françois Goutenoire
>
>
> Le 24/09/2021 à 12:05, francois Goutenoire a écrit :
>
> Dear Rietveld users,
>
> We are currently looking for the atomic structure (cif file) of the C60
> Orthorhombic cell
>
> The previous paper : "Structure and superconductivity of single
> crystalline C60" from Koichi Kikuchi et al.
>
> Physica C in 1975
>
> The cell parameters are given  a=25.011 Ang, b=25.582 Ang. c=10.003 Ang.
> Space group Pbnm
>
> but there is not atomic position in the paper.
>
> Best regards, françois Goutenoire
>
>
> ++
> Please do NOT attach files to the whole list  
> 
> Send commands to   eg: HELP as the subject 
> with no body text
> The Rietveld_L list archive is on 
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
> --
> *
> Pr. Francois GOUTENOIRE
> e-mail: francois.gouteno...@univ-lemans.fr
> Tel: 02.43.83.33.54
> FAX: 02.43.83.35.06
> Skype Entreprise visio conférence
> Département des Oxydes et Fluorures
> Institut des Molécules et des Matériaux du Mans
> IMMM - UMR CNRS 6283
> Université du Maine - Avenue Olivier Messiaen
> F-72085 Le Mans Cedex 9
> FRANCE
> *
> Formation Rietveld CNRS 
> 2020https://cnrsformation.cnrs.fr/diffraction-des-rayons-x-sur-materiaux-polycristallins?axe=135
> Formation EDX CNRS 
> 2020https://cnrsformation.cnrs.fr/fluorescence-x-edx?axe=135
> Formation SAXS et Réflectivités pour couches minces et matériaux 
> nanostructurés.https://cnrsformation.cnrs.fr/caracterisation-des-materiaux-nanostructures-par-diffusion-des-rayons-x?axe=135
> Bibliographiehttps://scholar.google.fr/citations?hl=fr=qC-lmN4J_op=list_works=1=titlehttps://orcid.org/-0001-5339-3002
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat TVA FR 79499450856
__
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Fwd: PRogram Faults

2020-10-23 Thread Alan Hewat
__
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
   from my telephone
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__

-- Forwarded message -
From: Radovan Cerny 
Date: Fri, 23 Oct 2020, 09:43
Subject: RE: PRogram Faults
To: Susana Conconi , rietveld_l-requ...@ill.fr



Dear Susana,



The best is to get into the contact with Montserrat Casa Cabanas



https://cicenergigune.com/en/montserrat-casas-cabanas/presentation



Radovan





Radovan Cerny

Laboratoire de Cristallographie, DQMP

Université de Genève

24, quai Ernest-Ansermet

CH-1211 Geneva 4, Switzerland

Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08

mailto : radovan.ce...@unige.ch

URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm



*De :* rietveld_l-requ...@ill.fr  *De la part de*
Susana Conconi
*Envoyé :* jeudi 22 octobre 2020 20:56
*À :* rietveld_l-requ...@ill.fr
*Objet :* PRogram Faults



Dear all



I would like to connect with someone who uses the Faults program  (Fullprof
suite) to apply it on clay minerals .

Best regards



Susana Conconi

CETMIC (Centro de Tecnologìa de Recursos Minerales y Ceràmica )

M.B. Gonnet

Argentina
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Re: Integrated intensities issue.

2020-04-22 Thread Alan Hewat
In general no. In the extreme case a single crystal would have reflections
that were never exited or reached the detector.
__
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
   from my telephone
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__

On Wed, 22 Apr 2020, 14:19 Shay Tirosh,  wrote:

> Dear Rietvelders
>
> I hope you all feeling well and surviving the Coronavirus.
>
> Does the integrated intensity corresponding to a reflection peaks of
> oriented material and randomly oriented are the same? Please note in bough
> case the volume fraction of the material is the same, Only the orientation
> is not.
>
>
> Thanks
>
> Shay
>
> --
> _
>
> Dr. Shay Tirosh
> Institute for Nanotechnology & Advanced Materials
> Bar Ilan University
> Ramat Gan, 52900
> Israel
> Phone: +972-(0)30-531-7320
> Mobile: +972-(0)54-8834533
> Email: stiro...@gmail.com
> _
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
++
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Re: GSAS-II - indexing TOF data

2020-04-14 Thread Alan Hewat
Hi Bob and Toby. Hope you are keeping safe. It would be good if you and
others could send your replies to queries such as Alex's to the whole list,
rather than just to him. I'm sure other people could benefit from your
expertise.

Best wishes to all Rietvelders. Alan.
__
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
   from my telephone
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__

On Tue, 14 Apr 2020, 11:20 Alexandros Lappas,  wrote:

> Dear Bob,
>
>
>
> I have followed your suggestions and I can now run the auto-indexing by
> having read a list of d-spacings, mainly with reflections selected from the
> lower angle scattering banks.
>
>
>
> Thank you.
>
> Alex
>
>
>
> --
>
> Dr. Alexandros Lappas,
>
> Research Director,
>
> Institute of Electronic Structure and Laser (IESL),
>
> Foundation for Research and Technology - Hellas (FORTH),
>
> P.O. Box 1385, Vassilika Vouton,
>
> 711 10 Heraklion, Crete,
>
> GREECE
>
>
>
> Tel   +30 2810 391344
>
> Fax   +30 2810 391305
>
> Quantum Materials & Magnetism Lab
> <https://www.iesl.forth.gr/en/research/magnetic-materials>
>
> --
>
>
>
> *From:* Von Dreele, Robert B. [mailto:vondre...@anl.gov]
> *Sent:* 14 April 2020 07:02
> *To:* Toby, Brian H. ; lap...@iesl.forth.gr
> *Cc:* rietveld_l@ill.fr
> *Subject:* RE: GSAS-II - indexing TOF data
>
>
>
> Dear Alex,
>
> When you have created your peaklist: just a list of d-spacings will do
> (not TOF) – order doesn’t matter; you can read them as a PKS histogram via
> the Data/Read Powder Pattern Peaks. The result will have a Unit Cell List
> for running the indexing routines. This is how the indexing routines were
> originally tested using the NBS 25 publication of d & I for a wide variety
> of substances all based on lab powder data. It is vital for indexing that
> you have the lowest order reflections – commonly difficult to get from TOF
> instruments. Avoid using very short d-spacing reflections; they hinder the
> indexing process. Use the 20-30 longest d-spacing reflections only.
>
> Best,
>
> Bob Von Dreele
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> *From: *Toby, Brian H. 
> *Sent: *Monday, April 13, 2020 7:32 PM
> *To: *lap...@iesl.forth.gr
> *Cc: *rietveld_l@ill.fr; Von Dreele, Robert B. 
> *Subject: *Re: GSAS-II - indexing TOF data
>
>
>
> Alex,
>
>
>
> We do not have a routine that will merge peaks from multiple histograms,
> but you can use “Save peaks” on each histogram to obtain the files for
> each. Them manually edit them to create a composite file which can be read
> in and then used for indexing.
>
>
>
> Brian
>
>
>
> On Apr 13, 2020, at 1:24 PM, Alexandros Lappas 
> wrote:
>
>
>
> Dear colleagues,
>
>
>
> We are working on some neutron time-of-flight (TOF) data and attempt to
> index them within GSAS-II.
>
>
>
> As the low-angle detector banks contain information that is not resolved
> by the higher angle banks, data indexing is not thorough.
>
>
>
> Could you please advise whether it is possible to combine “Peak List”
> information from individual detector banks with the purpose to create an
> “Index Peak List” that contains a more exhaustive set of reflections for
> indexing purposes within GSAS-II?
>
>
>
> If this is not possible within GSAS-II, could you please suggest an
> alternative ‘auto-indexing’ suite that may be able to handle TOF neutron
> data?
>
>
>
> Thank you.
>
> Alex Lappas
>
>
>
> --
>
> Dr. Alexandros Lappas,
>
> Research Director,
>
> Institute of Electronic Structure and Laser (IESL),
>
> Foundation for Research and Technology - Hellas (FORTH),
>
> P.O. Box 1385, Vassilika Vouton,
>
> 711 10 Heraklion, Crete,
>
> GREECE
>
>
>
> Tel   +30 2810 391344
>
> Fax   +30 2810 391305
>
> Quantum Materials & Magnetism Lab
> <https://www.iesl.forth.gr/en/research/magnetic-materials>
>
> --
>
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.co

Magnetic-structure sessions at the IUCr Congress in Prague (22-30 August 2020)

2020-03-02 Thread Alan Hewat
Dear Colleagues,

The 2020 IUCr Congress in Praha (www.iucr25.org) will be must-attend
meeting for researchers involved in the determination and application of
high-quality magnetic-structures. We’ll have broad representation from
research groups around the world doing high-impact science. Abstracts are
due by 31 Mar 2020. We encourage you make this meeting a priority! A
sampling of the microsymposia and keynote lectures relevant to magnetic
structures are listed below. The program, which includes over 100 half-day
microsymposia and 36 keynote lectures, will also offer extensive coverage
of related topics such as total scattering, frustration and disorder,
modulated structures, quasicrystals, mineral structures, theoretical
crystallography, quantum crystallography, topological materials, electronic
and quantum materials, functional materials, energy materials,
high-pressure crystallography, powder diffraction, x-ray and neutron
diffraction, electron diffraction, 3D/4D electron crystallography, cryo-EM,
XFEL sources, and many others. See the full program for details.

Sincerely, The IUCr Commission on Magnetic Structures: http://magcryst.org
(Mois I. Aroyo, Maxim Avdeev, Branton J. Campbell, Javier Campo, M. Teresa
Fernandez-Diaz, Ovidu Garlea, Margarida Henriques, Danny Litvin, J. Manuel
Perez-Mato, Alexander Pirogov, Juan Rodriguez-Carvajal, Taku J. Sato,
Wieslawa Sikora, Andrew Wills, Oksana Zaharko)

** Sample of related Keynote lectures*

*The science of symmetry breaking *(KN-35, Sat 29 AM)

Keynote speaker: Stokes Harold

*Quantum crystallography and spintronic materials *(KN-15, Tue 25 AM)

Keynote speaker: Macchi Piero

*Structural flexibility and disorder in functional materials *(KN-3, Sun 23
AM)

Keynote speaker: Andrew Goodwin

** Sample of related Microsymposia:*

*Topological magnetic order and quasiparticles *(MS-87, Fri 28 PM)

Chairs: Avadh Behari Saxena, Katherine Pappas

*Magnetic structures at extreme conditions and in extreme samples *(MS-61,
Thu 27 AM)

Chairs: Angel Arevalo-Lopez, Andrzej Katrusiak

Invited speakers: Elena Solana-Madruga, Dawid Pinkowicz

*Symmetry aspects of magnetic order and magnetic properties *(MS-68, Thu 27
PM)

Chairs: Margarida Henriques, Mois I. Aroyo

Invited speakers: Laura Chaix, Navid Qureshi

*Frustrated magnetic order and emerging science *(MS-45, Wed 26 AM)

Chairs: Romain Sibille, Geetha Balakrishnan

Invited speakers: Ketty Beauvois, Nicolas Gauthier

*Molecular magnets and metal-organic frameworks including quantum
crystallography approaches*

(MS-51, Wed 26 PM)

Chairs: Veronica Paredes, Jozef Kozisek

Invited speakers: Guillermo Minguez Espallargas, Ivan Nemec

*Structural, electronic and magnetic ordering: from fundamental physics to
functionality*

(MS-38, Tue 25 AM)

Chairs: Ovidiu Garlea, Javier Sanchez Benites

Invited speakers: Steve Nagler, Paula Kayser

*Phase transitions in complex materials: structure and magnetism *(MS-101,
Sat 29 PM)

Chairs: Yuichi Shimakawa, Alexandra Gibbs

Invited speakers: Patrick Woodward, Midori Amano Patino

*New applications of coherent scattering *(MS-40, Tue 25 AM)

Chairs: Ian Robinson, Christian Gutt

Invited speakers: Johanned Ihli, Foivos Perakis

*Total scattering *(MS-37, Tue 25 AM)

Chairs: Pierre Bordet, Emil Bozin

Invited speakers: Stephan Rosenkranz, Bo Iversen

*Perovskites *(MS-14, 23 Sun PM)

Chairs: Chris Ling, Philip Lightfoot

Invited speakers: James Rondinelli, Joke Hadermann
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat TVA FR 79499450856
__
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Re: Job offer

2020-02-21 Thread Alan Hewat
Yes, of course Luca.

Best wishes Alan
__
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
   from my telephone
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__

On Fri, 21 Feb 2020, 23:57 Luca Gelisio,  wrote:

> Hello,
>
> Can I post a job offer which might be of interest for the community?
>
> Thanks a lot and best regards,
> luca
>
> ++
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> text
> The Rietveld_L list archive is on
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> ++
>
>
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Re: RE: Software re-binned PD data

2019-09-27 Thread Alan Hewat
Tony. If you want the statistics to be the same as for larger steps you
should be adding the counts from your PSD channels, not averaging them.
That said, with an x-ray PSD you perhaps have so much intensity that
uncertainties in your refined parameters due to counting statistics may be
small compared to systematic errors, so it may not be important that your
PSD averages adjacent channels instead of summing them. Perhaps the PSD
manufacturer chose averaging to make the data look better:-)
Alan.

On Fri, 27 Sep 2019 at 07:45, iangie  wrote:

> Dear Rietvelders,
>
> Thanks for your opinions!
> The "re-binning" of 1D data was done by my measurement software
> automatically, rather than by analysis software.
> The CPS is unchanged after its "re-binning". This means, rather than
> adding counts of neighboring steps, it is *averaging* my data (sum counts
> up then divided by the number of combined bins)!
> I have a feeling what my measurement software doing is not correct...
>
> --
> *Dr. Xiaodong (Tony) Wang*
> *Research Infrastructure Specialist (XRD)*
> Central Analytical Research Facility (CARF)   |   Institute for Future
> Environments
> Queensland University of Technology
>
>
> 在 2019-09-27 10:31:45,alancoe...@bigpond.com 写道:
>
> Hi Tony
>
>
>
> >My I ask is this re-bined data from the measurement software considered
> as "raw data" or "treated data"?
>
>
>
> I’m not sure what is meant by treated data. Almost all neutron data and
> synchrotron data with area detectors are “treated data”.
>
>
>
> If the detector has a slit width in the equatorial plane that is 0.03
> degrees 2Th then it makes little sense using a step size that is less than
> 0.03/2 degrees 2Th. If rebinning is done correctly (see rebin_with_dx_of in
> the Technical Reference) then rebinning is basically collecting redoing the
> experiment with a wider slit.
>
>
>
> In the case of your PSD then the resolution of the PSD would be the
> smallest slit width. If the data has broad features relative to the slit
> width then rebinning (or using a bigger slit width) should not change the
> results. You could simulate all this using TOPAS to see the difference.
> Correct rebinning should not affect parameter errors.
>
>
>
> This is a question that is not simple to answer and if there’s concern
> then:
>
>
>
>1. Simulating data with the small step size and performing a fit
>2. And then rebinning with various slit widths and then fitting
>3. And then comparing parameters errors and parameter values for all
>the refinements should shine light on the area.
>
>
>
> I don’t know where but I feeling is that there should be papers on this.
>
>
>
> Cheers
>
> Alan
>
>
>
>
>
> *From:* rietveld_l-requ...@ill.fr  *On Behalf
> Of *iangie
> *Sent:* Thursday, September 26, 2019 1:40 PM
> *To:* rietveld_l@ill.fr
> *Subject:* Software re-binned PD data
>
>
>
> Dear Rietvelder,
>
>
>
> I hope you are doing well.
>
> It is generally acknolwdged that Rietveld refinement should be performed
> on raw data, without any data processing.
> One of our diffractometer/PSD  scans data at its minimal step size (users
> can see that the step size during scan is much smaller than what was set),
> and upon finishing, the measurement software re-bin the counts to the step
> size what users set (so the data also looks smoother, after re-bin).
> My I ask is this re-bined data from the measurement software considered as
> "raw data" or "treated data"? And can we apply Rietveld refinement on this
> data?
>
>
>
> Any comments are welcome. :)
>
> --
>
> *Dr. Xiaodong (Tony) Wang*
>
> *Research Infrastructure Specialist (XRD)*
>
> Central Analytical Research Facility (CARF)   |   Institute for Future
> Environments
>
> Queensland University of Technology
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
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Re: Software re-binned PD data

2019-09-26 Thread Alan Hewat
Tony, if you bin (add) the raw data you can perform Rietveld refinement as
if you had taken larger steps.
Regards, Alan.

On Thu, 26 Sep 2019 at 05:42, iangie  wrote:

> Dear Rietvelder,
>
> I hope you are doing well.
> It is generally acknolwdged that Rietveld refinement should be performed
> on raw data, without any data processing.
> One of our diffractometer/PSD  scans data at its minimal step size (users
> can see that the step size during scan is much smaller than what was set),
> and upon finishing, the measurement software re-bin the counts to the step
> size what users set (so the data also looks smoother, after re-bin).
> My I ask is this re-bined data from the measurement software considered as
> "raw data" or "treated data"? And can we apply Rietveld refinement on this
> data?
>
> Any comments are welcome. :)
>
> --
> *Dr. Xiaodong (Tony) Wang*
> *Research Infrastructure Specialist (XRD)*
> Central Analytical Research Facility (CARF)   |   Institute for Future
> Environments
> Queensland University of Technology
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++++++
>
>

-- 
__
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 +33.476.98.41.68
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Re: Simultaneous refinement of multiple atoms sharing same site

2019-09-01 Thread Alan Hewat
Even with neutron diffraction :-) you can only refine the scattering power
(length) of each site. When you refine the occupancy of two atoms on a
single site you are adding additional "information" by assuming that the
site is fully occupied by one or the other. That may be true, or not. If
the scattering power changes significantly with wavelength (or angle with
x-rays) you may obtain the necessary additional information.

