Re: Rietveld ESD calc fortran code typo?

Thanks a lot for that Jonathon. The code is helping me understand the algorithm, in particular the implementation of the double sum. Currently in the process of reproducing it in python to get around my essentially complete lack of knowledge in fortran so I can properly understand it. On Thu,

Re: Rietveld ESD calc fortran code typo?

Dear Matthew That fortran snippet was corrected in Appendix 1 of Andreev's paper here: https://doi.org/10.1107/S002188989300891X It is a shame that implicit none was not part of fortran 77. The google search resul leading me to that was:

Re: Rietveld condamnation considered as established by some more people

factors. Then comes the Rietveld refinement anyway.envoyé : 18 août 2023 à 17:00de : Alan W Hewat à : Le Bail Armel cc : "rietveld_l@ill.fr" objet : Re: Rietveld condamnation considered as established by some more peopleI have no problem with Rietveld's prize Armel. Crystallographers i

Re: Rietveld condamnation considered as established by some more people

W Hewat > *à :* Le Bail Armel > *cc :* rietveld_l@ill.fr > *objet :* Re: Rietveld condamnation considered as established by some > more people > > Bonjour Armel. > > No, it was van Laar who initiated it. He was annoyed that I had praised > Rietveld too much in my own accou

Re: Rietveld condamnation considered as established by some more people

août 2023 à 11:30de : Alan W Hewat à : Le Bail Armel cc : rietveld_l@ill.frobjet : Re: Rietveld condamnation considered as established by some more peopleBonjour Armel.No, it was van Laar who initiated it. He was annoyed that I had praised Rietveld too much in my own accounts. http://hewat.net/science

Re: Rietveld condamnation considered as established by some more people

ase) decomposition formula ? envoyé : 16 août 2023 à 19:08 de : Alan W Hewat mailto:alan.he...@neutronoptics.com>> à : Le Bail Armel mailto:le-bail.ar...@orange.fr>> cc : "rietveld_l@ill.fr<mailto:rietveld_l@ill.fr>" mailto:rietveld_l@ill.fr>> objet : Re: Rietve

Re: Rietveld condamnation considered as established by some more people

S - Why to insert a reference to the 1981 Pawley paper in a 1988 paper > where his > > method was not used but another method much later named "Le Bail method" > and > > based on the Rietveld (Loopstra ??? proove it please) decomposition > formula ? > > *envoyé :* 16

Re: Rietveld condamnation considered as established by some more people

on formula ?envoyé : 16 août 2023 à 19:08de : Alan W Hewat à : Le Bail Armel cc : "rietveld_l@ill.fr" objet : Re: Rietveld condamnation considered as established by some more peopleBonjour Armel. In answer to your question "Where did they find the text of the judgement ?" please

Re: Rietveld condamnation considered as established by some more people

My personal feelings are that regardless of the origin of the idea, Hugo did the work that made crystallographic full pattern fitting possible. That implementation was not just a “programming task” as the minimal capabilities of computers of the day required significant innovation for memory

RE: Rietveld condamnation considered as established by some more people

/watch?v=WsPBB6azzX4 From: rietveld_l-requ...@ill.fr On Behalf Of Alan W Hewat Sent: Thursday, August 17, 2023 5:40 PM To: Le Bail Armel Cc: rietveld_l@ill.fr Subject: Re: Rietveld condamnation considered as established by some more people Armel, it's not about you :-) But in your 1988 paper y

Re: Rietveld condamnation considered as established by some more people

Dear Luca. Since I administer the Rietveld mailing list, I could have changed the name years ago when Van Laar and Schenk published their history, with which I largely sympathise. I didn't, because everyone now calls it "Rietveld Refinement", a name invented by Terry Sabine, who worked with

Re: Rietveld condamnation considered as established by some more people

Given the involvement of Alan in the early days I would be confident to trust his view. So why we don't try to fix a bit the mistake. We could: - start renaming this list as Loopstra-Rietveld list ;-) ( I would keep the name Rietveld in hit, first who got the idea, second the programmer) -

Re: Rietveld condamnation considered as established by some more people

Armel, it's not about you :-) But in your 1988 paper you did not reference Pawley (1980) and even Rietveld only appeared as #14 https://www.researchgate.net/publication/228084768_Ab_Initio_Structure_Determination_of_LiSbWO6_by_X_ray_Powder_Diffraction#fullTextFileContent But let's not change the

Re: Rietveld condamnation considered as established by some more people

It's a widespread phenomenon. What about America being named for Vespucii rather than Columbus? On Thu, 17 Aug 2023, 11:49 Le Bail Armel, wrote: > >And there are other examples. See this brief review of "Whole Pattern > Fitting - The Pawley Method" (1980) yet few people now attribute this kind

Re: Rietveld condamnation considered as established by some more people

>And there are other examples. See this brief review of "Whole Pattern Fitting - The Pawley Method" (1980) yet few people now attribute this kind of profile refinement to Pawley. http://pd.chem.ucl.ac.uk/pdnn/solve1/pawley.htmFew people ? At least me

Re: Rietveld condamnation considered as established by some more people

And there are other examples. See this brief review of "Whole Pattern Fitting - The Pawley Method" (1980) yet few people now attribute this kind of profile refinement to Pawley. http://pd.chem.ucl.ac.uk/pdnn/solve1/pawley.htm On Wed, 16 Aug 2023 at 19:33, wrote: > Le Bail Armel schreef op

Re: Rietveld condamnation considered as established by some more people

Le Bail Armel schreef op 2023-08-16 18:45: In a book : HOW SCIENCE RUNS – IMPRESSIONS FROM A SCIENTIFIC CAREER. BY ERIC J. MITTEMEIJER Reviewed by Mike Glazer "In another section, the author has some criticism about the famous Rietveld method in powder diffraction. He points out that

Re: Rietveld condamnation considered as established by some more people

Bonjour Armel. In answer to your question "Where did they find the text of the judgement ?" please see: "The development of powder profile refinement at the Reactor Centre Netherlands at Petten" Bob van Laar and Henk Schenk https://scripts.iucr.org/cgi-bin/paper?ib5058 Van Laar worked at Petten

Re: Rietveld website cancelled ?

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 :-)

Re: Rietveld website cancelled ?

ssage du 29/08/18 12:33 > De : "Alan Hewat" > A : "Armel Le Bail" > Copie à : "rietveld_l@ill.fr" > Objet : Re: Rietveld website cancelled ? > > > A clear distinction having my complete agreement. (Armel) Ouf. Nous sommes d'accord enfin :-) For

Re: Rietveld website cancelled ?

eld_l@ill.fr" > Copie à : > Objet : Re: Rietveld website cancelled ? > > > You dig ! Please stop digging Armel. Loaded guns, grave digging and religion are off limits. __ >    Dr Alan Hewat, NeutronOptics, Gr

Re: Rietveld website cancelled ?

> You dig ! Please stop digging Armel. Loaded guns, grave digging and religion are off limits. __ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * +33.476.98.41.68 http://www.NeutronOptics.com/hewat

Re: Rietveld website cancelled ?

j" > A : "% MailingList Rietveld" > Copie à : elb...@jhu.edu > Objet : Re: Rietveld website cancelled ? > > It all depends on the definition. If/when we agree on the definition, there is usually no points for further arguing. Anyway we could call Relieved metho

RE: Rietveld website cancelled ?

mind and a lot of chance- congratulations.   You dig.   Armel     > Message du 29/08/18 18:26 > De : "Von Dreele, Robert B." > A : "Larry Finger" , "Le Bail Armel" , "Toby, Brian H." > Copie à : "Rietveld_L@ill.fr" > O

Re: Rietveld website cancelled ?

Was that Clint Eastwood? - Kurt From: rietveld_l-requ...@ill.fr on behalf of Le Bail Armel Sent: Wednesday, August 29, 2018 12:01:25 PM To: Rietveld_L@ill.fr Subject: Re: Rietveld website cancelled ? OK, seems that the SDPD book preface looks unclear to some

Re: Rietveld website cancelled ?

On 08/29/2018 02:01 PM, Le Bail Armel wrote: OK, seems that the SDPD book preface looks unclear to some. Western movies adepts well know that sentence : "You see, in this world there's /two kinds/ of /people/, my friend: /those/ with loaded /guns/, and /those/ who /dig/. /You dig/. .."