But can you do a chemical or other quantitative analysis to determine the
relative proportions of eg cations ? Neutron activation analysis may also
be possible. Don't believe that everything can be determined by powder
diffraction :-)

Alan
______
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
   from my telephone
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__

On Sat, 31 Aug 2019, 19:59 Larry Finger,  wrote:

> On 8/31/19 9:44 AM, Ahmed Subrati wrote:
> > Dear all,
> >
> > I wanted to ask how three atoms, sharing the same xyz position, could be
> refined
> > in terms of their occupancies /via /FullProf. We know that for the case
> of two
> > atoms, the first atom is set as 11.0 and the second one as -11.0 so that
> their
> > sum is unity, but how would be the case for three atoms.
>
> It does not matter what program you use. If you have X-ray data, and were
> to
> normalize the scattering curve for each type of atom by dividing by the
> atomic
> number, the curves would very nearly overlap. The minute differences would
> be
> the only information allowing you to determine those occupancies uniquely.
> If
> you merely constrain the sum of the occupancies, and the composition of
> the
> sample, the results will converge to nonsense results because the errors
> in the
> data would overwhelm those small differences.
>
> If you had neutron scattering data, then you might be able to do it,
> depending
> on how different the scattering for the 3 types of nuclei.
>
> Your only possibility is to add additional constraints. Perhaps average
> bond
> lengths will provide such information, or there may be other information
> available for your material. In any case, the diffraction data will not be
> sufficient for Reitveld, or single-crystal data.
>
> Larry
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
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Fwd: Joint ESRF – ISTerre PhD Thesis Studentship

2019-07-16 Thread Alan Hewat
-- Forwarded message -
From: Bernd Hinrichsen 
Date: Tue, 16 Jul 2019 at 09:59
Subject: Joint ESRF – ISTerre PhD Thesis Studentship
To: rietveld_l-requ...@ill.fr 


Was just sent this by a colleague and think it might be of interest to one
or other reader:



http://cristallografia.org/uploaded/7620.pdf



Beware! Very close deadline: August 3rd.



Greetings,

Bernd Hinrichsen
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-- 
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 +33.476.98.41.68
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The passing of Massimo Merezio

2019-05-15 Thread Alan Hewat
My colleagues at the CNRS/CEA in Grenoble (Catherine Bougerol, Jean-Louis
Hodeau...) have told me the sad news of the passing of Massimo Marezio in
Rome on Monday 13th May. Massimo was recruited from Bell labs to lead the
Grenoble CNRS crystallography by Académicien Felix Bertaut. He made many
important contributions to solid state chemistry and crystallography
including powder diffraction, and trained many of today's leading
scientists in the US and Europe. I once described him as "the best
scientist with whom I had ever worked". His former colleagues plan a
commemoration and an account of his exceptional contributions.
Alan
__
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 +33.476.98.41.68
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Re: Powdll v2.60

2018-11-02 Thread Alan Hewat
OK thanks David. Perhaps write to the author. Version 2.76 installs and
runs under 64-bit Windows-10. Alan


>From my mobile phone:
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat


>
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Re: Powdll v2.60

2018-11-02 Thread Alan Hewat
Google finds the latest version of Powdll is 2.76, which you can download
from http://users.uoi.gr/nkourkou/powdll/

Otherwise I am not familiar with this application. Alan.

On Fri, 2 Nov 2018 at 10:04, DAVID MARTINEZ BLANCO 
wrote:

> Dear Colleagues,
>
>
>
> I need urgently the versión 2.60 of the program Powdll for converted xrd
> files. I tried to download from oficial webpage but its link is disabled.
>
> Thanks in advance and best wishes.
>
> David
>
>
>
> Dr. David Martínez Blanco
>
> Técnico de Difracción de Rayos X
>
> Servicios Científico-Técnicos
>
> Universidad de Oviedo
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
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Re: Rietveld website cancelled ?

2018-08-30 Thread Alan Hewat
Thanks Armel. Have a look also at the s-triazine paper. 30 years ago Pawley
and I were determining  structures of materials that are liquid at room
temperature. I remember he was worried about liquid HCN on the French
train. You might try that :-)

>From my mobile phone:
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat

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Re: Rietveld website cancelled ?

2018-08-30 Thread Alan Hewat
> You dig !
Please stop digging Armel. Loaded guns, grave digging and religion are off
limits.
__
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 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld website cancelled ?

2018-08-29 Thread Alan Hewat
> A clear distinction having my complete agreement. (Armel)
Ouf. Nous sommes d'accord enfin :-) For Armel, here are a couple of examples
<https://scholar.google.com/scholar?hl=en_sdt=0%2C5=author%3A%22GS+Pawley%22+author%3A%22AW+Hewat%22+=>
of automatic indexing, search-match and structure DETERMINATION from
neutron powder data. Very few citations though; crystallographers largely
ignored neutron powder diffraction before 1987 and Hi-Tc :-)
__
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Re: Rietveld website cancelled ?

2018-08-28 Thread Alan Hewat
Good work Armel. Note that little is lost once it is posted to the WWW,
since it is backed up in several places. The "WayBack Machine" is a good
way of recovering historic web sites. The WayBack server is a bit slow,
since it is supported only by donations and is probably in heavy demand -
see:
https://web.archive.org/web/20180212154506/http://home.wxs.nl/~rietv025/

On Tue, 28 Aug 2018 at 17:15, Le Bail Armel  wrote:

>
>
> http://home.wxs.nl/~rietv025/
>
> It has suddenly disappeared a few days ago.
>
>
>
> A copy can be found here :
>
> http://www.cristal.org/rietv025/
>
>
>
> Armel
>
>
>
>
>
>
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++++++
>
>

-- 
__
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Re: Rietveld

2018-08-22 Thread Alan Hewat
*>  Argh ! Shame on us three ! *
Yes, we went too far. Sorry Armel. But Robert only has to read the footer
at the bottom of every post to find how to remove himself.
__
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Re: Rietveld

2018-08-22 Thread Alan Hewat
*> Another example.. Loopstra, van Laar and Breed Physics Letters 26A(11)
1968, 526* (AleB)

Examples are easy. In Gibaud, Le Bail and Bulou
<http://iopscience.iop.org/article/10.1088/0022-3719/19/24/007/meta> J.
Phys. C: Solid State Phys. 19 (1986) 4623
"*...the Rietveld program modified by Le Bail (1985)*" is used to refine
data collected at ILL on D1A (Hewat & Bailey 1976
<https://www.sciencedirect.com/science/article/pii/0029554X76904699>)
without citing either Rietveld or the people who built the diffractometer,
helped with the data collection, and supplied the 1972 Rietveld code
<http://www.ccp14.ac.uk/ccp/web-mirrors/hewat-rietveld/index.html>.
______
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 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld

2018-08-22 Thread Alan Hewat
Leonid. Rietveld's code is indeed a specific type of profile refinement.
Structure parameters are refined to fit the observed profile intensities
using a least squares code similar to that used to fit integrated Bragg
intensities at Oak Ridge - ORFLS (1962). From 1961 profile refinement
methods were used at Argonne to fit multiple peaks to profile intensities,
and later at Petten. All references are given in  vL
<http://journals.iucr.org/a/issues/2018/02/00/ib5058/>.

Unfortunately, the term "Rietveld method" has been applied to types of
profile refinement that are closer to earlier profile refinement methods,
such as refining the proportions of different phases where the individual
structures are known.

That is why I prefer to use Rietveld's original term "profile refinement"
for all kinds of powder pattern refinement, and reference Loopstra and
Rietveld (1969) instead of just Rietveld (1969). I would also call
quantitative phase analysis from powders "profile refinement" rather than
Rietveld refinement, and reference Werner et al. (1979).
______
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
  from my tablet
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld

2018-08-21 Thread Alan Hewat
*>   credit should be given to Rietveld for developing and distributing his
software *
No-one is disputing that, even if Rietveld himself never gave credit to
anyone else. In Rietveld (1969) he merely `*thanks Drs B. O. Loopstra and
B. van Laar for their suggestions and helpful criticism*'. Yet according to
vL <http://journals.iucr.org/a/issues/2018/02/00/ib5058/> he had been
hired as a postdoc to contribute to a problem they had been working on..
His home page <http://home.wxs.nl/~rietv025/> is an extreme example, where
others are only credited for their hommage to him.

Gauss and Legendre's work shows that science is not performed by
individuals in a vacuum.
*Now we call it "Least Squares Refinement" and not "Gauss Refinement".*
______
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 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld

2018-08-21 Thread Alan Hewat
Scott. If for commercial reasons you don't wish to disclose the details of
Panalytical's code,  I suggest you reference "code based on the Rietveld
code - Rietveld (1969) Reactor Centrum Nederland Report RCN-104 (which
contains the original code).  My version is on:
http://www.ccp14.ac.uk/ccp/web-mirrors/hewat-rietveld/
__
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http://www.NeutronOptics.com/hewat
__
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Re: Rietveld

2018-08-21 Thread Alan Hewat
Scott. If you use the code distributed by Rietveld, you should certainly
acknowledge it as "the Rietveld program/code" as I did in my Harwell
report  1973_The_Rietveld_Program_for_the_Profile_Refinement_of_
Neutron_Diffraction_Powder_Patterns_AERE_R7350-von_Dreele_annotations.pdf
<http://hewat.net/science/papers/1973_The_Rietveld_Program_for_the_Profile_Refinement_of_%20Neutron_Diffraction_Powder_Patterns_AERE_R7350-von_Dreele_annotations.pdf>


In that case you should also list the actual code you use, as I did. Alan.

On Tue, 21 Aug 2018 at 20:36, Scott Speakman 
wrote:

> It is interesting to read this conversation and to hear the various points
> of view.
>
>
>
> I have one point for consideration to add, and would love to hear the
> opinion of those who were more closely involved in those early days:  I was
> always under the impression that the nomenclature "Rietveld technique"
> evolved mostly because Hugo Rietveld freely distributed the programming
> code for others to use, and allowed the code to be used and incorporated
> into other programs without ever requesting licensing fees or the like.  In
> that case, the name "Rietveld technique" isn't used to credit the
> inventor(s) of the methodology, but rather to acknowledge the author of the
> original programming code.
>
>
>
>
>
>
> Kind Regards,
>
>
> *Scott A Speakman, Ph.D. *Principal Scientist- XRD
>
__
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Re: Rietveld

2018-08-21 Thread Alan Hewat
*> As a matter of course we didn't took part in the discussi**on... *
(Schenk)
*> ...**people pretending now to speak in place **of Loopstra should stop
to do so *(Le Bail)
What a contrast of style and substance. Late believers are true believers,
and Passion evicts Doubt.

Seeking sanity, I refer back to Miguel and the meaning of truth and
knowledge.:
> *Scientists cannot ask anyone for the absolute truth*  (A consideration
valid for one but also for two)
By absolute <https://www.google.fr/search?q=absolute> truth I meant
universal or divine truth. We can certainly ask everyone for the complete
truth as they perceive it - opinion, the first kind of knowledge according
to the Dutch philosopher <http://ethicadb.org/241>, and "the only source of
falsity" :-) Scientists try to approach the second kind of knowledge
(reason). The third kind is divine truth, and even Armel cannot ask for
that.

On Tue, 21 Aug 2018 at 17:44, Le Bail Armel  wrote:

> Dear Rietvelders,
>
>
>
> The last sentence of the van Laar & Schenk paper is  :
>
> "It seems to us justified to replace the name ‘Rietveld method’
> in the future by the working title of the past: ‘profile method,’
> or to honour the inventor by using ‘Loopstra method’."
>
> So, shame on Rietveld for having stolen Loopstra idea and mathematics
> from van Laar. Shame also for having modified a paper from Henk Schenk
> telling early the "true."
>
> Thanks to Bob van Laar for being so obviously modest and not
> considering that his mathematics matter in the method.
>
> Hope that among the 700 readers there are a few like me finding
> that paper completely incoherent and not convincing at all.
>
> The fact is that Hugo Rietveld was convinced that he was the
> main conceiver of the method and it is absolutely not impossible
> that Loopstra was only one of the numerous guys who had the idea
> tor fit a complete powder pattern instead of extracted intensities.
> Rietveld himself could be one of such guys. He decided to thank
>
> Loopstra and van Laar "for their suggestions and helpful criticisms".
>
> And this supposes that Loopsta and van Laar have very probably
>
> read the paper before submission and seen clearly that Rietveld
>
> was the only author of that now most cited 1969 paper...
>
> One of the main surprising sentence in the paper is :
> "If the community had awarded this (Loopstra & Rietveld, 1969)
> paper the recognition it deserved, the described profile refinement
> method would probably not be named after Rietveld alone. From the
> point of view of historical correctness this would have been much
> closer to the truth."
>
> Indeed, in that 1969 paper one can find :
> "In neutron powder diffraction, it is customary to use as
> least-squares data the integrated values of the diffraction peaks,
> even when these consist of more than one Bragg reflexion. The loss
> of information inherent in this technique can, however, be eliminated
> by using the complete observed powder pattern in a direct manner
> (Rietveld, 1967). This method determines the esti-mates of the
> structure parameters by finding a least-squares fit between the
> observed and calculated profile intensities."
>
> So, Loopstra cosigns a paper in 1969 with Rietveld in which he
> recognizes using the Rietveld method as described in the Rietveld
> 1967 paper !
>
> Later Loopstra published many papers referencing the Rietveld
> 1969 paper.
>
> My conclusion is that people pretending now to speak in place
> of Loopstra should stop to do so.
>
> Best,
>
> Armel Le Bail
>
>
> > Message du 21/08/18 16:01
> > De : h.sch...@uva.nl
> > A : Rietveld_l@ill.fr
> > Copie à :
> > Objet : [SUSPECTED SPAM] Rietveld
> >
> >We were worried that our article was not reaching the powder
> crystallographers as it was published, although Open Access, in Acta Cryst
> A. Jim Kaduk advised me to use this excellent list-server, so I became
> member and posted our message. Now I�m happy to mention that since that day
> Acta A counted almost 700 downloads for the paper, so we clearly reached
> our goal.
> >
> > I was also pleased to follow the discussion, very lively and
> interesting, and thank all contributors. The discussion was led day and
> night by our excellent chair/moderator, Alan Hewat.
> > Alan, you did a fantastic job, summarising, adding information and
> making essential links. Thank you very very much!
> >
> > As a matter of course we didn�t took part in the discussion, but now I
> like to make one comment on the question �why now�. This is a quite long
> story and carries a lot of non-scientific information. So it couldn�t b

Re: Rietveld

2018-08-20 Thread Alan Hewat
*>  For the sake of the scientific exchange of ideas and facts, too bad
that Dr. Rietveld is not alive.*
Loopstra is not alive either. Scientists cannot ask anyone for the absolute
truth. We have to look at the available evidence, and different people may
reach different conclusions. If you want the opinion of the actual people
involved, you now have van Laar's account
<http://journals.iucr.org/a/issues/2018/02/00/ib5058/>  and you have Rietveld's
account <http://home.wxs.nl/~rietv025/>.

*> ...why did this happen 49 years after?*
1) At Petten there was apparently a problem from the beginning. According
to vL <http://journals.iucr.org/a/issues/2018/02/00/ib5058/>
"*After publishing this important project alone, Rietveld found his
position in the small Petten group increasingly difficult. In 1974 he
successfully applied for the post of head of the RCN library*"
2) For the first 20 years, it simply wasn't important
"*It was only really adopted by the wider crystallographic community 20
years later, after the original small group at Petten had all left science*
".
3) When the importance of the method was finally recognised, these
reservations about its origins were published, at least in the NL - D.
Andriesse (2000), H. Schenk (2001) as quoted by vL
<http://journals.iucr.org/a/issues/2018/02/00/ib5058/>.

*Just as profile refinement "did not suddenly appear in a flash of
inspiration of a single person", questions about the origin of the method
did not suddenly appear in 2018.*

On Mon, 20 Aug 2018 at 07:35, Davide Levy  wrote:

> Hi,
>
> I am too young and out of the mainstream of powder diffraction to know all
> the stories about the born of the Rietveld Method.
>
> My question is: the article of Rietveld is published in 1969 and  the
> article about the born of this method come out after that Hugo Rietveld
> pass away, why did this happen 49 years after?
>
>
>
> *Dr. Davide Levy, Ph.D.*
>
>
> *Head of XRD laboratoryWolfson Applied Materials Research Center*
> *Tel Aviv University*
>
> *Phone: +972-3-6407815 <+972%203-640-7815>*
> *Fax:   +972-3-6407819 <+972%203-640-7819>*
> *http://www3.tau.ac.il/wamrc/  <http://www3.tau.ac.il/wamrc/>*
>
> [image:
> http://www3.tau.ac.il/wamrc/templates/labs_3/images/new-tau-logo.png][image:
> WAMRC-LOGO_new]
>
>
>
> *From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] *On
> Behalf Of *Le Bail Armel
> *Sent:* Monday, 20 August, 2018 2:22 AM
> *To:* Rietveld_l@ill.fr
> *Subject:* Re: Rietveld
>
>
>
>
>
> *>"...**the method did not suddenly appear in a flash of inspiration of a
> single person, but was the result of the work of three individuals...
> Loopstra, van Laar and Rietveld.**".*
>
>
>
> And more precisely :
>
>
>
> " HS wrote in Dutch:
>
> ‘Loopstra had the idea that it should be better to use the whole powder
> profile rather than estimated intensities to solve structures, van Laar
> worked it out mathematically and Rietveld programmed it."
>
>
>
> I conclude then :
>
> no idea for Rietveld and van Laar since they are from Loopstra;
>
> no mathematics for Rietveld and Loopstra;
>
> no programming for Loopstra and van Laar.
>
>
>
> A very clear result of the work of three individuals. The HS view...
>
>
>
> Seems that Rietveld had not the same opinion and claimed for ideas too and
> possibly for mathematics as well.
>
>
>
> Best,
>
>
>
> Armel
>
>
>
>
>
>
> ++++++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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++



Re: Rietveld

2018-08-19 Thread Alan Hewat
>  Seriously, HS really think that Hugo Rietveld had absolutely no idea,
and then worked out mathematically nothing ?

Armel, the vL paper
<http://journals.iucr.org/a/issues/2018/02/00/ib5058/> doesn't
say that Rietveld had no idea and contributed nothing. Please read the
first line of the paper again.

*"...the method did not suddenly appear in a flash of inspiration of a
single person, but was the result of the work of three individuals...
Loopstra, van Laar and Rietveld.".*

But it's great to see you back on the Rietveld mailing list, pushing hard
for what you Believe :-)  Alan.
______
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld

2018-08-18 Thread Alan Hewat
*> As I get older, I believe less and less in legends  (AH)*
*> ...the aristocracy of powder diffractionists is displaced (AleB)*

I don't believe in aristocracy either :-) After Bill David, Lambert van
Eijck and I published Hugo Rietveld's glowing obituary
<https://journals.iucr.org/j/issues/2016/04/00/es0421/>, I received a rough
draft of the vL paper
<http://journals.iucr.org/a/issues/2018/02/00/ib5058/>, and was frankly
shocked. But after finding that others shared those views, I suggested a
re-write of the paper to make it (perhaps) less controversial and more
historical, supported where possible with evidence from the literature.
Still, the paper seemed to address questions I myself had about the legend.