Re: Rietveld website cancelled ?

believing that the sense of the words "structure determination" and "structure refinement" are the same, and the others. You dig.   Best   Armel         > Message du 29/08/18 18:09 > De : "Larry Finger" > A : "Le Bail Armel" , Ri

Re: Rietveld website cancelled ?

It all depends on the definition. If/when we agree on the definition, there is usually no points for further arguing. Anyway we could call Relieved method a structure determination from powder data as long as it does not included solving structure (or as David elegantly put - true structural

RE: Rietveld website cancelled ?

. NB: this kind of thing has also happened more recently (see papers by Margiolaki, et al). Bob Von Dreele -Original Message- From: rietveld_l-requ...@ill.fr On Behalf Of Larry Finger Sent: Wednesday, August 29, 2018 11:10 AM To: Le Bail Armel ; Rietveld_L@ill.fr Subject: Re: Rietveld web

Re: Rietveld website cancelled ?

On 08/29/2018 04:15 AM, Le Bail Armel wrote: Hi, After the IUCr Monograph on Crystallography 13 (2002) entitled "Stucture Determination from Powder Diffraction Data" you may find in the preface : "Although the Rietveld method of structure refinement from powder diffraction data is often

Re: Rietveld website cancelled ?

ies that the structure is already determined (not always if you use ICDD), then if you wish, you may refine it by the Rietveld method     > Message du 29/08/18 12:35 > De : "Alan Hewat" > A : "Armel Le Bail" > Copie à : "rietveld_l@ill.fr" > Objet :

Re: Rietveld website cancelled ?

> A clear distinction having my complete agreement. (Armel) Ouf. Nous sommes d'accord enfin :-) For Armel, here are a couple of examples of automatic indexing, search-match and structure

RE: Rietveld website cancelled ?

agreement.   Armel http://www.cristal.org/CAC-XX/maze.jpg http://www.cristal.org/CAC-XX/Rietveld.ppt     > Message du 29/08/18 10:14 > De : "May, Frank" > A : "Alan Hewat" , "rietveld_l@ill.fr" > Copie à : > Objet : RE: Rietveld website cancelled

RE: Rietveld website cancelled ?

To all: Initially I sent this to Alan who suggested I open discussion to the entire community. I've posted similar in past years and have been FLAMED. Please keep it civil. ;-) = As a long time practitioner of powder XRD (since 1972) I was there when the superconductor

Re: Rietveld website cancelled ?

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:

Re: Rietveld

*> 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. __ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * +33.476.98.41.68

Re: Rietveld

hod and not his 1967 or 1969 papers. Rietveld's real number of citations is probably closer to >40.000 than to 15.000. But you know that already...   Best,   Armel         > Message du 22/08/18 14:23 > De : "Alan Hewat" > A : "rietveld_l@ill.fr" > Copie à :

Re: Rietveld

*> Another example.. Loopstra, van Laar and Breed Physics Letters 26A(11) 1968, 526* (AleB) Examples are easy. In Gibaud, Le Bail and Bulou J. Phys. C: Solid State Phys. 19 (1986) 4623 "*...the Rietveld program modified by Le

[SUSPECTED SPAM] Re: Rietveld

>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) In the Introduction of Loopstra and Rietveld (1969) they referred to the approach as "the profile

Re: Rietveld

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

Re: Rietveld

>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". It seems that the basic collision is in the absence of strict and commonly accepted definition of the 'Rietveld Method' term. Does

Re: Rietveld

*> 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

RE: Rietveld

ven to Rietveld for developing and distributing his software; if more was done by Rietveld in regards to developing f then all the better. All the best Alan Coelho From: rietveld_l-requ...@ill.fr On Behalf Of Scott Speakman Sent: Wednesday, 22 August 2018 4:35 AM To: Rietveld_l@ill.fr Subje

Re: Rietveld

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:

Re: Rietveld

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

RE: Rietveld

e want to do business: The value of Integrity - Code of Business Ethics<http://www.spectrisethics.co.uk/MAL/> From: rietveld_l-requ...@ill.fr On Behalf Of Le Bail Armel Sent: Tuesday, August 21, 2018 11:09 AM To: Rietveld_l@ill.fr Subject: Re: Rietveld The >1500 subscribers can vote... :