1) How could a young man, educated as a classical crystallographer (Bragg
peaks, structure factors, Fourier transforms...) produce the revolutionary
idea of simply refining the structure to fit the observed profile ? None of
the professional crystallographers I knew accepted that idea - only
physicists and chemists who used crystallography as a tool. It was a naive
physicist's approach.

2) How could Rietveld (1967) in his first paper not emphasise this
revolutionary departure from classical crystallographic techniques ? It was
almost as if he didn't consider that refining  magnetic moments and atom
displacements was real crystallography, just a refinement problem where
compromises had to be made to get a required result with an inadequate
computer.

3) Why did Rietveld leave science in 1974 if he thought that he had
achieved something remarkable ? He had a permanent job at a well funded
laboratory and a technique that would eventually revolutionise powder
diffraction. Ordinary people like me couldn't even get a job at Cambridge
(thanks Mike :-) and had to live with a succession of 3 year contracts in
foreign countries.

When I first knew Hugo, he was a modest, unassuming man, unlike Loopstra
who apparently pushed hard. When he saw that "*The response was slight, or,
rather, non-existent*" perhaps like other crystallographers for 20 years he
himself doubted the value of profile refinement.

And no I don't think the crystallographic establishment should get to name
it. Everyone knows what "profile refinement" means.

On Sat, 18 Aug 2018 at 11:29, Le Bail Armel  wrote:

> Hi,
>
>
>
> >As I get older, I believe less and less in legends. In the IUCr 1999
> issue that I cited, I should have also mentioned that there is an
> interesting article on p.4 called "*The Powder Diffraction Handicap
> <http://ww1.iucr.org/news/v7n4/7-4.pdf>*" by Armel le Bail :-)
>
>
>
> Indeed, "never say never" is verified again. The powder diffraction
> handicap (overlapping) can be considered as suppressed by XFEL
>
> https://www.xfel.eu/ where each single microcrystal of the powder
> produces 3D diffraction data, and all data are recombined !
>
> But for solving too simple problems, you will not have access to that
> overloaded machine and will have to continue to use your laboratory powder
> diffractometer and (now) classical approaches.
>
>
>
> So, once again, the aristocracy of powder diffractionists is displaced,
> this time from third generation synchrotron to XFEL, amusing, new legends
> will be built, probably.
>
>
>
> Best,
>
>
>
> Armel
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: Rietveld

2018-08-17 Thread Alan Hewat
>  ...your responsibility in establishing and approving the legend is quite
high
>  Then times to destroy the legend come, and you want to be a part of it
too, apparently.

As I get older, I believe less and less in legends. In the IUCr 1999 issue
that I cited, I should have also mentioned that there is an interesting
article on p.4 called "*The Powder Diffraction Handicap
<http://ww1.iucr.org/news/v7n4/7-4.pdf>*" by Armel le Bail :-)

I personally think we should use Rietveld's original term "Profile
Refinement", which I already used in my Harwell report
1973_The_Rietveld_Program_for_the_Profile_Refinement_of_
Neutron_Diffraction_Powder_Patterns_AERE_R7350-von_Dreele_annotations.pdf
<http://hewat.net/science/papers/1973_The_Rietveld_Program_for_the_Profile_Refinement_of_%20Neutron_Diffraction_Powder_Patterns_AERE_R7350-von_Dreele_annotations.pdf>


On Fri, 17 Aug 2018 at 10:31, Le Bail Armel  wrote:

>
>
> >Probably, that's how legends begin.
>
>
>
> Your presence on so many pictures together with Hugo Rietveld, suggests
> that your responsibility in establishing and approving the legend is quite
> high, between 30 and 60% maybe, but I recognize that Rwp is poorly
> satisfying for this fit.
>
> http://home.wxs.nl/~rietv025/crystallografen-s.jpg
>
>
>
> Then times to destroy the legend come, and you want to be a part of it
> too, apparently.
>
>
>
> Should we rename the Rietveld decomposition formula (equation 7 in his
> 1969 paper) the Loopstra decomposition formula ? I am lost.
>
>
>
> Best,
>
>
>
> Armel
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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++



Re: Rietveld

2018-08-17 Thread Alan Hewat
Armel's supervisor, Daniel Louer, made important contributions to the
description of the line shape for profile refinement with x-rays, but that
was 10 years later. His 1986 paper
<https://doi.org/10.1017/S0885715600011738> references Rietveld (1969) but
uses a different type of profile refinement developed by Sonneveld & Visser
(1975). "*The strategy consists of the refinement of different peaks in a
cluster, one at a time..."*

Daniel was eventually won over to the Petten method, and there is a nice
picture of him with Hugo at the 1999 IUCr Glasgow symposium that I
organised on "30 Years of Rietveld Refinement
<http://ww1.iucr.org/news/v7n4/7-4.pdf>" (page 7).

At my age, I prefer Googling the literature rather than relying on my
remembrances :-)

On Fri, 17 Aug 2018 at 00:22, Alan Hewat 
wrote:

> > * I remember that a Fortran version was in tests there (in Rennes in
> 1975-76), probably one of these 27 copies distributed by Hugo Rietveld
> himself to institutes all over the world.*
>
> Rietveld worked with neutron powder diffraction on magnetic and heavy
> metal oxides. An x-ray lab. in Rennes was probably not one of the selected
> 27 institutes all over the world. As Rietveld wrote in the paper you cited,
> "*The response was slight, or, rather, non-existent*", and by 1975-76 he
> had already left science. Probably, that's how legends begin.
>
> On Thu, 16 Aug 2018 at 21:05, Le Bail Armel 
> wrote:
>
>> Hi,
>>
>>
>>
>> Sorry for that blank email...
>>
>> Since times are to old stories about the Rietveld method, I first
>> heard about it in 1975-76 during my "3ème cycle" thesis in D. Grandjean
>> laboratory, Rennes, France, under the direction of D. Louër. The thesis
>> was about profile-shapes broadening due to powder small grain size.
>> http://www.cristal.org/rapport/Le-Bail-These-3eme-Cycle.pdf
>>
>> I did not use the Rietveld method at that time but I remember that
>> a Fortran version was in tests there, probably one of these 27 copies
>> distributed by Hugo Rietveld himself to institutes all over the world.
>> http://home.wxs.nl/~rietv025/Rietveld%20Method.docx
>>
>> My profile shapes were quite Lorentzian and there was considerable
>> anisotropic broadening, something not yet accountable by the Rietveld
>> method at that time focused on Gaussian peak shapes.
>>
>> I was not back about the Rietveld method before the XIII IUCr Congress,
>> 1984, Hamburg, where I proposed a way to undertake such X-ray complex
>> shapes: "The Rietveld method using an experimental profile convoluted
>> by adjustable analytical function". This was the ARIT software later
>> used in 1987 for intensities extraction purposes by iterating the
>> Rietveld decomposition formula, leading to many SDPDs (Structure
>> Determination by Powder Diffractometry).
>> http://cristal.org/mespapiers-PDF/1984/1984-Rietveld-a31186.pdf
>> http://www.cristal.org/arit.html
>>
>> Best,
>>
>>
>>
>> Armel
>>
>>
>>
>> PS- Better to write your own story clearly yourself before to leave the
>> planet,
>>
>> even if nobody apparently read it.
>>
>> http://www.cristal.org/iniref/lbm-story/
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ++
>> Please do NOT attach files to the whole list > >
>> Send commands to  eg: HELP as the subject with no body
>> text
>> The Rietveld_L list archive is on
>> http://www.mail-archive.com/rietveld_l@ill.fr/
>> ++
>>
>>
>
> --
> __
> *   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
>  +33.476.98.41.68
> http://www.NeutronOptics.com/hewat
> __
>


-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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++



Re: Rietveld

2018-08-16 Thread Alan Hewat
> * I remember that a Fortran version was in tests there (in Rennes in
1975-76), probably one of these 27 copies distributed by Hugo Rietveld
himself to institutes all over the world.*

Rietveld worked with neutron powder diffraction on magnetic and heavy metal
oxides. An x-ray lab. in Rennes was probably not one of the selected 27
institutes all over the world. As Rietveld wrote in the paper you cited, "*The
response was slight, or, rather, non-existent*", and by 1975-76 he had
already left science. Probably, that's how legends begin.

On Thu, 16 Aug 2018 at 21:05, Le Bail Armel  wrote:

> Hi,
>
>
>
> Sorry for that blank email...
>
> Since times are to old stories about the Rietveld method, I first
> heard about it in 1975-76 during my "3ème cycle" thesis in D. Grandjean
> laboratory, Rennes, France, under the direction of D. Louër. The thesis
> was about profile-shapes broadening due to powder small grain size.
> http://www.cristal.org/rapport/Le-Bail-These-3eme-Cycle.pdf
>
> I did not use the Rietveld method at that time but I remember that
> a Fortran version was in tests there, probably one of these 27 copies
> distributed by Hugo Rietveld himself to institutes all over the world.
> http://home.wxs.nl/~rietv025/Rietveld%20Method.docx
>
> My profile shapes were quite Lorentzian and there was considerable
> anisotropic broadening, something not yet accountable by the Rietveld
> method at that time focused on Gaussian peak shapes.
>
> I was not back about the Rietveld method before the XIII IUCr Congress,
> 1984, Hamburg, where I proposed a way to undertake such X-ray complex
> shapes: "The Rietveld method using an experimental profile convoluted
> by adjustable analytical function". This was the ARIT software later
> used in 1987 for intensities extraction purposes by iterating the
> Rietveld decomposition formula, leading to many SDPDs (Structure
> Determination by Powder Diffractometry).
> http://cristal.org/mespapiers-PDF/1984/1984-Rietveld-a31186.pdf
> http://www.cristal.org/arit.html
>
> Best,
>
>
>
> Armel
>
>
>
> PS- Better to write your own story clearly yourself before to leave the
> planet,
>
> even if nobody apparently read it.
>
> http://www.cristal.org/iniref/lbm-story/
>
>
>
>
>
>
>
>
>
>
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>

-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
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++



Re: Re:

2018-08-13 Thread Alan Hewat
It may be a question of generation, but I agree with Larry :-) Van Laar &
Schenk (2018) <http://journals.iucr.org/a/issues/2018/02/00/ib5058/> do not
say that Hugo doesn't deserve credit because "he only developed the
software". That is like waving a red flag to all of us "software
developers", and risks impassioning an otherwise interesting debate. Saying
that "before Rietveld" (yes, it risks becoming theological) Loopstra and
van Laar were weighing paper, is also provocative (and untrue). Crediting
Rietveld with the Cagliotti formulae is amusing, as is referring to him
together with Newton and Einstein.

vL wrote a paper with first hand knowledge of the time, and backed it up
from the literature. If we are going to criticise it, we have to do it just
as seriously, with references such as the Finger, Cox, and Jephcoat example
mentioned by Brian. My own understanding, which predates 1985 by more than
a decade, was that you couldn't know what code was in GSAS, simply because,
like many of the later profile refinement codes, it wasn't published (until
it was accidentally revealed :-). Instead, the Taylor (1980) code,
referenced by vL, was probably the first code that was truly independent
of Rietveld's (but depended on ORFLS). And no, Rietveld didn't invent an
intensity extraction algorithm later used by LeBail; Pawley's code predated
LeBail, and both are more related to classical ideas of peak extraction
than to Rietveld.

Rietveld certainly deserves credit for writing a beautiful program, and
publishing the code, which transformed all of powder diffraction (belatedly
for some). vL have only tried to show that "profile refinement" as
Rietveld himself called it, was the collective effort of three people. They
criticise more our community "*which had been slow to appreciate the
significance of the work in the beginning, compensated decades later by
lavish praise*".

Alan
PS It is indeed sad that Hugo is no longer with us to reply, but his web
page <http://home.wxs.nl/~rietv025/> is still there to redress the balance
(a little excessively:-)

On 14 August 2018 at 03:46, Larry Finger  wrote:
>
>
> My interpretation is not that the writer of the software should have been
> discredited, but that the other contributors should have been authors.
>
> Your example of Finger, Cox, and Jephcoat is a good one. Yes, we did stand
> on the shoulders of others, but I think we gave them credit in the
> manuscript.

__
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 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: The development of powder profile refinement...

2018-08-10 Thread Alan Hewat
Thanks Henk (and Bob). It's a story that must be quite common in science.
Humans like to simplify, and identify with heros. Humanity teaches us that
we stand on the shoulders of others. Few discoveries, especially in
science, are made by a single individual.

Profile Refinement was perhaps an idea "whose time had come" with the
application of computers. But the stroke of genius was to refine the
structure directly from the data points, rather than first refine structure
factors. Even that may have been simply because computers at that time
could only handle a limited number of parameters.

A fascinating story. Alan.

On 9 August 2018 at 12:32,  wrote:

> Bob van Laar and I wrote an article about the development of the powder
> Profile Refinement at the Reactor Centre Netherlands. This method is later
> called Rietveld refinement. We show that there were three persons involved
> in this enterprise, Bert Loopstra for the idea, Bob van Laar for the
> mathematical treatment and Hugo Rietveld for the computer program, rather
> than one. For all users of the method it will be interesting to read.
>
> The article (Acta Cryst. (2018). A74, 88-92) is Open Access and can be
> downloaded from: http://journals.iucr.org/a/issues/2018/02/00/ib5058/
> ib5058.pdf
>
> At the moment it is the most read article of Acta Cryst. A of the last 6
> months: http://178.33.252.149/a/services/mostread.html
>
> Kind greetings,
> Henk Schenk
>
______
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
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Diffraction on Energy Materials, ILL Grenoble 8 and 9 October 2018

2018-06-06 Thread Alan Hewat
Dear Rietveld_L Colleagues,


We are pleased to announce the school dedicated to *Diffraction on Energy
Materials (DiffEngMat School)* to be held in Grenoble at the Institut
Laue-Langevin *the 8 and 9 October 2018*. We invite you to visit our
website https://indico.ill.fr/EnergyMaterials for more details.

The *DiffEngMat School* will be organized as a parallel event of the ILL-ESS
User Meeting <http://www.neutrons4europe.com/> which will take place at the
Congress Center WTC (Grenoble) *from 10 to 12 October 2018*. The
participation to the *DiffEngMat School *is conditioned to the
participation in the ILL-ESS User Meeting <http://www.neutrons4europe.com/>.
A  *Diffraction on Energy Materials* *Meeting*
<http://www.neutrons4europe.com/en/events/diffraction-and-energy-materials---en/10>
will be organized as a parallel event of the ILL-ESS User Meeting
<http://www.neutrons4europe.com/>. The participants can share their ideas
in the field of Energy Materials in the framework of the proposed programme.

--

*Scientific scope of the school:*

This school aims to contribute to the training of scientists in the
application of X-ray and neutron diffraction techniques to energy materials
(battery, fuel cells, solar cells, thermoelectrics, etc.). The school
consists of selected lectures together with intensive hands-on sessions
using the advanced tools for diffraction data treatment implemented in the
FullProf Suite (including FAULTS). The school will be especially dedicated
to microstructural characterization and in-operando measurements data
analysis.

The school's participants are strongly encouraged to submit an abstract
<http://www.neutrons4europe.com/index.php?langue=en=14>
for an oral or poster presentation at the *Diffraction on Energy Materials*
*Meeting*
<http://www.neutrons4europe.com/en/events/diffraction-and-energy-materials---en/10>
.

*Lectures:*

The School consists of 2 days dedicated to acquire a general overview of
the tools needed for an efficient use of the FullProf Suite (including
FAULTS, Bond-Valence Energy Landscape calculations, etc.) at an
intermediate level with a special focus in advanced capabilities for
microstructural characterization.

*Participants:*

The School is intended for the ILL-ESS user meeting
<http://www.neutrons4europe.com/> PhD students, as well as for experienced
scientists, having a good knowledge on diffraction techniques and
crystallography, who wish to get a practical overview of the new important
developments in data analysis done in the last years. Due to logistic
requirements the maximum number of participants is limited.

*--*

Many thanks in advance for helping us in circulating this information.

Best regards,

Juan Rodriguez-Carvajal and Oscar Fabelo on behalf of the organizers

 ___

DiffEngMat - 2018

*Diffraction on Energy Materials* *School*

8-9 October 2018

ILL Grenoble, France

Email:  diffeng...@ill.eu <%20diffeng...@ill.eu>

URL: https://indico.ill.fr/EnergyMaterials
_
______
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
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--- End Message ---
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Re: Asymmetry peak shape difference between (pellet/powder)

2017-12-11 Thread Alan Hewat
; <lists...@ill.fr> eg: HELP as the subject 
> with no body text
> The Rietveld_L list archive is on 
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
>
>
> --
> *
> Pr. Francois GOUTENOIRE
> e-mail: francois.gouteno...@univ-lemans.fr
> Tel: 02.43.83.33.54 <02%2043%2083%2033%2054>
> FAX: 02.43.83.35.06 <02%2043%2083%2035%2006>
> Département des Oxydes et Fluorures
> Institut des Molécules et des Matériaux du Mans
> IMMM - UMR CNRS 6283
> Université du Maine - Avenue Olivier Messiaen
> F-72085 Le Mans Cedex 9
> FRANCE
> *
> Formation Rietveld CNRShttps://cnrsformation.cnrs.fr/stage.php?stage=18098
> Formation SAXS et Réflectivités pour couches minces et matériaux 
> nanostructurés. https://cnrsformation.cnrs.fr/stage.php?stage=18104
>
>
> ++
> Please do NOT attach files to the whole list <alan.he...@neutronoptics.com
> >
> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on http://www.mail-archive.com/
> rietveld_l@ill.fr/
> ++
>
>
>


-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
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Commercial announcements on the Rietveld list

2017-05-19 Thread Alan Hewat
People ask if commercial products can be promoted on the Rietveld list.
There are no written rules, and no vetting of posts. (Members simply risk
being suspended if they break the unwritten rules :-)

Generally, a short announcement of the availability of a commercial product
or offer is acceptable if it is in the community's interest. Overt
publicity, especially if it promotes a particular commercial product over
others, is not. As usual, announcements should be kept short, with a link
to further information.

Of course, as an independent scientist, you can still give your opinion of
the relative merits of commercial products. If in doubt, it is best to ask
first, as some members already do.

Alan.(Rietveld list manager)
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Re: TOPAS-Academic for Synchrotron and Neutron research centers

2017-05-18 Thread Alan Hewat
Alan. Perhaps you could put it this way ?

"Bruker-AXS will apply academic prices to purchases of Topaz by neutron and
synchrotron research centres​".

I have left out "generous" because it is in a company's own interest to
introduce their products to the thousands of users of such centres, who
will then hopefully buy their own copy to be able to continue refining
their data when they get back home.

Alan
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Re: Rietveld list subscription

2017-05-02 Thread Alan Hewat
>
> That means after identifying impurity phases, we should keep cell
> parameters and and all shape parameters fixed for impurity phases in
> Rietveld refinement and refine only scale factor of these phases along with
> main phase and then refine all cell parameters and and all shape parameters
> for the main phase?
>

Yes. Then you can refine the cell parameters and scale factors for the
impurity phases. Be careful not to include too many peak shape parameters -
start by constraining them to be the same for all phases.
______
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Announcement of MECA SENS 2017 and call for abstracts

2017-03-01 Thread Alan Hewat
Andrew Venter: Chair MECA SENS 2017

*Announcement of MECA SENS 2017 and call for abstracts*

Dear Colleague

The 9th International Conference on Mechanical Stress Evaluation by Neutron
and Synchrotron Radiation,*MECA SENS 2017*, invites the participation of
researchers active in the field of neutron, synchrotron and X-ray strain
scanning studies of materials. MECA SENS 2017 is hosted by the South
African Nuclear Energy Corporation (Necsa) SOC in cooperation with the
International Atomic Energy Agency.

We are pleased to announce the following prominent talks during the event:

*Alain Lodini Plenary lecture*: To be given by a Prof Philip Withers


*Keynote talks:*
· *Prof. Cev Noyan**:* *“Saint Venant’s Principle and Effect of Complex
Geometries in X-ray and Neutron Strain Analysis”*

· *Prof. Andrzej Baczmanski*:*“Diffraction methods and scale transition
model used to study evolution of the intergranular stress and micro-damage
phenomenon during elasto-plastic deformation”*

These talks will be complemented by Invited Talks within the various
conference topics by prominent international experts.


In addition we envisage holding a "Stress School" for participants new to
the field, as well as a visit to the SAFARI-1 research reactor.


The conference offers a unique opportunity to overview the most recent
developments and capabilities of the diffraction based approaches,
complemented by mechanical and image-based techniques. Equal emphasis will
be given to measurement, modelling and application of residual stress data.

We invite the participation of scientists and engineers from academia,
research facilities and industry spanning the scope from well experienced
practitioners, instrumentation experts and innovators continuously pushing
the envelope of the techniques and applications, to postgraduate students
and researchers new to this exciting field.

Manuscripts will be peer-reviewed and published in a topical international
journal.

*Important dates:*
• First call for abstracts: 01 February 2017
• Abstract submission closes: 15 March 2017
• Abstract acceptance notification: 15 April 2017
• Early bird registration: 1 May 2017
• Regular registration: 31 July 2017
• Manuscript submission: 01 September 2017
• Stress School: 18 September 2017
• MECASENS 9: 19 – 21 September 2017
• SAFARI-1 visit: 22 September 2017


*EXPRESSION OF INTEREST*
Should you be interested in attending please kindly reply to the conference
secretariat mecas...@ie.co.za

*CONFERENCE WEBSITE*
Details on the conference are available at HERE
<https://www.eiseverywhere.com/emarketing/go.php?i=currentblast=subscriberemailec=https://www.eiseverywhere.com/ehome/mecasens/487391/>,
or visiting*www.eiseverywhere.com/ehome/mecasens
<http://www.eiseverywhere.com/ehome/mecasens>*.



*Conference flyer download
<https://www.eiseverywhere.com/emarketing/go.php?i=currentblast=subscriberemailec=https://www.eiseverywhere.com/file_uploads/791f8a86429af8c43c90fd8fd6ea3a4d_MECASENSFlyer31.01.2017.pdf>CONFERENCE
REGISTRATION*
Is done via the website.

*CALL FOR ABSTRACTS*

Abstract submissions are open till 15 March 2017.


*MARKETING, SPONSORSHIP and EXHIBITION INFORMATION*

MECA SENS 2017 provides excellent opportunities to market your
organizations, products and services. We have various marketing,
sponsorship and exhibition packages available. For more information, please
refer to the MECA SENS 2017 Marketing, Sponsorship and Exhibition
Prospectus on the website or contact the conference secretariat
mecas...@ie.co.za





Andrew Venter

Section Leader: Diffraction

*Tel: *+27 (0)12 305-5038 <+27%2012%20305%205038>

*Fax: *+27 (0)12 305-5851 <+27%2012%20305%205851>

*Cell:*

*Email: andrew.ven...@necsa.co.za <http://andrew.ven...@necsa.co.za/>*

*Website:**www.necsa.co.za <http://www.necsa.co.za/>*

_____
  From my mobile telephone
 Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
<alan.he...@neutronoptics.com> +33.476.98.41.68
  http://www.NeutronOptics.com/hewat
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Re: How much COD and PDF database gives the complete known structures?

2017-01-10 Thread Alan Hewat
It depends on what you want. If you want to identify a powder pattern you
probably want to use the PDF, which may also help with the structure. If
you want to find a particular structure, you can try COD. If you are
planning a structure determination and want to be sure that it hasn't
already been done, you should use ICSD (inorganic) or CCSD (organic) if the
material contains carbon because those databases are exhaustive.

If possible use all available databases, since it is expensive to do an
experiment before doing a thorough literature search. Don't forget Google
Scholar. Don't rely on databases; use them to find the original papers -
then read them, don't just add them to your reference list.

You should also consider how the database is searched. A simple search on
the supposed formula may miss the structure described with a slightly
different formula, or may miss isomorphous structures that may be almost as
useful as the structure you require.

Alan.

On 10 January 2017 at 16:12, Shay Tirosh <stiro...@gmail.com> wrote:

> Dear retrievers
>
> I wander the followings:
> 1. How much COD and PDF overlaps?
> 2. What I am missing if I only search in COD and PDF?
>
> Are there any reviews addressing those questions ?
>
> Thank you from advance
>
> Shay
>
>
>
>
> --
> _
>
> Dr. Shay Tirosh
> Institute for Nanotechnology & Advanced Materials
> Bar Ilan University
> Ramat Gan, 52900
> Israel
> Phone: +972-(0)30-531-7320
> Mobile: +972-(0)54-8834533 <+972%2054-883-4533>
> Email: stiro...@gmail.com
> _
>
> ++
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> >
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> text
> The Rietveld_L list archive is on http://www.mail-archive.com/
> rietveld_l@ill.fr/
> ++++++
>
>
>


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__
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New Trends in Magnetic Structure Determination - Grenoble - 12 to 16 December 2016

2016-08-29 Thread Alan Hewat
I am distributing the following message to the Rietveld list on behalf of
the Workshop organisers:

Dear Colleagues,

We would like to remind you of our upcoming workshop “New Trends in
Magnetic Structure Determination”, to be held in Grenoble, at the Institute
Laue-Langevin, from 12 to 16 December 2016. We invite you to visit our
website https://indico.ill.fr/indico/event/53/ for more details and
application, which will be open until 15th September 2016.

Scientific scope:
-
This workshop aims to contribute to the training of scientists in the
treatment of neutron diffraction data for magnetic structure determination,
putting the stress in the new improved methods and tools made available in
the last years. In particular, the methods that make a combined use of
magnetic symmetry groups and representational analysis will be shown and
practiced (both for commensurate and incommensurate structures). The
workshop will be based on selected lectures together with intensive
hands-on sessions using the most popular computer programs (Isotropy
Software Suite, Bilbao Crystallographic Server, FullProf Suite, Jana2006,
etc.).

The lectures and tutorials will provide the essential tools necessary to
determine complex magnetic structures, and show the most recent
capabilities added to traditional software.

Lectures:

The Workshop consists of 5 days dedicated to acquire a general overview of
the methods of magnetic structure determination and analysis, in the frame
of the specific free software presently available. A preliminary program
can be consulted in the link below:
(https://indico.ill.fr/indico/event/53/page/3)
For the practical sessions, participants should bring their own computers
with FullProf Suite and Jana2006 already installed.

Lectures and tutorials will be presented by Juan Rodríguez-Carvajal
(Grenoble, France), J. Manuel Pérez-Mato (Bilbao, Spain), Branton J.
Campbell (Provo, USA), Laurent Chapon (Grenoble, France), Harold Stokes
(Provo, USA), Vaclav Petricek (Prague, Czech Republic) and Luis Elcoro
(Bilbao, Spain)

Participants:

The school is aimed at PhD students and experienced scientists with a good
knowledge of diffraction techniques and crystallography. As usual, among
the participants there will be a mix of different levels of experience in
using the different crystallographic tools (Isotropy Software Suite, Bilbao
Crystallographic Server, FullProf Suite, Jana2006, etc.), therefore during
this workshop both theoretical lectures and practical sessions will be
combined to ensure an optimal benefit from this workshop.
The maximum number of participants is limited, which guarantees the quality
of the given training. The selection of candidates is based on the
motivation letter and CV (plus a recommendation letter from the thesis
supervisor for PhD students). If necessary, a criterion of balance between
laboratories and countries will be applied.

Many thanks in advance for helping us in circulating this information.

Best regards,

Juan Rodríguez-Carvajal
Juan Manuel Pérez-Mato
Oscar Fabelo

P.S. we apologize if you receive this email message more than once.
 ___

NTMSD - 2016
New Trends in Magnetic Structure Determination
12-16 December 2016
ILL Grenoble, France
Email: ntmsd2...@ill.fr
URL: https://indico.ill.fr/indico/event/53
__
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Re: U,V,W cagliotti peak width parameters

2016-08-29 Thread Alan Hewat
Cagliotti shows how U,V,W are related to the collimation alpha1, alpha2,
alpha3 and mosaic spread beta of the monochromator crystal for a classical
neutron powder diffractometer; a further discussion is given here
<http://hewat.net/science/papers/1975%20Design%20for%20a%20conventional%20high-resolution%20neutron%20powder%20diffractometer.pdf>.
In general, a quadratic function of tan(theta) can be an approximate
description of how the peak width varies with scattering angle, even if an
ideal neutron diffractometer is not being used, but then U,V,W may not have
much physical meaning.
Alan.

On 29 August 2016 at 10:36, Yashwanth Padarthi <
yashwanth.padarthi...@gmail.com> wrote:

> Dear sir,
>
> Can i know what is the significance of U,V,W separately?what do they
> signify *if i have a plot of two theta Vs intensity how can one show what
> U,V,W is separately*? i have researched a lot but they are no particular
> significant meaning. i only know they depend on the instrument resolution
> function(IRF) which depends on diffractometer..
>
> Do you have any idea how U,V,W are calculated or refined?
>
> I know this formula by caglioti et al(1958)
> FWHM = (U*tan^2 theta + V*tan theta + W)^0.5
>
> but this doesn't help me knowing the real individual significance like i*n
> fullprof we can actually vary them individually *and see the changes in
> the pattern accordingly by varying U,V,W separately
>
> ++
> Please do NOT attach files to the whole list <alan.he...@neutronoptics.com
> >
> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on http://www.mail-archive.com/
> rietveld_l@ill.fr/
> ++++++
>
>
>


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Re: Something to read...

2016-08-26 Thread Alan Hewat
http://www.nature.com/articles/srep31625 on "Full Diffraction Profile
Analysis"

I like figure 1 and look forward to seeing the method applied to quantify
uncertainty by appropriately
modeling the heteroskedasticity and correlation of the error structure in
something other than silicon.

Alan
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Re: The passing of Hugo Rietveld

2016-07-28 Thread Alan Hewat
Our Rietveld list obituary for Hugo Rietveld has now been published online
by J.Appl.Cryst.
http://journals.iucr.org/j/issues/2016/04/00/es0421/index.html

Thank you for all the public and private messages of sympathy.

Alan
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The passing of Hugo Rietveld

2016-07-19 Thread Alan Hewat
d Refinement are now published every year.

Perhaps the greatest acknowledgement of Hugo’s work was his receipt of the
1995 Aminoff Prize, awarded by the Royal Swedish Academy of Sciences, Two
of us (AH and WIFD), along with Juan Rodriguez-Carvajal and Ivar Olovsson,
were there to witness Hugo, accompanied by his wife and children, receive
his accolade from the King of Sweden with typical modesty, delight and
genuine astonishment at the pervasive influence of his Method across the
sciences around the world. And beyond the world - in December 2012 he was
thrilled to receive an e-mail from David Blake of the CheMin team of the
Mars Science Laboratory rover, Curiosity, who wrote saying that *he did not
think they could have convinced NASA to send an X-ray powder diffractometer
to Mars without the Rietveld Method*.

After almost 50 years, the Rietveld Method has returned to its origins in
the Netherlands, with the third of us (LvE) completing a fast new high
resolution neutron powder diffractometer (PEARL) on the Delft reactor. Hugo
Rietveld lived to see that, and last year was the guest of honour at the
opening of this new diffractometer. He, who had been honoured throughout
the world for his achievement, was honoured in his own country by a new
generation working with neutron powder diffraction and Rietveld Refinement.

Having achieved all of that, and with a loving family and friends, he will
surely rest in peace.
Alan Hewat (AH), Bill David (WIFD) and Lambert van Eijck (LvE) July 2017
______
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++



Re: atomic position

2016-06-15 Thread Alan Hewat
>
> About Ba2TeO5, it is said that it is isomorphous with Ba2WO5 and Sr2WO5.
> Ba2WO5 belongs to the K2VO2F3 structure type...
>

 > BTW Armel, Ba2WO5 itself has been determined according to Google:

A more accessible and interesting reference is for the isomorphous Ba2ReO5:
"An investigation of the low oxidation state chemistry of rhenium in the Ba
O - Re - Re2 O7 phase diagram".
*Cheetham, A.K.;Thomas, D.M. (1987) Journal of Solid State Chemistry (1987)
71, 61-69
<http://www.sciencedirect.com/science/article/pii/0022459687901423>*

Whether or not these Pnma structures are indeed isomorphous with the
supposed P41212 structure of Ba2TeO5 is open. I assume that the information
on Ba2TeO5 comes from the PDF and is based on x-ray powder diffraction
indexing. If so, that's not a very reliable source for the stoichiometry of
heavy metal oxides. The structure of Ba2ReO5 was determined by neutron
powder diffraction.

But if we speculate as well for the other unknown, pbcn (60) Ba2TeO4, it
could be isomorphous with pnma (62) Ba2 (Cr,Si,Co) O4 and if so a neutron
structure is again available:
"Crystal structures and magnetic properties of (CrO4)(4-) containing
oxides: Sr2CrO4 ,Ba2CrO4 ,Ba3CrO5".
*Liu, G.;Greedan, J.E.;Gong, W. (1993) Journal of Solid State Chemistry
105, 78-91
<http://www.sciencedirect.com/science/article/pii/S0022459683711953>*

Whether or not any of this is useful to Rachid is doubtful. It would be
best for him to try to prepare a sample without impurity phases. The
chemistry of mixed valence heavy metal oxides is difficult enough, even
with neutron diffraction let alone x-ray powder diffraction, without having
poorly characterised impurity phases to contend with.

Alan
______
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++



Re: atomic position

2016-06-15 Thread Alan Hewat
>
> About Ba2TeO5, it is said that it is isomorphous with Ba2WO5 and Sr2WO5.
>
> Good work Armel. Yes, sharing of open databases is encouraged :-) But
> please don't attach files.
>
> BTW Armel, Ba2WO5 itself has been determined according to Google:
https://inis.iaea.org/search/searchsinglerecord.aspx?recordsFor=SingleRecord=17058181

You might like to add it to COD :-)

Alan.
______
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++



Re: atomic position

2016-06-14 Thread Alan Hewat
So far as I know (I may be wrong :-) ordered atomic positions for the two
requested compounds, with supposed formulae *Ba2TeO4 *and *Ba2TeO5*, have
not been determined. The closest I found were as I wrote: *"Sr Te O6 and Ba
Te O6
<https://www.researchgate.net/publication/244748863_Sr3TeO6_and_Ba3TeO6_Double_perovskites_with_pronounced_superstructures>"
*and *"Sr Te O4
<http://scripts.iucr.org/cgi-bin/getarticleid?issn=0108-2701=41=1558=yes>".
*I understand that unit cells and space groups have been assigned, but that
is not sufficient.

If I am wrong, and ordered structures with this stoichiometry have indeed
been determined, I hope people who have access to the databases will
confirm that these structures actually exist, to save Rachid time and
money. Otherwise it is not permitted to share or promote commercial
databases on the Rietveld list.

Alan.

On 14 June 2016 at 16:42, Miguel Delgado <migu...@ula.ve> wrote:

> Dear All,
>
> For more information about the PDF-4+, feel free to visit the following
> page: http://www.icdd.com/products/pdf4.htm
>
> Kind Regards,
>
> Miguel Delgado
>
> On 6/14/2016 4:16 AM, Matteo Leoni wrote:
>
> dear everybody,
>
> I think there is some misconception here.
>
> It is true that the PDF-4+ is a commercial database: this means that
> sharing the information taken from the database (as recently done here) is
> an explicit violation of copyrights of ICDD and the violator might be
> legally prosecuted. When you use the database you save the time needed to
> look through the literature for the same information, paying the rights to
> the original owner and checking for errors in transcription and, sometimes,
> interpretation. That's why (at least) you pay for it.
>
> However, please update your records. The PDF-4+ is not the PDF-2. The
> PDF-4+ is a materials database that contains the "old" PDF-2 information,
> but it contains also structural data for a large quantity of compounds as
> well as properties and experimental patterns for several compounds. It
> contains also most of the ICSD coordinates that have been however
> thoroughly checked in house, quality marked, cross referenced and corrected
> when needed.
>
> So if the material is inorganic and the structure is not in PDF-4+, it
> usually means the structure is either very doubtful, too new or not yet
> extracted from the literature.
> In this particular case, as the chemistry and the space group are known,
> it is also likely that the compounds are isostructural to others already
> described in the literature
>
> Just notice that there are free alternatives to the commercial databases
> (e.g. COD, RRUFF) that in some cases can provide useful information, but in
> all cases the copyright warning exists
>
> Matteo (Chair of the BoD of the ICDD)
>
>
> -
>
>   Prof. Matteo Leoni, PhD
>
>   DICAM - University of Trento
>   via Mesiano, 77
>   38123 Trento - Italy
>
>   Tel +39 0461 282416 Fax +39 0461 282672
>
>   e-mail: matteo.le...@unitn.it
>
> 
>
> 2016-06-14 9:04 GMT+02:00 Alan Hewat <alan.he...@neutronoptics.com>:
>
>> maybe they are in PDF4.
>>>
>>
>> PDF4 is a commercial database of d-spacings and unit cells derived from
>> them. It does not normally contain atomic positions, and not all structures
>> in PDF4 have been determined. ICSD does contain atomic positions if they
>> have been determined.
>>
>> Both PDF4 and ICSD are copyright and must not be posted to this mailing
>> list. As well, there is an explicit warning not to attach files to the
>> mailing list. Anyone who does so risks exclusion.
>>
>> There are other free databases that may contain the information you
>> require, but I doubt it. Try using Google Scholar to first determine if the
>> structures have been published. If not, you will have to determine them
>> yourself. It is not so difficult if you have good data and know the space
>> group and lattice dimensions.
>>
>> Alan
>> __
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>> <alan.he...@neutronoptics.com> <alan.he...@neutronoptics.com>
>> +33.476.98.41.68
>> http://www.NeutronOptics.com/hewat
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>>
>> ++
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Re: atomic position

2016-06-14 Thread Alan Hewat
On 14 June 2016 at 10:16, Matteo Leoni <matteo.le...@unitn.it> wrote:

> However, please update your records. The PDF-4+ is not the PDF-2. The
> PDF-4+ ... contains also most of the ICSD coordinates that have been
> however thoroughly checked in house, quality marked, cross referenced and
> corrected when needed.