Re: Rietveld

The >1500 subscribers can vote... :   https://doodle.com/poll/gh3v3nfhue599w23   Best,   Armel       > Message du 21/08/18 19:10 > De : "Alan Hewat" > A : "rietveld_l@ill.fr" > Copie à : > Objet : Re: Rietveld > > > As a matter

Re: Rietveld

*> 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

Re: Rietveld

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

Re: Rietveld

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 <mailto:Rietveld_l@ill.fr> *Subject:* Re: Rietveld *>"...*/*the method did not suddenly appear in a flash of

Re: Rietveld

o.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 > > > &g

RE: Rietveld

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

Re: Rietveld

Seems that Rietveld had not the same opinion and claimed for ideas too and possibly for mathematics as well. Best, Armel Armel, For the sake of the scientific exchange of ideas and facts, too bad that Dr. Rietveld is not alive. Regards, Miguel Delgado On 8/19/2018 6:21 PM, Le Bail

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

Re: Rietveld

> Seriously, HS really think that Hugo Rietveld had absolutely no idea, and then worked out mathematically nothing ? Armel, the vL paper doesn't say that Rietveld had no idea and contributed nothing. Please read the first line of the paper

Re: Rietveld

order to contradict the legend and has done nothing apart using the method and citing quietly the 1969 paper from Hugo Rietveld.   Best,   Armel             > Message du 18/08/18 12:24 > De : "Alan Hewat" > A : le-bail.ar...@orange.fr > Copie à : "rietveld_l

Re: Rietveld

*> 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

Re: Rietveld

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" by Armel le Bail :-)   Indeed, "never say never" is verified again. The powder

Re: Rietveld

I am an interested reader of this thread, but have no direct knowledge of any of the history. I will add, however, a small point about Alan’s last note suggesting we could go back to calling the process “Profile Refinement” and dodge the personal attribution. My point is that naming things

RE: Rietveld

t 2018 11:31 À : rietveld_l@ill.fr Objet : Re: Rietveld > ...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

Re: Rietveld

> ...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

Re: Rietveld

  >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.

Re: Rietveld

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 references Rietveld (1969) but uses a different type of profile refinement

Re: Rietveld

> * 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

Re: Rietveld list subscription

> > 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 >

RE: Rietveld refinement in TOPAS with parallel beam geometry

Patrick, From: Patrick Price [patrickpric...@gmail.com] Sent: Friday, December 04, 2009 6:30 AM To: Rietveld_l@ill.fr Subject: Rietveld refinement in TOPAS with parallel beam geometry Since this is my first post I will start with a brief introduction. My

Re: Rietveld refinement in TOPAS with parallel beam geometry

Sorry about the confusion on the instrument configuration. I am new to the field of x-ray diffraction. Hopefully this helps. The Bruker D8 uses reflection geometry and a THETA : THETA goniometer, where the x-ray source and detector can be move simultaneously on the arms of the goniometer. The

Re: Rietveld Neophyte

Dear Dave, Actually, GSAS is not the best choice for crystal size analysis. There are specialized programs for this purpose such as MAUD for instance. If you can’t refine the Gaussian broadening parameters GU GV and GW you may get them from the refinement for a standard with big (1000 nm)

Re: RE: Rietveld: U,V,W

synchrotron and neutron) can be found at http://mysite.du.edu/~balzar/s-s_rr.htm. Davor BalzarUniversity of Denverwww.du.eduwww.du.edu/~balzar - Original Message - From: Maxim V. Lobanov [EMAIL PROTECTED] Date: Sunday, November 30, 2008 10:37 pm Subject: RE: Rietveld: U,V,W

Re: Rietveld: U,V,W

Hi, Self Citation: NIST Standard Reference Materials for Characterization of Instrument Performance Industrial Applications of X-ray Diffraction Ed by F. H. Chung D. K. Smith, pp 903-917. A pdf is available; email to request. In this I outline how I use SRM 660 (it was 660 in 2000, then

Re: Rietveld: U,V,W

What is the correct procedure for refining U,V,W? It is my understanding that those parameters are a function of instrument geometry. Does one use a standard material to determine U,V,W and then fix their values for the instrument you're using?or do the values of U,V,W change

Re: Rietveld: U,V,W

Why my reply went to the author's personal mail box? I am very sorry for that. Now I am hunting for a standard reference material to determine the profile parameters of our instrument X'pert Pro. -- Mingtao Li State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and

RE: Rietveld: U,V,W

: Monday, December 01, 2008 5:21 AM To: May, Frank Cc: rietveld_l@ill.fr Subject: Re: Rietveld: U,V,W What is the correct procedure for refining U,V,W? It is my understanding that those parameters are a function of instrument geometry. Does one use a standard material to determine U,V,W and then fix

RE: Rietveld: U,V,W

Brian wrote: U and W should be instrumental constants that will not change with sample, while V can have both an instrumental and a residual stress component. Maxim wrote: as far as I understand, the strain broadening term should have FWMM~theta dependence, i.e. Lorentzian Y in standard (GSAS)

RE: Rietveld Round Robin Test

Title: Message There were two papers resulting from a round robin on quantitative phase analysis sponsored by the IUCr Commission on Powder Diffraction. They are:- (1) I.C. Madsen, N.V.Y. Scarlet, L.M.D. Cranswick, T. Lwin, J. Appl Cryst. (2001) 34, 409-426 (2) N.V.Y. Scarlet, I.C.

Re: rietveld refinement

Hi, At the moment there is development of a NIST Nanocrystallite Size Standard Reference Material (SRM1979). Jim Cline and I are working on this SRM. It will include two materials: (1) CeO2 with spherical crystallite shape and size distribution in the ~20nm size range (isotropic shape); (2) ZnO

Re: rietveld refinement

just my 2 cents... Could I be so stupid to say that such kind of works, including mine, are nothing? following Nicolae, I should also add to the list myself as well as most people participating to the four editions of the size-strain conference/meeting/workshop and all participants to

Re: rietveld refinement

So I cannot let say that Significantly different physical size distributions could describe equally well the peak profile. This is confusing. You may say that : significantly different crystallite shapes could describe equally well the peak profile in cubic symmetry. I am not sure that this

Re: rietveld refinement

Title: RE: rietveld refinement Doesn't help with a size distribution, as it only works well for a relatively monodisperse material - but it does work under some circumstances. Pam I disagree, it works also for large dispersion. One example you can find in JAC (2002) 35, 338

Re: rietveld refinement

It is also true that no development has been done for anisotropy. Not yet! Well, if all previous works about trying to take account of size/strain anisotropy in the Rietveld method are nothing yet, this allows to close the discussion. Let us wait for really serious developments to come. Armel

Re: rietveld refinement

Title: RE: rietveld refinement I'm afraid that you got the wrong end of the stick -I wasn't talking about the application of peak broadening to size distribution, I was commenting that determining crystallite shape is perfectly possible (some comments were flying that said otherwise

RE: rietveld refinement

can you please send me the soft copy of the paper you referred to. We don't have access to that journal... very much sincerely yours venkat From: Armel Le Bail [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Fri, 19

Re: rietveld refinement

can anyone send me a soft copy of the following paper J. Appl. Cryst. (1978). 11, 50-55. thanks venkat +++ M Venkata Kamalakar Junior Research Fellow, S.N.Bose.National Centre for Basic Sciences, Block-JD, Sector-3, Salt Lake, Kolkata, Pin:

Re: rietveld refinement

methodology, if not that they are physical (I believe they are physical in case of size-only effect). The diffraction alone can not decide. Significantly different physical size distributions could describe equally well the peak profile (J.Appl.Cryst. v35 (2002) 338-346 - self citation too).