Thank you for the correction :-) As I wrote, both databases are copyright,
and since the ICSD is more complete (and probably less expensive) my advice
to purchase that is still valid, though you can already find publications
with Google. ICSD entries have also been "thoroughly checked in house,
quality marked, cross referenced and corrected when needed."
______
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Re: atomic position

2016-06-14 Thread Alan Hewat
>
> maybe they are in PDF4.
>

PDF4 is a commercial database of d-spacings and unit cells derived from
them. It does not normally contain atomic positions, and not all structures
in PDF4 have been determined. ICSD does contain atomic positions if they
have been determined.

Both PDF4 and ICSD are copyright and must not be posted to this mailing
list. As well, there is an explicit warning not to attach files to the
mailing list. Anyone who does so risks exclusion.

There are other free databases that may contain the information you
require, but I doubt it. Try using Google Scholar to first determine if the
structures have been published. If not, you will have to determine them
yourself. It is not so difficult if you have good data and know the space
group and lattice dimensions.

Alan
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Re: Help

2016-06-11 Thread Alan Hewat
On 10 June 2016 at 20:18, Rachid Abkar <rachid.ab...@gmail.com> wrote:

> I need please the space group, lattice parameter and atomic position for
> both Sr2TeO4 and Ba2TeO5


I don't know about those stoichiometries :-) but these papers might get you
started:

*"Sr Te O6 and Ba Te O6: Double perovskites with pronounced
superstructures."*
Stoeger, B.;Weil, M.;Zobetz, E. (2010)  Zeitschrift fuer Kristallographie
225, 125-138
<https://www.researchgate.net/publication/244748863_Sr3TeO6_and_Ba3TeO6_Double_perovskites_with_pronounced_superstructures>
*"Structure de Sr Te O4 sur monocristal. Organisation de structures
comportant des empilements de chaines (Te O4)n. Dimorphisme de Na2TeO4"*
Lapasset, J.;Moret, J. (1985) Acta Crystallographica C41, 1558-1562
<http://scripts.iucr.org/cgi-bin/getarticleid?issn=0108-2701=41=1558=yes>
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Re: Noise in XRD

2016-04-25 Thread Alan Hewat
You are referring to the different sources of electronic noise
<https://en.wikipedia.org/wiki/Noise_(electronics)> produced by your
detector. Frequency analysis of that noise (white noise vs noise at
particular frequencies) might tell you something about your detector, but
not about your sample. Here I assume you are talking about counting noise,
not background due to imperfect crystallinity or sample environment.

Hopefully most noise in a diffraction pattern will simply be the
statistical noise in counting individual photons or neutrons. With low
counts that will indeed have different distributions; in the background,
with asymmetric Poisson statistics with a cut-off at zero counts, and in
strong peaks, with a transition to a symmetrical normal distribution.
Fitting (smoothing), and especially Rietveld fitting which constrains the
positions and relative intensities of the peaks, will obtain the best
estimate of even weak peaks, provided you have a physically realistic model
for the scattering and not too much correlation between parameters.

For low (neutron) counts, Rietveld assigned weights inversely proportional
to the count, which can be justified by statistics, and which helps prevent
the important information in weak or absent peaks being swamped by the fit
to strong peaks. There have been attempts to shorten scanning time by
spending more time on weak peaks, which are "noisier", but in practice that
is difficult, if as usual you have a multi-detector that collects the whole
pattern at the same time. But weak or absent peaks are indeed more
important than strong peaks.

I am not sure that I have answered your questions, or even if I have
correctly understood them :-) But then you didn't receive many other
answers either.

Alan.

On 24 April 2016 at 19:16, Shay Tirosh <stiro...@gmail.com> wrote:

> Dear Rietvelders
>
> Does the noise in XRD   tell something?
>
> Correct me if I'm wrong but I think the noise on a peak is different then
> the noise in baseline.
> If this is correct then is there a possibility to identify broad peaks  or
> very small peaks? using some noise analysis.
> Can noise analysis help in better smoothing or fitting?
> Distinguishing between different noise types at baseline vs peak (Shot
> noise, flicker noise <https://en.wikipedia.org/wiki/Flicker_noise> and 
> Johnson–Nyquist
> noise <https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise>
> ) may leads to shortening the scanning time, or even to help finding the
> appropriate fitting function.
>
> Please comment
>
> Shay
>
> --
> _
>
> Dr. Shay Tirosh
> Institute for Nanotechnology & Advanced Materials
> Bar Ilan University
> Ramat Gan, 52900
> Israel
> Phone: +972-(0)30-531-7320
> Mobile: +972-(0)54-8834533
> Email: stiro...@gmail.com
> _
>
> ++
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> text
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> ++
>
>
>


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Fwd: 30th Meeting of the European Crystallographic Association, 28.8. - 1.9.2016, Basel, Switzerland: Call for early bird registration

2016-03-11 Thread Alan Hewat
30th Meeting of the European Crystallographic Association, 28.8. -
1.9.2016, Basel, Switzerland
http://ecm30.ecanews.org/ecm2016/home.html

Dear Fellow Crystallographers, dear Biologists, dear Chemists, dear
Physicists, dear Material Scientists, dear Mineralogists and other fellow
Scientists,

A very exciting European Crystallography Meeting, the ECM-30, in Basel is
now open for registration and abstract submission. Profit now from the
early registration fees at
http://ecm30.ecanews.org/ecm2016/organise-yourattendance/registration.html,
deadline on Wednesday, 20 April 2016!  A SwissFEL visit at PSI will be
organized after the conference.

Please check out our very interdisciplinary programme: you will find for
sure also some microsymposia which deal with your personal research
interests. The two Nobel Prize winners Prof. Dr. Jean-Marie Lehn and Prof.
Dr. Ada Yonath will present the plenary talks, and we could win top-level
scientists for the keynote lectures. The program of the microsymposia will
be put together based on your abstract submissions! Please submit your
abstract by 6 April 2016 to:
http://ecm30.ecanews.org/abstracts/abstract-submission.html

As a (PhD) student, you can also apply for travel bursaries (deadline is on
16 March 2016).

Basel, headquarter of major pharmaceutical and chemical industry - in the
heart of Europe - is easily reached by plane, train and car (and even by
ship)!
Basel in Switzerland, St. Louis in France and Loerrach as well as Weil am
Rhein in Germany offer many accommodations at moderate prices to lodge you
during the conference.

Hoping to see you in Basel in August this year!

Sincerely, in the name of the National Organizing Committee,
Katharina M. Fromm and Juerg Schefer
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Re: Automated XRD Date

2016-01-31 Thread Alan Hewat
   - See eg: http://www.afc.asso.fr/images/AICr2014/historique/shule.png  (C.
   G. Shull, Nobel Lecture, December 8, 1994)
   - "The diffraction of neutrons by crystalline powders", E. O. Wollan and
   C. G. Shull, Physical Review 1947, 73, 830-841
   - "Neutron Diffraction Studies of NaH and NaD", C. G. Shull, E. O.
   Wollan, G. A. Morton and W. L. Davidson, Physical Review 1948, 73, 842-847

Alan

On 31 January 2016 at 21:30, Alan Hewat <alan.he...@neutronoptics.com>
wrote:

> By automated I mean simply producing digital data, in x y pairs
>
>
> I assumed you meant automated stepping. If you mean just digital data,
> then its Shull and Wollan in the late 1940's. Neutrons were always digital
> of course; we had film and cameras much later than for x-rays.
>
> You must be younger than I thought Jim, with your 1980 memories, or else I
> am older than I think :-)
>
> Alan.
> --
> __
> *   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
> <alan.he...@neutronoptics.com> +33.476.98.41.68
> http://www.NeutronOptics.com/hewat
> ______
>



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Re: Automated XRD Date

2016-01-31 Thread Alan Hewat
Neutron diffractometers were automatic well before x-ray diffractometers,
and were also first for position sensitive detectors (PSDs) and of course
Rietveld refinement. Paper tape control was introduced in the 1950's,
computers in the early 1960's and PSD's in the early 1970's. X-rays
followed after about 10 years. From memory only. It can't be difficult to
Google this.

Alan
On 31 January 2016 at 16:47, Cline, James Dr. <james.cl...@nist.gov> wrote:

> Anyone know when/where the first automated powder diffractometer was
> commissioned?  I’m going to presume it was used with a non-laboratory source

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Re: Automated XRD Date

2016-01-31 Thread Alan Hewat
>
> By automated I mean simply producing digital data, in x y pairs


I assumed you meant automated stepping. If you mean just digital data, then
its Shull and Wollan in the late 1940's. Neutrons were always digital of
course; we had film and cameras much later than for x-rays.

You must be younger than I thought Jim, with your 1980 memories, or else I
am older than I think :-)

Alan.
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Re: Automated XRD Date

2016-01-31 Thread Alan Hewat
>
> I didn’t realize there were so many sub-developments...
>

Still, modern x-ray powder diffraction is the most important
sub-development...

Alan
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Re: structure solution terminology

2015-12-17 Thread Alan Hewat
>
> Brute force is a nicer way of putting it than blind luck :-)


Does "Tour de force" work in American ?

I have had that get by US reviewers, though they otherwise correct my
English :-)

Alan.
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Re: Selective peak broadening - interpretation and handling in FullProf

2015-08-04 Thread Alan Hewat
On 4 August 2015 at 11:54, Kotaro SAITO kotaro.sa...@kek.jp wrote:

 Or do I miss some basic points about diffraction?


I won't try to address your specific material... and I'm being called to
lunch :-) But for beginners who may be lost in these technical papers, I
will attempt the following trivial explanation

If you have a layered material where two layers A and B are slightly
different you will have super-structure reflections. These will be as sharp
as the main reflections (from the average structure) if the order of the
layers is perfectly regular ABABABAB...

But if the layers only have short-range order eg ABABBABAAB... then these
superlattice reflections will be broadened, and even completely washed out
if the order between layers is completely random. Otherwise the width
delta-d of the superstructure reflections will give you the short range
order length - the shorter the correlation length the broader the
superlattice reflections.

Obviously delta-d doesn't depend on the d-spacing between layers, only on
the length of their order. So the broadening is constant in d-space as
usually plotted for TOF neutron diffraction.

For angular dispersion eg with a constant x-ray or neutron wavelength,
Bragg's law 2d.sin(theta)=lambda comes in. If you differentiate Bragg's law
you will find a simple relation between delta-d and delta-2theta, the line
broadening for angular dispersion measurements.

Alan.
(Everything should be as simple as possible... but no simpler.)
BTW, thanks for using dropbox instead of an attachment. That's the way to
go...
-- 
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Re: Proposal to avoid banning for attachments in the list

2015-07-15 Thread Alan Hewat
Dear Fabrizio.

1) I would be happy if you or other members created such a dropbox to allow
people to post images, linking to them in their Rietveld posts. The main
problem with images is simply that they are not archived on
http://www.mail-archive.com/rietveld_l@ill.fr/ so are not available for
future reference.

2) But apparently not everyone thinks their images need be archived - you
yourself propose they be deleted after one month. In that case, I propose
that since we already made an exception for Jim, as a test, we allow such
people to post small images (75 kbyte) directly to the Rietveld mailing
list.

They will not be archived, and I personally think that reduces the interest
of the archive, but I concede that other people have a different opinion.
Vive la difference !

Alan

On 15 July 2015 at 08:12, Fabrizio Guzzetta fabrizio.guzze...@gmail.com
wrote:

 I have seen, in the past, that the argument of attachments in the
 mails/reply is always under debate and I understand both parties, the one
 that is pro-attachments because we are visual in the senwe that an image
 can explain better than tons of words sometimes or for particularly
 difficult patterns to visualize, particular problems which can't be
 resolved with proper data posting and so on, and the other one which has
 designed the mailing list this way, probably to avoid scams/viruses/etc...

 So I want to make my proposal: why don't we create a virtual space in the
 clouds (e.g. dropbox), shared between the Rietvelders/crystallographers
 where the attachments will be put according to specific arguments (and
 date), and moderated in turn by few rietvelders (who can and want to do
 this, nothing is imposed) to erase data every month (or so) old data
 previous an email remainding when old data will be deleted? This will also
 eliminate or  reduce the needs for hyperlinks.

 I hope not to be crucified and especial y I ask Alan (who created this
 list) an opinion on that.

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Re: Obtaining a silicon standard wafer

2015-07-14 Thread Alan Hewat

 I have always found more useful having LaB6 or corundum


Fabrizio's question why use silicon powder might have been answered more
precisely, and in much less than 64 ko (~64,000 letters :-) as follows:

The line width of the NIST Si powder sample 640e is no better than the NIST
sintered corundum disk 1976b, which is also slightly cheaper at $680. The
best NIST x-ray standard is however LaB6 powder 660c, which is 50% more
expensive; the line widths of the other two are 50% greater.

The recipe for making a silicon disk from powder is interesting, but why
bother if you can buy the sintered Al2O3 disk, if indeed you want a disk
rather than powder.

Alan
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Re: Obtaining a silicon standard wafer

2015-07-14 Thread Alan Hewat
Thanks for pointing that out David. I should have checked that my reply did
not also include Jim's illustration, which was actually not an attachment
but part of an HTML email. I guess that is why it was not filtered out.

It is rather amusing and a good joke on me. As penance I will re-instate
Jim, but I still think he should put such useful illustrations on his NIST
product page and just link to them. As it is, the essential information is
lost to the Rietveld archive, which doesn't reproduce anything more than
text.

Regards, Alan.

On 14 July 2015 at 16:40, David Elbert elb...@jhu.edu wrote:

 Hi Alan-

 Just a quick suggestion.  You might want to check your mail client
 behavior.  Your reply telling Jim he is banned for sending an attachment
 contained the same attachment.

 I believe many clients default to include attachments when mails are
 forwarded or redirected, but strip the attachment when a user chooses
 reply.”  Perhaps your email system doesn’t do that or needs to be
 configured to do that?

 (I’m sure several Rietveld List users will find the humor in this and
 wonder if you are now banned, but I think things got touchy enough a few
 weeks ago and so hope we can avoid too much back-and-forth about that.
 After all, it can be very hard in an email to tell the subtleties of when
 someone is joking, poking fun, being puckish, reproachful, chiding,
 scolding, rebuking… and all with differences depending on language and
 culture.)

 Regards-
 David

 David Elbert
 Earth and Planetary Sciences
 Olin Hall
 Johns Hopkins University
 3400 N. Charles St
 Baltimore, MD 21218

 (410) 516-5049

 elb...@jhu.edu








 On Jul 14, 2015, at 7:18 AM, Alan Hewat alan.he...@neutronoptics.com
 wrote:

 Sorry Jim. Even if your attachment is tiny, if I make exceptions it's
 unfair to those who have been banned for the same thing. It's only a week,
 and nothing personal.

 Why don't you put these plots on your sales site:
 https://www-s.nist.gov/srmors/viewTableH.cfm?tableid=149

 Alan.

 On 14 July 2015 at 12:53, Cline, James Dr. james.cl...@nist.gov wrote:

  I hope I don’t get shot for this, only 64 kb:



 FWHM values of various SRMs:

 Regards,



 Jim





 James P. Cline
 Materials Measurement Science Division
 National Institute of Standards and Technology
 100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
 Gaithersburg, MD 20899-8523USA
 jcl...@nist.gov
 (301) 975 5793
 FAX (301) 975 5334



 *From:* Fabrizio Guzzetta [mailto:fabrizio.guzze...@gmail.com]
 *Sent:* Tuesday, July 14, 2015 3:24 AM
 *To:* Cline, James Dr.
 *Cc:* Young, Lindsay Kay; rietveld_l@ill.fr
 *Subject:* Re: Obtaining a silicon standard wafer



 Thanks Jim for the useful info. I was not aware of this kind of silicon
 standard until now. But can't be polycrystallinity of Silicon a drawback to
 use it as standard? Or is there a way to purify a single phase suitable
 to use as standard? I have always found more useful having LaB6 or corundum
 (whenever LaB6 is expensive to find) to use it as standard to compare
 instrumental peak broadening. In some of the Rietveld software I use or I
 know, also yttria is used to determine peak broadening. Which criteria do
 you use when choosing a suitable pxrd standard to compare your unknown? Why?



 Thanks for the enlightening discussion.


Fabrizio Guzzetta

 Ph.D. student, Dept. Quimica Inorganica y Organica, UJI

 Castellon de la Plana

 Spain



 2015-07-13 19:56 GMT+02:00 Cline, James Dr. james.cl...@nist.gov:

 Lindsay,



 I’ve seen pressed discs of silicon powder that were supplied with older
 Philips diffractometers, and I understand that PANalytical will presently
 supply them with their new machines.  NIST offers no such standard of
 silicon in a disc format.  But I can suggest that you consider SRM 640e
 which is supplied as powder.  One can mount a specimen of it carefully to
 obtain high density and a flat specimen surface, and then infiltrate the
 powder bed with silicone based liquid resin such as Vacseal.  See:



 http://www.2spi.com/catalog/vac/vacleak.shtml



 The surface of the compact will darken to a uniform color when the
 infiltration is complete.  This will result in a stable compact with the
 diffraction properties of SRM 640e.



 Regards,



 Jim





 James P. Cline
 Materials Measurement Science Division
 National Institute of Standards and Technology
 100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
 Gaithersburg, MD 20899-8523USA
 jcl...@nist.gov
 (301) 975 5793
 FAX (301) 975 5334



 *From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] *On
 Behalf Of *Young, Lindsay Kay
 *Sent:* Friday, July 10, 2015 1:28 PM
 *To:* rietveld_l@ill.fr
 *Subject:* Obtaining a silicon standard wafer



 Hello Rietvelders -



 This is not exactly a data question, but I am sure someone here can help.
 I am looking into purchasing a silicon powder standard wafer for PXRD
 instrument alignment. However, I am not sure where to get one or how much I
 might expect one

Re: Obtaining a silicon standard wafer

2015-07-14 Thread Alan Hewat

 if you would like a preprint, send me an email.


Yes, that's the way people should offer supplementary material to list
users. Or even better, link to your preprint.


 Why don't you put these plots on your sales site...

The SRM people would never do this as they would have to explain the plot
 in a technical manner to inquiring customers.


Well, the documents on the NIST site are already quite technical, and
contain plots, just not the nice comparative plots  you might need when
choosing a line standard eg
https://www-s.nist.gov/srmors/certificates/view_certGIF.cfm?certificate=640E

 What year is it ? I find it silly to discuss inclusion of a 64K image in
email

OK Frank, but until someone sets up an email archive that reproduces
images, they are lost to others if they are simply included in an email -
see https://www.mail-archive.com/faq.html#attachments and the bit about
performance.

Frankly, I am indeed a little old-fashioned. If you can't find it with
Google... it doesn't exist.

Alan.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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++



Re: What's in a name?

2015-07-03 Thread Alan Hewat
No problem with people asking not strictly Rietveld questions Tim.
But the list is named in honour of Hugo Rietveld, and that seems right to
me.
Besides, it's shorter than either of your suggested titles :-)
Alan.

On 3 July 2015 at 18:35, Timothy Hyde timothy.h...@matthey.com wrote:

  “Dear All,

 Sorry not a direct Rietveld question, but I hope somebody can help……….”



 Alan,



 Second such question of the day! Perhaps (not wanting to go too much over
 old ground re Facebook/social media etc) all that is required to grow
 membership/usage is a simple name change of the group? I suggest “Sorry not
 a direct Rietveld question, but I hope somebody can help…”



 Perhaps  “XRD and Rietveld” would be less cumbersome and inform potential
 new members that Rietveld is only a fraction of the discussion topics on
 the list? Any thoughts?



 Tim Hyde





 *From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] *On
 Behalf Of *Natale Perchiazzi
 *Sent:* 03 July 2015 16:10
 *Cc:* rietveld_l@ill.fr
 *Subject:* D2 phaser info








Dear All,

 Sorry not a direct Rietveld question, but I hope somebody can help. We are
 evaluating to get a D2 Phaser diffractometer. If somebody has got this
 equipment and wish to share his experience with the machine, infos are
 warmly welcome .

 Best regards Natale Perchiazzi

   __



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++



Re: Cyberstar hot air blowers

2015-07-03 Thread Alan Hewat
2000 CHF? Precise temperature control is essential since often you will
want to work near transitions where you risk destroying your sample. That
also costs.

_
  From my mobile telephone
 Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
alan.he...@neutronoptics.com +33.476.98.41.68
  http://www.NeutronOptics.com/hewat
_
On 3 Jul 2015 11:38, Yaroslav Filinchuk UCL 
yaroslav.filinc...@uclouvain.be wrote:

  Hello Simon,

 we are successfully using a programmable hot air blower (25-750°C) called
 Le Mini Sensor Kit 800, from the Swiss company Leister. It costs about 2000
 CHF, and is aimed at the industrial use. It allows to do ramps, it follows
 the protocol very closely, but the temperatures and real ramp rates have to
 be calibrated.

 Best regards,
 Yaroslav



 Friday, July 3, 2015, 10:38:50 AM, you wrote:



   Dear All,

 Sorry not a direct Rietveld question, but I hope somebody can help  : )

 We often use high temperature (RT - 1000 C) gas blowers at ESRF for their
 flexibility and low background. Those made by Cyberstar seem to have become
 prohibitively expensive. Does anyone know of a competing supplier?

 best wishes,

 Simon

 --
 -
 Dr. Simon A.J. Kimber
 European Synchrotron Radiation Facility,
 71 Avenue des Martyrs,
 38000 Grenoble,
 France.
 0033 (0)47688 2773



 ++
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 text
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 ++



++
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++



RE: Cyberstar hot air blowers

2015-07-03 Thread Alan Hewat
I was not complaining about the cost, just questioning what was quoted -
only two thousand CHF ? Does that include a precise temperature controller
- or just the hot air ?

_
  From my mobile telephone
 Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
alan.he...@neutronoptics.com +33.476.98.41.68
  http://www.NeutronOptics.com/hewat
_
On 3 Jul 2015 12:52, Radovan Cerny radovan.ce...@unige.ch wrote:

  Complaining about the cost of small Swiss companies is not appropriate
 on the Rietveld list J



 On Facebook it would be automatically censored by BB …



 I have the same heater, and once you calibrate it is quite stable and
 precise.



 Destroying the samples is more expensive in the industry than in our labs …





 Radovan Cerny

 Laboratoire de Cristallographie, DQMP

 Université de Genève

 24, quai Ernest-Ansermet

 CH-1211 Geneva 4, Switzerland

 Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08

 mailto : radovan.ce...@unige.ch

 URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm



 *De :* alan.he...@gmail.com [mailto:alan.he...@gmail.com] *De la part de*
 Alan Hewat
 *Envoyé :* vendredi 3 juillet 2015 12:15
 *À :* Yaroslav Filinchuk UCL
 *Cc :* SAJ Kimber; rietveld_l@ill.fr
 *Objet :* Re: Cyberstar hot air blowers



 2000 CHF? Precise temperature control is essential since often you will
 want to work near transitions where you risk destroying your sample. That
 also costs.

 _
   From my mobile telephone
  Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
 alan.he...@neutronoptics.com +33.476.98.41.68
   http://www.NeutronOptics.com/hewat
 _

 On 3 Jul 2015 11:38, Yaroslav Filinchuk UCL 
 yaroslav.filinc...@uclouvain.be wrote:

 Hello Simon,

 we are successfully using a programmable hot air blower (25-750°C) called
 Le Mini Sensor Kit 800, from the Swiss company Leister. It costs about 2000
 CHF, and is aimed at the industrial use. It allows to do ramps, it follows
 the protocol very closely, but the temperatures and real ramp rates have to
 be calibrated.

 Best regards,
 Yaroslav



 Friday, July 3, 2015, 10:38:50 AM, you wrote:

 Dear All,

 Sorry not a direct Rietveld question, but I hope somebody can help  : )

 We often use high temperature (RT - 1000 C) gas blowers at ESRF for their
 flexibility and low background. Those made by Cyberstar seem to have become
 prohibitively expensive. Does anyone know of a competing supplier?

 best wishes,

 Simon

 --
 -
 Dr. Simon A.J. Kimber
 European Synchrotron Radiation Facility,
 71 Avenue des Martyrs,
 38000 Grenoble,
 France.
 0033 (0)47688 2773


 ++
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 text
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 http://www.mail-archive.com/rietveld_l@ill.fr/
 ++


++
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++



Re: TOPAS Macro Language (peak shape broadening macros)

2015-06-24 Thread Alan Hewat
Both Peter and Luca are correct :-) Preferred orientation can indeed be
used to help SOLVE (unknown) structures, but when you want to REFINE
structures you should try to eliminate systematic errors such as preferred
orientation, if possible by better sample preparation. That may not be
possible with highly oriented crystallites such as nanotubes, and as Naveed
found, modelling peak broadening will not help. Search the program manual
for texture or preferred orientation modelling.
Pax. Alan.

On 24 June 2015 at 17:44, Khalifah, Peter kp...@bnl.gov wrote:

  Yes, that is of course a more precise and correct answer.  I did not
 mean to imply that diffraction physics work differently, just that the data
 processing resulted in some badly wrong assumptions about the data being
 used for Rietveld refinement.



 I tried to give a quick answer to a basic question from a basic point of
 view.  If it was an expert question, I would have left it to the experts
 like you :-)



 -Peter



 *From:* Luca Lutterotti [mailto:luca.luttero...@ing.unitn.it]
 *Sent:* Wednesday, June 24, 2015 3:52 AM
 *To:* Khalifah, Peter
 *Cc:* rietveld_l@ill.fr
 *Subject:* Re: TOPAS Macro Language (peak shape broadening macros)





  On 23 Jun 2015, at 22:22, Khalifah, Peter kp...@bnl.gov wrote:



 Preferred orientation results in the central assumption that the measured
 intensity is proportional to the reflection structure being violated,



 This is actually quite new to me as definition of preferred orientation or
 better texture. Until now I thought that in the case of preferred
 orientations the measured intensity is proportional to the volume fraction
 of grains oriented in a certain direction…….



  As many people will tell you, it is much more effective to eliminate
 preferred orientation (though improved sample preparation) than to try to
 model it.



 We actually use preferred orientation (texture) to help structure
 solution, and I found more easy to model them than to eliminate them. But
 may be is just me.



 Best regards,



 Luca Lutterotti



 ---Luca
 Lutterotti

 Dipartimento di Ingegneria Industriale, Universita' di Trento,

 via Sommarive 9, 38123 Trento, Italy

 Temporary address:

 Laboratoire CRISMAT-ENSICAEN, Université de Caen Basse-Normandie, Campus 2

 6, Bd. M. Juin 14050 Caen, France

 e-mail address : luca.luttero...@unitn.it
 Home page : http://www5.unitn.it/People/en/Web/Persona/PER0004735
 New Maud page : http://maud.radiographema.com

 Phone number :+39-0461-28-2414
 Fax :
 +39-0461-28-1977--

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 ++





-- 
__
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Re: Powder Diffraction Discussion Group on Facebook

2015-06-12 Thread Alan Hewat
After all this discussion, the post on Anomalous Scattering illustrates
both the interest and the limitations of the Rietveld mailing list.

1. It shows that a good question will rapidly receive answers from experts
in the field.
2. Both question and answers will be read by a large number of others,
because they receive a personal email, wherever they are in the world, even
without high speed internet.
3. And the discussion is archived on a public WWW server that is open to
everyone, not just list members. This is important in that Google indexes
it, so people will find it long after.

It also illustrates the disadvantages of which others have complained :-)

1. This discussion would have profited if illustrations were allowed.
However, one answer linked to a more complete discussion that included
illustrations. That is the way I think it should work.
2. The answers were perhaps a little too technical for the inexperienced
student. Experts should be able to express complex ideas in ways that at
least show beginners where to start. But that is not the fault of the list
format.

I encourage those who think they have a better solution to go for it, but
also warn them that others have tried :-) Jon mentioned the SPDP list as a
good example. The SPDP list is also an archived email list, though the
archive is members only. Armel, who is still a member of the Rietveld list.
also tried other solutions, and concluded a web-based SDPD forum was first
opened, which had a limited success probably because there was no email
distribution: subscribers had to go to the web pages and see if there was a
new discussion.

Those who object to email simply because it's been around a long time, may
equally well object to me :-) But I receive my emails instantly on my
Android 5.0 phone, wherever I am, just like SMS, Tweets or whatever. So, if
it helps, just think of email as a kind of bigger tweet.

Re-invent the wheel - and name it something else. Alan.

Sent from my phone.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
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++



Re: Experimental and calculated RIRs of metals from ICDD

2015-06-11 Thread Alan Hewat
Hi Leonid.

I can't answer your question, but want to warn you that Gmail put your
email into my spam folder with the following explanation: Why is this
message in Spam? It has a from address in yahoo.com but has failed yahoo.com's
required tests for authentication.

I don't understand Gmail's tests, and this problem is not due to the
Rietveld server. Your message was distributed and is already in the archive
http://www.mail-archive.com/rietveld_l@ill.fr/ but Gmail users (there are a
lot) may miss your message unless they manually check their spam folder.

For all Rietveld list members - if your message to the list is rejected, it
will be because the email address you are using is not identical to that
with which you subscribed. If your address changes, you must subscribe
again to be able to post, even though you may still RECEIVE messages via
forwarding. This list is not moderated. Whether your message is posted or
not is entirely decided by the SYMPA server software.

Alan.

On 11 June 2015 at 08:07, Leonid Solovyov l_solov...@yahoo.com wrote:

 Dear Rietveldians,

 Can anybody give an explanation of a severe discrepancy in the
 experimentally measured Reference Intensity Ratios (RIR) and those
 calculated from structure for some metals, such as Zn, Ti, Cd etc. in the
 ICDD PDF?
 In particular for Zn, the experimental RIR from ICDD PDF 00-004-0831 is
 3.8, while the calculated RIR from PDF 01-078-9363 is 8.39. For Cd the
 difference is more impressive: RIR=2 in PDF 00-005-0674 and 15 in PDF
 01-071-3769.
 For the experimental RIRs a reference is given: Swanson, Tatge., Natl.
 Bur. Stand. (U. S.), Circ. 539, I, 16, (1953), which is inaccessible for
 me, unfortunately.

 Any hypothesis?
 Leonid

  ***
 Leonid A. Solovyov
 Institute of Chemistry and Chemical Technology
 660036, Akademgorodok 50/24, Krasnoyarsk, Russia
 http://sites.google.com/site/solovyovleonid
 ***

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 ++





-- 
__
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Re: Powder Diffraction Discussion Group on Facebook

2015-06-09 Thread Alan Hewat

 the Rietveld mailing list is still where the best knowledgeable is


That's encouraging Alan. Thanks. Concerning the number of posts you are
right - there are fewer now. I would like to think it's because we have an
archive now, and people profit from past answers rather than asking the
same questions over again, which used to be common. Or perhaps its because
there are now more channels of information.

While the number of posts has diminished, the number of members has grown
continually. There are now more than 1500, but some well known names only
post when they see a particularly interesting question. Whenever there is a
good question, we receive good answers.

As for insults, I thought Radovan's cleavage between Troglodytes and
Tweeters was quite amusing. And every time we have a little controversy,
we get new members.

One shouldn't assume that because fewer people post, there are fewer people
interested. But certainly prepare a graph if you wish. Just don't post it
to all 1500+ members :-)

Kind regards, Alan.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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++



Re: Powder Diffraction Discussion Group on Facebook

2015-06-08 Thread Alan Hewat
I can understand that people have different ideas about the ideal format
for discussion, and for some of us email may seem a little old fashioned.
I suppose we could also use Twitter or any of the other social chattering
forums. But multiple groups on the same subject disperses the available
information, and it would be good to have some kind of consensus rather
than individual initiatives.

The advantage of the Rietveld mailing list is that contributions aren't
anonymous, it is not commercial and no use is made of users' information,
publicity is limited, and there is a structured archive of discussion that
is open to all, even those who don't have an account.

I myself simply inherited the list, but think it worth maintaining, and
would discourage members from posting to multiple groups on the same
subject.

Alan. (What, me worry ? :-)

On 8 June 2015 at 09:24, davide levy davide.lev...@gmail.com wrote:

 Good Morning
 I created the Powder Diffraction Discussion Group on Facebook, to speak
 about powder diffraction, Rietveld etc..  open for all use powder
 diffraction.
 https://www.facebook.com/groups/1087352967946225/
 Davide

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-- 
__
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Fwd: Neutron Scattering Applications to Hydrogen Storage Materials

2015-05-12 Thread Alan Hewat
*+++We kindly invite you to the upcoming Neutron School 2015+++*



*Neutron Scattering Applications to Hydrogen Storage Materials*

*17th-26th of August 2015 at Helmholtz-Zentrum Berlin*

*Hahn-Meitner Platz 1, 14109 Berlin, Germany*



*SCOPE*

Energy research is an important scientific area today and hydrogen is one
of the most promising sources of energy due to its highest energy density
by weight. The efficient hydrogen storage depends on development of the new
materials. Neutron scattering and -diffraction are powerful,
non-destructive tool for the analysis of structure and dynamics in matter
in a broad space and time domain. High sensitivity to hydrogen makes
neutron scattering techniques ideally suitable to study the process in
hydrogen storage systems. The goal of this school is to introduce
participants to basics of neutron scattering techniques and show how these
techniques can be applied for exploration of hydrogen storage materials.



The school is organized jointly by University of Potsdam, Germany and
University of Tartu, Estonia. It will be held from 17th – 26th of August
2014 at the Helmholtz-Zentrum Berlin (HZB), Berlin, Germany.

The lectures and practical exercises will give basics to:



-   *Hydrogen economy and hydrogen storage technologies*

-   *Fundamentals of the gas storage  *

-   *Basics of the neutron scattering and in particular in-situ neutron
diffraction *

-   *Characterizing sorption behavior of porous materials by ab-initio
and crystal structure refinements*



Lectures: M. Russina (HZB), H. Kurig (University of Tartu, Estonia), D.
Többens (HZB), D. Wallacher (HZB), M.C. Schlegel  and Roman Svetogorov
(NRC, Mocsow)



*Target group*

The course is primarily aimed at early stage researchers with basics
knowledge in Thermodynamics

and Solid State Physics. It is part of the curriculum of the Faculty of
Mathematics and Sciences at the University of Potsdam, Modul 741A and is
credited with 4 credit points.



*Registration *

If you are interested in attending the school, please follow this link:

*www.helmholtz-berlin.de/events/hydrogen-school
http://www.helmholtz-berlin.de/events/hydrogen-school *





*Please register until May, 25th 2015*



Kind regards



Dr. Moritz-Caspar Schlegel

BAM Federal Institute for Materials Research and Testing

BAM-S.4 Ecodesign

Unter den Eichen 87

12205 Berlin / Germany

Phone: +49 (0)30 -8104-3808

Fax: +49 (0)30 -8104-1947

E-mail: *moritz-caspar.schle...@bam.de moritz-caspar.schle...@bam.de*


--

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren
e.V.

Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv.
Vorsitzende Dr. Beatrix Vierkorn-Rudolph
Geschäftsführung: Prof. Dr. Anke Rita Kaysser-Pyzalla, Thomas Frederking

Sitz Berlin, AG Charlottenburg, 89 HRB 5583

Postadresse:
Hahn-Meitner-Platz 1
D-14109 Berlin

http://www.helmholtz-berlin.de
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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++



Re: This and that

2015-05-12 Thread Alan Hewat
Hi Mike. It is great to have the Vice-President of the IUCr contributing
again to the list, so I will have to be serious:-) The problem is, the list
does sometimes become a little moribond without occasional provocation.

The current discussion touched on many interesting subjects - the poor
quality of some published data, the interpretation of multi-phase patterns,
the determination of symmetry and the interpretation of line-broadening,
serial crystallography or single-crystal data from powders, and even
non-crystal techniques such as single-molecule image reconstruction (XFEL)
and single-particle cryo-EM.

These new non-crystal techniques are indeed exciting, and related to much
older tomography techniques as Jon implied, where large numbers of 2D
projections can be reconstructed as a 3D image. A big difference is that
with classical tomography you know the relative orientations, whereas with
the xFEL and cryo-EM techniques you have to determine that for each
molecule - you don't have a crystal to help you. These techniques are far
from the expertise of most of us here, who indeed will still need crystals,
usually as powders for inorganic materials.