Re: rietveld refinement

The diffraction alone can not decide. Significantly different physical size distributions could describe equally well the peak profile (J.Appl.Cryst. v35 (2002) 338-346 - self citation too). Nicolae Popa Looking at your figures 6b1 and 6b2, I measure how we differ on the sense of significantly

Re: rietveld refinement

The diffraction alone can not decide. Significantly different physical size distributions could describe equally well the peak profile (J.Appl.Cryst. v35 (2002) 338-346 - self citation too). Nicolae Popa Looking at your figures 6b1 and 6b2, I measure how we differ on the sense of

Re: rietveld refinement

What we see in diffraction is the column lengths (volume area averaged) and the classics were not full ignoring the shape and radius (radii) distribution(s). Nicolae Popa (Mister, Messieur, Don, Dom, etc.) Of course I agree with you that completely different shapes may correspond to the same

Re: rietveld refinement

Small error, sorry, three of the possible arrangement were : |--| | |--| | | |--|--| |--|--|--|--| |--| | | |--| | |--|--| | |--|--|--|--| |--| | | |--| | | | | |--| |--| |--| |--|

RE: rietveld refinement

Hi Venkat, If you mean to use rietveld on X-ray data I don't think you can get particle size distributions. X=ray data will give you an average crystallite size but this is not a distribution just an average. Also, it is crystallite size and the actual particles size can be different if the

Re: rietveld refinement

This is where the real fun starts (if you're a masochist!). I just finished doing some work along those lines this afternoon, and managed to get it to work(ish) eventually. The double-Voigt analysis can give you Dv (volume weighted domain size) and Ds (surface weighted domain size). If you

RE: Rietveld refinement and PDF refinement ?

do you really have the resolution even on HRPD to see the diffuse scattering between Bragg peaks at high Q ? No we don't, but this is not the main point (by the way, we don't use HRPD for PDF, it doesn't go to sufficiently short wavelengths). The main reason to go to high Q is to avoid

RE: Rietveld refinement and PDF refinement ?

Another reason which may preclude your self-convincing is the fact that all the very good PDF studies of materials... are not by using constant wavelength neutrons... You are right Armel :-) About the current advantage of SR and TOF for PDF, I mean. That is why I am interested in being

RE: Rietveld refinement and PDF refinement ?

Adding 2 cents to the discussion... But I will try to convince myself otherwise :-) Another reason which may preclude your self-convincing is the fact that all the very good PDF studies of materials that are not perfectly crystallized (producing diffuse scattering), though not being amorphous, are

Re: Rietveld refinement and PDF refinement ?

Well, that is an old chestnut that Cooper and Rollet used to oppose to Rietveld refinement. I think Rollet eventually agreed that Rietveld was the better method. Has Bill really gone back on that ? The difference between the two approaches are just an interchange of the order of summations

RE: Rietveld refinement and PDF refinement ?

I would argue that the Bragg diffuse scattering both reflect the average instantaneous atomic structure. Yes. If you integrate over energy, the scattering function factors to a delta function in time, corresponding to an instantaneous snapshot of the spatial correlations. It is not a question

Re: Rietveld refinement and PDF refinement ?

Jon others, Well, there is an attempt at this in GSAS - the diffuse scattering functions for fitting these contributions separate from the background functions. These things have three forms related to the Debye equations formulated for glasses. The possibly neat thing about them is that they

RE: Rietveld refinement and PDF refinement ?

Two very good points by Armel: all the very good PDF studies ...are made by using synchrotron data or neutron data from spallation sources This is because they are the only means to get to high Q (i.e., high resolution in real space) and sufficiently high resolution (in reciprocal space)

RE: Rietveld refinement and PDF refinement ?

Two very good points by Armel: all the very good PDF studies ...are made by using synchrotron data or neutron data from spallation sources And he is modest as well :-) But do you really have the resolution even on HRPD to see the diffuse scattering between Bragg peaks at high Q ? You may get

Re: Rietveld refinement and PDF refinement ?

I'd only add that given the clue that the peak in GaInAs is split from the PDF then one should model it that way in a Rietveld refinement. It should agree. The thrown away info in a Rietveld refinement is also evident in the Bragg peak intensities - shows up as funny thermal parameters, low

RE: Rietveld refinement and PDF refinement ?

The only truly unique PDF information is about *correlations*. Let's say you have two bonded sites, both with anisotropic thermal ellipsoids along the bond, and let's assume that the motion is purely harmonic. A sharp PDF peak will indicate that the atoms move predominanly in-phase, a broad PDF

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