I too would like to see the list with more discussion of current techniques
and publications, even if some of the comments appear provocative or even
snarky. At least the members of this list have a certain expertise and sign
their name to their comments, unlike the comments at the bottom of the
Science article:
http://news.sciencemag.org/biology/2015/05/electron-microscopes-close-imaging-individual-atoms

BTW Mike, when I said that all structures are triclinic I was joking;
actually most of them are monoclinic:-)

Alan.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
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++



Re: Apologies... The No Attachment rule.

2015-05-10 Thread Alan Hewat
Dear Leo.

I want to assure you that my reaction was not specifically directed at you.
Other well known crystallographers have also been suspended for a short
time, and I must apply the same rules to everyone.

Yes, I can see that the paper is already published on the web, but I still
think that it would have been better to just include that link even though
not everyone will have access to ScienceDirect. You might also have
explained briefly that the statistics are remarkably poor, and that it is
very difficult to conclude on the basis of the appearance of a few very
weak peaks that the material includes a second phase (only) for x0.3

And yes, J.Mag.Mag.Mat. is a well respected journal that includes a lot of
crystallography, especially with neutrons. It is disappointing that such
poor data is accepted.

Alan.
PS In copying my reply to the Rietveld list, I naturally take
responsibility for revealing the link to the paper. If it is already
published on ScienceDirect, then people can publicly comment on it IMHO.

On 9 May 2015 at 15:26, Leopoldo Suescun leopo...@fq.edu.uy wrote:

 Dear Alan,
 Thanks for your clarifying opinion.

 I just want to clarify that my only violation on this issue was the
 attached figure.

 There was none related to the figure itself that is published on-line (for
 people with access -
 http://www.sciencedirect.com/science/article/pii/S0304885315300408). This
 is a web version that is ahead of the paper version by many months, that´s
 why I said that it will be published in September 2015.

 Additionally I just wanted to show an example, of many I have seen, but
 was very eye-catching. I did not wanted to make a point respect to the
 specific journal or the authors, that was the reason for not linking to the
 on-line version of the paper itself...

 Maybe wrong way of rising the point (the attachment) and wrong choice of
 words (sounding this was unpublished) but my worry and that of many are
 the point (unfortunately almost nobody referred to it) and maybe we should
 start looking for ways to prevent this kind of degradation in generally
 trustworthy journals...

 With best regards,
 Leo


 2015-05-09 6:39 GMT-03:00 Alan Hewat alan.he...@neutronoptics.com:

 Dear Rietveld list.

 Good to see so many people asking for the list to be continued. And even
 an example of an interesting scientific question immediately answered by an
 expert. Encouraging.

 So why do I forbid sinful attachments ? (No, it's not because I'm
 getting old and snarky, though we all do eventually :-) Think of the
 Rietveld list as a kind of relaxed Twitter, except that you are not
 limited to 140 characters. And what about Google's decision this month to
 favour sites that can be used on a mobile phone ? Yes, even oldies use
 mobile phones for email. SMS is another example of beauty in brevity.

 Then the Rietveld Archive is an excellent record of past discussions -
 without the attachments. Messages that rely on attachments are then often
 incomprehensible - look up that message on
 https://www.mail-archive.com/rietveld_l@ill.fr/ Frankly, if you need
 more than that, put it on a webserver with a link to it. Such links are
 preserved in the archive.

 If you see my own warning about no attachments as an attachment :-)
 perhaps you should check how your email client is set up. Or tell me how I
 can do it differently with SYMPA www.sympa.org I didn't design the mail
 server nor the mail archive. Clearly, it is difficult to enforce a simple
 no attachments rule, so what would it be like policing a small
 attachments rule ? Even if you personally have lots of space for email,
 our webserver (for which we don't pay) would still have to distribute ~1500
 copies of your small attachment.

 In this particular case, a figure from an unpublished paper was published
 and criticised out of context. Is that really fair? If it's from a
 referee's copy we shouldn't even refer to it, let alone publish it. If it's
 a pre-print, just publish a link to it. But there are already plenty of
 examples in the published literature if you are looking for evidence of
 regression.

 So where are the Apologies? There are none :-) Excuse me is what
 people say when they elbow their way through a crowd. (I only do that when
 I really need to). So if you really need to attach a document, go ahead.
 After all, you can still read the list on the archive.

 Alan

 __
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++



Re: Apologies... The No Attachment rule.

2015-05-10 Thread Alan Hewat
Dear Song Zhen.

Thank you for the detailed instructions on how to ensure that my footer is
appended to the main text rather than attached. I agree that in-line
signatures are better than those attached (Microsoft style visiting cards)
and probably I chose the plain text setting rather than mime. In the
Rietveld archive https://www.mail-archive.com/rietveld_l@ill.fr/ where only
plain text is preserved and attachments aren't, my footer is still there,
which makes me think that it is already appended in-line, but I will check
on the server next week.

Your suggestion of how to prevent attachments will also be followed up. I
probably interpreted publicnomultipart to be anyone can send messages,
while I want to restrict sending to members to prevent spam. But the
nomultipart seems to be the key to preventing attachments, so I will look
at that too.

Thank you again for your suggestions. I am not an expert with mail servers,
and the SYMPA instructions seem rather complex.

With kind regards, Alan.

On 9 May 2015 at 13:16, azurebayer azureba...@163.com wrote:

 Dear Alan,
 Maybe the below information is useful for you to solve your problems:
 1. The message-footer.txt attachment.
 Per default, your mailing list setting for a footer type is set to
 'append', which appends the footer as plain text. If you compose messages
 to your list mainly in HTML or Rich-Text format, this might not be the
 right setting for you. The message entails so-called MIME parts with
 different format versions (plain-text and HTML in that case). Most email
 clients display only the HTML version and therefore not the appended
 plain-text footer. Changing the attachment type fixes this.

 Email format / Sympa setting
 append  mime
 HTML   no visible
 footer visible footer + attachment
 Rich-Text no visible
 footer visible footer + attachment
 Plain-Textvisible
 footer  visible footer

 To fix this please follow these steps to set up the footer attachment type:
 1.Login to your Sympa account.
 2.Under Your Lists click Admin  Edit List Config  Sending/reception.
 3.In the right-hand pane, near the bottom, change the Attachment type 
 by clicking the pulldown-arrow and selecting mime.
 4.Click the Update button at the end of the page.

 2. Attachment forbidden
 Sending Scenarios
 To change which send scenario is being used for your list, select the list
 under “Your Lists,” then click “List Administration” in the “List
 Operations” section, then “Edit List Configuration,” and finally
 “Sending/Receiving Setup” — the send scenario choices are in the first
 section, named “Who can send messages.” Available choices include:
 ...
 publicnomultipart
   Anyone may send to the list. Messages with attachments are
 simply rejected.

 Good luck!
 Song Zhen


 --

 Song Zhen

 Department of Materials Physics and Chemistry

 University of Science and Technology Beijing

 At 2015-05-09 17:39:46, Alan Hewat alan.he...@neutronoptics.com wrote:

 Dear Rietveld list.

 Good to see so many people asking for the list to be continued. And even
 an example of an interesting scientific question immediately answered by an
 expert. Encouraging.

 So why do I forbid sinful attachments ? (No, it's not because I'm
 getting old and snarky, though we all do eventually :-) Think of the
 Rietveld list as a kind of relaxed Twitter, except that you are not
 limited to 140 characters. And what about Google's decision this month to
 favour sites that can be used on a mobile phone ? Yes, even oldies use
 mobile phones for email. SMS is another example of beauty in brevity.

 Then the Rietveld Archive is an excellent record of past discussions -
 without the attachments. Messages that rely on attachments are then often
 incomprehensible - look up that message on
 https://www.mail-archive.com/rietveld_l@ill.fr/ Frankly, if you need more
 than that, put it on a webserver with a link to it. Such links are
 preserved in the archive.

 If you see my own warning about no attachments as an attachment :-)
 perhaps you should check how your email client is set up. Or tell me how I
 can do it differently with SYMPA www.sympa.org I didn't design the mail
 server nor the mail archive. Clearly, it is difficult to enforce a simple
 no attachments rule, so what would it be like policing a small
 attachments rule ? Even if you personally have lots of space for email,
 our webserver (for which we don't pay) would still have to distribute ~1500
 copies of your small attachment.

 In this particular case, a figure from an unpublished paper was published
 and criticised out of context. Is that really fair? If it's from a
 referee's copy we shouldn't even refer to it, let alone publish it. If it's
 a pre-print, just publish a link to it. But there are already plenty

Re: Apologies... The No Attachment rule.

2015-05-10 Thread Alan Hewat

 maybe I should duck back down behind the parapet and continue as only an
 observer!


No, it was a good joke Darren. We need more of that. Don't be put off by
snarky comments. Jon's comment was also more of a joke than a snark. What
he is doing is more interesting so far than the gedanken experiments on
XFEL sources to which he referred.

Regards, Alan.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++



Seeking a research associate at NIST (forwarded message)

2015-05-09 Thread Alan Hewat
Forwarded for Igor Levin (NIST):

We are seeking a research associate to work at the National Institute of
Standards and Technology (Gaithersburg, MD, USA) on computational problems
in crystallography.  The desired skills include knowledge of computational
physics (e.g. numerical linear algebra, optimization techniques, Monte
Carlo methods, interpolations and approximation techniques), computer
programming (e.g. R, Python, C, C++, FORTRAN), and statistics (Bayesian
analysis, regression analysis, stochastic processes).  Some knowledge of
solid-state physics and familiarity with X-ray/neutron scattering methods
would be a plus.  The position is available immediately. For further
information contact Igor Levin, igor.le...@nist.gov.

Kind Regards,

Igor Levin
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
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++



Apologies... The No Attachment rule.

2015-05-09 Thread Alan Hewat
Dear Rietveld list.

Good to see so many people asking for the list to be continued. And even an
example of an interesting scientific question immediately answered by an
expert. Encouraging.

So why do I forbid sinful attachments ? (No, it's not because I'm getting
old and snarky, though we all do eventually :-) Think of the Rietveld list
as a kind of relaxed Twitter, except that you are not limited to 140
characters. And what about Google's decision this month to favour sites
that can be used on a mobile phone ? Yes, even oldies use mobile phones for
email. SMS is another example of beauty in brevity.

Then the Rietveld Archive is an excellent record of past discussions -
without the attachments. Messages that rely on attachments are then often
incomprehensible - look up that message on
https://www.mail-archive.com/rietveld_l@ill.fr/ Frankly, if you need more
than that, put it on a webserver with a link to it. Such links are
preserved in the archive.

If you see my own warning about no attachments as an attachment :-)
perhaps you should check how your email client is set up. Or tell me how I
can do it differently with SYMPA www.sympa.org I didn't design the mail
server nor the mail archive. Clearly, it is difficult to enforce a simple
no attachments rule, so what would it be like policing a small
attachments rule ? Even if you personally have lots of space for email,
our webserver (for which we don't pay) would still have to distribute ~1500
copies of your small attachment.

In this particular case, a figure from an unpublished paper was published
and criticised out of context. Is that really fair? If it's from a
referee's copy we shouldn't even refer to it, let alone publish it. If it's
a pre-print, just publish a link to it. But there are already plenty of
examples in the published literature if you are looking for evidence of
regression.

So where are the Apologies? There are none :-) Excuse me is what people
say when they elbow their way through a crowd. (I only do that when I
really need to). So if you really need to attach a document, go ahead.
After all, you can still read the list on the archive.

Alan
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++



Re: clay mineral samples - illite - interstratified minerals

2015-04-24 Thread Alan Hewat
 I allowed myself to attach DOC files...


Sorry Łukasz, it is NOT allowed to attach files to everyone on the mailing
list. Instead, put them on a file hosting service and simply post a link -
see: http://en.wikipedia.org/wiki/Comparison_of_file_hosting_services

Since you must be aware of this rule, which is stated in the footer to
every message, you will be temporarily suspended from the list.

Alan.
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++



Re: isotropic displacement parameter

2014-11-02 Thread Alan Hewat
If your refinement looks good it doesn't necessarily mean your model is
true, just that you have a lot of parameters :-)

Negative temperature factors mean that your refinement is trying to add
intensity at high angles, the opposite of the temperature effect. This may
mean that you haven't corrected for absorption, which for small values is
the equivalent of an overall  negative temperature - eg see: factor
http://scripts.iucr.org/cgi-bin/paper?a16955

Unfortunately there is an error of a factor of two in that paper :-)

Alan

On 1 November 2014 19:08, Rachid Abkar rachid.ab...@gmail.com wrote:

 The Biso isotropic displacement parameter of each element in my refinement
 using fullprof is over 3 and negative ? but my refinement  looks good and
 Rwp is only 9 could anybody give me some advice Thanks sincerely

 *ABKAR RACHID*

 ++
 Please do NOT attach files to the whole list alan.he...@neutronoptics.com
 
 Send commands to lists...@ill.fr eg: HELP as the subject with no body
 text
 The Rietveld_L list archive is on
 http://www.mail-archive.com/rietveld_l@ill.fr/
 ++





-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++



Re: 1-Adamantanol

2014-10-25 Thread Alan Hewat
Sigh ! How can we stop people posting files to all 2000+ members of the
Rietveld list when there is a warning not to do so at the end of every
message ?

And frankly, databases like CCDC cost money and effort to produce. If you
want to use them, please consider asking your laboratory to subscribe
rather than asking Rietveld list users to break their conditions of use by
copying and publishing their content.

Alan


2014-10-25 1:09 GMT+02:00 Cristóbal Verdugo cverdu...@gmail.com:

   Dear David,

 find attached the .cif of 1-Adamantanol from CCDC.

 Regards,

 Cristóbal


 — Dr. Cristóbal Verdugo Escamilla Laboratorio de Estudios Cristalográficos
 Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR) Avda. las Palmeras, 4
 18100 Armilla, Granada Spain Phone. +34 95823 Ext. 190009
 cristobal.verd...@csic.es

 On viernes, oct 24, 2014 at 4:10 p. m., David MARTINEZ BLANCO 
 martinezbda...@uniovi.es, wrote:

  Dear Rietvelders,



 Can anyone provide me cif files with the structure of 1-Adamantanol (
 C10H16O)?



 Thanks in advance,

  Kind Regards,

  David





 Dr. David Martínez Blanco.

  Técnico de la Unidad de Medidas Magnéticas

  Servicios Científico-Técnicos, Universidad de Oviedo

  Escuela Politécnica de Mieres

  C/ Gonzalo Gutiérrez Quirós, sn

  33600, Mieres (Asturias), SPAIN.

  Tel.: (+34) 985 45 8000 (Ext.5824)

  Móv.:  (+34) 656 270 659

  martinezbda...@uniovi.es

  ADVERTENCIA DE CONFIDENCIALIDAD

  Este mensaje ha sido enviado para uso exclusivo de la persona o entidad
 que figura en el mismo como destinatario, conteniendo información
 confidencial y protegida. Cualquier distribución, transmisión, copia, uso o
 aprovechamiento no autorizado de la información contenida en el mismo, es
 absolutamente ilegal, quedando prohibida expresamente por la Ley Orgánica
 15/1999, de Protección de Datos de Carácter Personal. Si usted no es la
 persona interesada o el receptor al que va dirigido este correo, por favor,
 comuníquelo a la mayor brevedad posible, por medio de llamada telefónica,
 fax o por este mismo medio, procediendo a la destrucción inmediata de este
 mensaje. Gracias.




 ++
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 Send commands to lists...@ill.fr eg: HELP as the subject with no body
 text
 The Rietveld_L list archive is on
 http://www.mail-archive.com/rietveld_l@ill.fr/
 ++





-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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++



Re: Historical Tutorial

2014-08-06 Thread Alan Hewat
Laurie. Google is your friend. First Google Scholar to find A. F.
Gultieri is still publishing and still at Modena, and then Google the name
with the university and you immediately find him:
http://personale.unimore.it/rubrica/dettaglio/alex
His email address has changed :-)

Alan


On 6 August 2014 02:11, Laurie Aldridge laurie.aldri...@gmail.com wrote:

 I am trying to fit a pattern with an amorphous hump for quantitative phase
 analysis and found a web report on
 http://www.ccp14.ac.uk/solution/gsas/files/expgui_quant_gualtieri.pdfA
 guided training exercise of quantitative phase analysis using EXPGUIA. F.
 Gualtieri Dipartimento di Scienze dellla Terra, Università di Modena e
 R.E.Via S.Eufemia 19, 41100 Modena, ITALY E-mail:a...@unimo.it -
 www.terra.unimo.it

 I have tried to contact the author but have had no reply

 Does anyone know if there is any other source of this tutorial data?

 --
 Laurie Aldridge
 24 Balmer Cres
 Woonona 2517 NSW
 Australia

 Email laurie.aldri...@gmail.com
 Phone +61 (2) 4284 0132
 Mobile 0403 718 522

 ++
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 text
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 ++





-- 
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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++



Re: information for rietveld refinement

2014-07-16 Thread Alan Hewat
 Im student researcher I need  a guidelines for refinement structure
double perovskite
 using fullprof or other software in case to reduce Factors and than draw
structures

Dear Colleague.

It is difficult to reply to such a general query. You could start by
reading the FullProf manual and tutorials on
https://www.ill.eu/sites/fullprof/php/tutorials.html :-)

The first question is the symmetry (space group). Do a google search for:
https://www.google.com/webhp?q=%22double+perovskite%22+symmetry
Then look in particular at the free articles on http://www.researchgate.net/
(3rd link)

To search for examples of double perovskites, try http://www.ill.fr/ Log on
as demo and search for Element=O6 and ElementCount=3 i.e.
http://icsd.ill.eu/icsd/index.php?action=Searchelements=o6elementc=3

If you then click on the formula eg Cu (Nb2 O6) the structure will be drawn
using Java in a new window. (You must install Java in your browser and give
it permission to run).

You can download the CIF files, calculate bond lengths, draw the powder
patterns etc by clicking on those buttons.

I hope this will get you started, but then I suggest you join the Rietveld
mailing list, which has over 1000 members who can advise you about specific
problems. To join, send an email to lists...@ill.fr with the title:
SUBSCRIBE Rietveld_L your name and lab

With kind regards, Alan Hewat (Rietveld list manager)
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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++



Ecole MICO multidisciplinaire sur des systèmes à fortes corrélations électroniques

2014-03-05 Thread Alan Hewat
*Ecole MICO *Le groupement de recherches Matériaux et Interactions en
Compétitions (GdR MICO) et l'Institut Laue Langevin (ILL) organisent une
école sur les concepts nécessaires à l'étude multidisciplinaire des
systèmes à fortes corrélations électroniques.  Elle aura lieu
 *du dimanche 25 mai au samedi 31 mai 2014 à l'Institut Laue Langevin à
Grenoble*
Les inscriptions sont ouvertes dès maintenant sur le site du GdR et
jusqu'au 18 avril
*http://gdr-mico.cnrs.fr/spip.php?rubrique117
http://gdr-mico.cnrs.fr/spip.php?rubrique117*

Vous pouvez télécharger l'affiche sur le site du GdR (
http://gdr-mico.cnrs.fr/). N'hésitez pas à la diffuser

Les frais de participation comprennent l'accès aux cours et l'hébergement
en pension complète.
Ils sont fixés à 250 euros HT/ 300 euros TTC (subvention d'environ 50% du
coût grâce au GdR, à l'ILL et à nos sponsors).

Des visites de l'ILL/ Néel/LNCMI et peut-être ESRF sont prévues, si vous
êtes intéressés, n'oubliez pas de le signaler dans votre formulaire
d'inscription.

Le programme comprendra les cours suivants

   1. Outils de base : cours de mise à niveau facultatifs
   - 1h : Brigitte Leridon : * La seconde quantification*
  - 3h : Benjamin Canals :  *Notions de base de théorie des groupes*
  - 3h : Marie-Bernadette Lepetit : *Calculs ab initio pour les nuls
  (TP sur un code)*
2. Concepts fondamentaux
   - 2h : Marie-Bernadette Lepetit : *De l'atome à la structure de
  bande en passant par les interactions magnétiques*
  - 2h : Marc Gabay : *Transitions de phases (aspets microscopiques et
  phénoménologiques, champ moyen, théorie de Landau)*
  - 2h : Brigite Leridon : *Supraconductivité conventionnelle (théorie
  BCS)*
  - 3h : Fabrice Bert : *Magnétisme : états fondamentaux (FM, Ferri,
  AFM, PM), excitations élémentaires (ondes de spin)*
  - 2h : Béatrice Grenier : *Cristallographie et techniques
  expérimentales associées*
  - 2h : Laurent Cario : Grandes classes de composés à propriétés
  électroniques remarquables
 3. Cours avancés : Focuss
   - 1h : Marc Gabay : *Transitions de phases : au delà de
  Landau (points critiques quantiques, lois d'échelle, zones de
fluctuation,
  cross-over)*
  - 2h : Yann Gallais : *Supraconductivité non conventionnelle*
  - 2h : Werner Paulus : *Non stoechiométrie, désordre et substittutions*
  - 1h : Julien Robert : *Magnétisme avancé (liquide, verre, glaces de
  spin, frustration versus désordre)*
  - 2h : Ricardo Lobo : *Les multiferroïques*
4. Techniques d'investigation de la matière
   - 1h00 : Pierre Bordet : *Quelle technique expérimentale pour quelle
  information ?*
  - 1h30 : Marino Marsi :Dynamique ultrarapide étudiée par ARPES
  - 1h30 : Sylvain Petit :* Neutrons Inélastiques*
  - 1h30 : Vinh TaPhuoc : *Conductivité optique (statique + résolue en
  temps)*
  - 1h30 : Andrei Rogalev : *Sondes locales (Xanes Exafs XMCD)*
5. Exposés d'ouverture
   - 1h : David Carpentier : *Isolants topologiques*
  - 1h : Nathalie Viart : *Les méthodes de synthèse ou élaboration de
  matériaux.*

__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
++
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++



Re: NAC standard

2014-03-03 Thread Alan Hewat
On 3 March 2014 12:30, Tomce Runcevski t.runcev...@fkf.mpg.de wrote:

 ...don't breathe it in, don't eat, nor drink, and wear safety glasses,...
 Lovely :)


OK :-)  AVOID breathing it in, don't eat, nor drink IN A LABORATORY, and
wear safety glasses...

It's not a joke. Those precautions should be second nature, especially in a
chemistry or radiation laboratory.

Alan
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Re: Post doctoral Fellowship Opportunity

2014-02-09 Thread Alan Hewat
Sigh... Does no-one read the note at the bottom of every post about not
sending files to all 2000 members of the Rietveld list ? Do people not have
web sites they can post such things to, with a simple email link pointing
to them ?
Alan

From my telephone
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On 10 Feb 2014 06:42, Dave Billing dave.bill...@wits.ac.za wrote:

  Morning All,



 Please find attached an advertisement for a Post-Doctoral fellowship that
 I would like to fill as soon as possible, ideally before the end of the
 month.



 Should there be any questions then please do not hesitate to contact me.



 Best regards



 Dave Billing





 Prof. D.G. Billing
 School of Chemistry.
 University of the Witwatersrand.
 Private Bag 3.
 Wits 2050.
 South Africa

 Tel no : +27 11 717 6759

 Fax2email : +27 086 553 5259
 Fax no:  +27 11 717 6749
 e-mail : dave.bill...@wits.ac.za



 This communication is intended for the addressee only. It is confidential. If 
 you have received this communication in error, please notify us immediately 
 and destroy the original message. You may not copy or disseminate this 
 communication without the permission of the University. Only authorised 
 signatories are competent to enter into agreements on behalf of the 
 University and recipients are thus advised that the content of this message 
 may not be legally binding on the University and may contain the personal 
 views and opinions of the author, which are not necessarily the views and 
 opinions of The University of the Witwatersrand, Johannesburg. All agreements 
 between the University and outsiders are subject to South African Law unless 
 the University agrees in writing to the contrary.


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Evaporation of aluminium windows onto x-ray scintillators ?

2014-01-30 Thread Alan Hewat
Apologies for this naive non-Rietveld question, but there are many x-ray
experts here :-)

Normally people use al-mylar, beryllium or other low absorbing x-ray
windows, but these can be rather fragile. What about evaporating a thin
layer of aluminium directly onto the scintillator? A smooth plastic x-ray
scintillator  would be robust enough by itself if light could be excluded
from one side with some kind of x-ray transparent coating. (At present I
use thin carbon-fibre x-ray windows for large areas -
http://neutronoptics.com/laue.html - but there is still some attenuation.

Alan
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Re: Debye 1915 paper

2013-12-26 Thread Alan Hewat
Google shows these old papers were put on line in 2006 by Wiley - but they
want you or your library to subscribe and pay for them:-) Surprising when
politicians are pressing for free open access to new work.

Happy New Year to all. Alan

From my telephone
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On 26 Dec 2013 23:34, Enyuan Hu bearcha...@gmail.com wrote:

 Dear all,

 I've been looking for English translated Debye's 1915 paper Zerstreuung
 von Röntgenstrahlen (scattering of x-rays) but didn't succeed. Does
 anyone have this collection and would like to share? Thanks.

 Enyuan

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Searching PDF files that cannot normally be searched.

2013-12-20 Thread Alan Hewat
 Thanks.  It seems I should learn how to use the search function in my PDF
 reader.


Unfortunately many PDF files cannot be searched because they contain only
an image of the text, not the actual text. This is apparently not the case
for TOPAS help files, but it is useful to know how to search files that
contain only text images i.e. many PDF files on the web. (Google can search
such files).

Adobe Acrobat (not Adobe Reader) can do OCR character recognition of image
only PDF files and store the text version that can then be searched with
Ctrl-F. Acrobat also allows you to print searchable PDF files from Word
and other applications. Acrobat is expensive, but you can download and
install an obsolete but fully functional version 8 from the Adobe site
for free - see:
http://blog.stead.id.au/2013/01/installing-adobe-acrobat-pro-8-on.html

People producing help files should ensure that they are searchable.
Microsoft still does not provide PDF print capability, so you need to
install Acrobat or a free PDF printer see:
http://www.howtogeek.com/150891/how-to-print-to-pdf-in-windows-4-tips-and-tricks/
Yes
I know that you don't need such tricks with other operating systems :-)

Just a little end-of-year diversion from the usual Rietveld exchanges :-)
Alan.
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Re: X-ray diffraction laboratory manager position

2013-12-06 Thread Alan Hewat

 Could beam line scientists be described as lab technicians? Not if you
 hope to return and get help with your next synchrotron/neutron experiment!


I hope that's not the only reason :-) Good to see some end-of-year banter
on the Rietveld list. As Leonid shows, in Europe titles are important. But
in the US asking for a Ph.D. simply indicates the level of experience
required. Otherwise a person is judged on his performance not his title.

Talking of screwdrivers, when I worked in the UK (some time ago) scientists
weren't supposed to know how to use them. Technicians performed experiments
and scientists analysed and published the results. This attitude still
colours relations at large scale user facilities.

Alan
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The PANalytical Award

2013-09-05 Thread Alan Hewat
*The PANalytical Award*

With the yearly PANalytical Award the company seeks to encourage and
provide support for excellent young scientists who are at the beginning of
their careers. The award recognizes and praises groundbreaking research
that required the use of a laboratory X-ray diffraction, X-ray fluorescence
or X-ray scattering instrument as the primary analytical technique. As
such, recipients will not be limited to any brand of instrument, but rather
to research that utilised an X-ray source to reach their conclusions.
The award

The annual award consists of a *€ 5 000* cash prize, a trophy and a
certificate. The award is presented yearly at an event that is still to be
confirmed.

http://www.panalytical.com/en/Events-overview/The-PANalytical-Award.htm
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Re: Unrestrained SDPD future

2013-08-09 Thread Alan Hewat
 http://dx.doi.org/10.1107/S1600536813017522
 proposed as an instance of the SDPD future trend

Fortunately this short paper is open access.
http://journals.iucr.org/e/issues/2013/07/00/vn2075/vn2075.pdf

It is truly a tour de force to quote N-H bonds determined to 3
significant figures from a heavy atom compound with one axis as long
as 17.5 Angstroms - by x-ray powder diffraction !

The future isn't what it used to be (Paul Valery, French poet)

Alan
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Re: [sdpd] Re: Are restraints as good as observations ?

2013-08-08 Thread Alan Hewat
The week is up, and restraints on posting to this topic have been
relaxed :-) Restraints were imposed, not because it had become a
tedious ping-pong match with each trying to have the last word, but
because it had degenerated into name-calling. Implying that your
opponent is a liar, a pestilence or brain dead precludes
dispassionate argument on an important subject. (The latest name was
Siberian Troll, which may have been an attempt at humour :-)

If people feel they have missed something, there are another couple of
dozen exchanges on the SDPD list under the heading The future of
SDPD. In the end, both parties agreed that they never said the more
restraints the better.

The most interesting new contribution was to point out that when
restraints are used in Shel-X, a final cycle without restraints and
damping is recommended to obtain better estimates of ESD's.
Unfortunately people are unlikely to do that if it gives
unreasonably large ESD's.

Alan.

 From absurdity and crimes we arrived at falsifications?
 Ugly yours, with pestilence,
 PS- rigid brain is the first step before rigid body

 OK, I asked people to stop this argument. The essential points have
 been covered, so I am restraining the two principal antagonists from
 posting for a 1 week relaxation period :-) Please email me personally
 if you don't agree.
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Restraints on posting to the Rietveld list

2013-08-02 Thread Alan Hewat
 From absurdity and crimes we arrived at falsifications?
 Ugly yours, with pestilence,
 PS- rigid brain is the first step before rigid body

OK, I asked people to stop this argument. The essential points have
been covered, so I am restraining the two principal antagonists from
posting for a 1 week relaxation period :-) Please email me personally
if you don't agree.
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Re: Help with parts for of an old Philips 1055/81 goniometer ?

2013-08-02 Thread Alan Hewat
Thanks to all who replied about this, and in particular to those who
offered parts and suggested that Hiltonbrooks (UK) had such spare
parts for old equipment - http://www.xrays.u-net.com. My colleague now
thinks his workshop might be able repair the original piece, so is
holding off on following up on your suggestions that I forwarded to
him.

Alan

On 1 August 2013 01:08, Alan Hewat alan.he...@neutronoptics.com wrote:
 A colleague asks if anyone can help him with the rotating sample
 compartment of an old Philips 1055/81 goniometer ? He badly needs this
 part since the company (Panalytical) say they no longer support this
 very old system.
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Re: [sdpd] Re: Are restraints as good as observations ?

2013-08-01 Thread Alan Hewat
 At the end it is all wrong as we don’t refine individual electrons...

I think we have heard enough when the argument turns to Reductio ad absurdum

You might also say that Rietveld refinement by its nature is
restrained because we restrain the peaks to positions that are
determined by the the assumed average crystal lattice. We could
otherwise, and do with PDF analysis, simply Fourier transform the
diffraction pattern to obtain the pair correlation pattern, which in
the end is the only real-space information available. As Leonid says,
in some cases we might even try to determine the electron
distribution.

But there is a difference when we publish a structure as a Rietveld
Refinement, when in fact most of the information comes from
restraints and not measured data. Yes if you have a complex structure
and relatively poor data, you might want to restrain your model in
order to say something about it. But the most you can then say is that
the restrained model is consistent with the data. As Leonid says, when
you restrain parameters in your model that would otherwise correlate
with refined parameters (that is why you restrain them), the
calculated standard deviations of the remaining refined parameters are
underestimated (not improved).

FYI: The greater restraints to parameters ratio the better. AT the end 
restraints are observations. S it is not about restraints...

That was the statement that shocked me :-) and which started this
unfortunate thread.

As for x-ray powder refinements of heavy metal oxides, there are over
60 entries in ICSD for Mo-oxides. These oxides are often
non-stoichiometric, probably due to mixed valence, have various phases
or even mixed phases and even non-commensurate phases (actually
block structures of different stoichiometry). Such materials are
difficult to study with x-rays anyway, because of the heavy atoms as
well as all kinds of x-ray powder experimental problems, including of
course the powder averaging itself.

When Armel praises such x-ray powder refinements as the most complex
yet attempted, I suspect he is being a little sarcastic :-) Much as I
admire Rietveld refinement, there are some problems for which it is
simply not suitable. Hugo Rietveld himself thought that it would never
be applied for x-rays because of the systematic errors, but of course
he was wrong :-) People are happy now to apply black box Rietveld
programs, refining all kinds of sophisticated sample-experiment
corrections to improve their R-factor, and then having to add
constraints to ensure that the resulting structure looks good enough
to publish. OK, but when they say that the more restraints the better,
some of us don't agree. Let's leave it at that.

Alan
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Archive of Rietveld messages

2013-07-31 Thread Alan Hewat
Many of us have our own archive of Rietveld messages, since mail
servers never forget anything we write or receive these days - they
are not allowed to :-)

But the public archive on
http://www.mail-archive.com/rietveld_l@ill.fr/maillist.html was useful
for newcomers and for people having trouble receiving the list
emails... until it stopped working following an update of the SYMPA
software that runs it. SYMPA now defaults with a header X-no-archive:
yes and even if you try to over-ride that with another header
X-no-archive: no, messages are discarded by mail-archive.com as soon
as the first default header is found. The argument for the new default
behaviour was that individuals could retract their messages from SYMPA
(I'm not sure how, since they are immediately distributed) and they
can't easily remove messages from a public WWW site (but see:
http://www.mail-archive.com/faq.html#delete ).

Thanks to Stephane Armanet at ILL, we think we have solved this
problem, and this message and all future messages to the Rietveld_L
list should appear on
http://www.mail-archive.com/rietveld_l@ill.fr/maillist.html

Alan
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Help with parts for of an old Philips 1055/81 goniometer ?

2013-07-31 Thread Alan Hewat
A colleague asks if anyone can help him with the rotating sample
compartment of an old Philips 1055/81 goniometer ? He badly needs this
part since the company (Panalytical) say they no longer support this
very old system.
__
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
alan.he...@neutronoptics.com +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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Re: *.cif files for RMnO3 (R= Sm,Eu,Gd,Dy,Ho,Yb)

2010-03-13 Thread Alan Hewat
You can get a access to a limited time account for the Inorganic Crystal
Structure Database ICSD from http://icsd.fiz-karlsruhe.de/

You should check with your University library whether they have permanent
access to this database; you may only want a few structures now, but you
will certainly want others in future.

sisir ray said:
 Dear Dr. Putz,
 Thank you very much for the information.I tried the Demo version and it is
 wonderful.However it does not show the *.cif files I need.
 Is there any way I can purchase only the individual RMnO3 *.cif files
 instead of paying for the full price for all the * .cif files as I want
 only
 the RMnO3 ones.

 Best regards
 Shishir Ray

 On Fri, Mar 12, 2010 at 1:22 AM, Holger Putz (Crystal Impact) 
 p...@crystalimpact.com wrote:

 Dear Shishir Ray,

 in the current release of Pearson's Crystal Data (
 http://www.crystalimpact.com/pcd), there are 29 entries that match your
 criteria, describing seven different orthorhombic phases. 10 entries
 originate from papers that were published in 2005 or later.

 Best regards
 Holger Putz

  Am 11.03.2010 um 21:09 schrieb sisir ray:

  Dear Rietveld community,
 I am looking for the latest *.cif files for RMnO3 (R =
 Sm,Eu,Gd,Dy,Ho,Yb)
 compounds in orthorhombic and hexagonal phases .Can any body suggest
 where I
 can find them.
 I really appreciate the help.

 Thank you

 Best
 Shishir Ray
 Graduate student
 University of Wisconsin Milwaukee


   ***
 Dr. Holger Putz
 Crystal Impact
 Dr. K. Brandenburg  Dr. H. Putz GbR
 Rathausgasse 30
 53111 Bonn
 Germany

 Tel . : +49-228-9813643
 Fax   : +49-228-9813644
 E-mail: p...@crystalimpact.com
 Web   : http://www.crystalimpact.com
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RE: Negative Uiso in GSAS

2010-03-04 Thread Alan Hewat
Michael Glazer said:
 Rietveld refinement (as opposed to single-crystal refinement) is in fact
 refinement of degraded data (it is one-dimensional instead of
 three-dimensional) and so the errors will be more significant.

While I agree with Mike's list, I can't let him get away with such a
sweeping statement implying that single crystal refinements necessarily
give better structures, simply because the data is three dimensional.

Errors in crystal refinement arise from all kinds of effects apart from
problems due to overlapping peaks. Extinction is a cause for error that is
usually more serious for single crystals than for powders - especially
with strain associated with a structural transition. Texture is a problem
associated mainly with X-ray powder diffraction etc...

With todays high resolution powder diffractometers and Rietveld
refinement, I don't even believe that overlapping reflections from one
dimensional data is the main cause of error. Its true that if peaks are
strongly overlapping at high angles then refining the background may
result in it being overestimated, leading to higher temperature factors.
Refinement of absorption will also strongly correlate with temperature
factors.

That is why you should not keep adding more parameters such as background,
absorption etc simply to obtain a lower R-factor and expect that to equate
to a better structure determination. You should try to actually measure
these other effects and correct for them, not simply refine them away.
__
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