Re: [Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Carlo Segre]

Hi Ed:

You do not need to start with a CIF file at all.  All you need is the 
space group, the lattice constants and the atomic positions.  You can then 
fillin the blanks for the Atoms program yourself.


Carlo

On Mon, 8 Aug 2016, Ed Han wrote:


Hello All,

I apologize in advance if this is not the correct method to reply to the
thread.

Thank you for your replies and suggestions. I will look further into
determining the atomic structure of the Hf-Al intermetallics through their
papers.

Once I obtain this information, how do I go about creating the actual CIF
file? Can I just open up any arbitrary CIF file and then change the
parameters and name to match that of the Hf-Al systems?

Lastly, going through some CIF files from crystallography.net, I notice
that some of the 3D models from the CIF has a different stoichiometry from
the designated crystal. For example, I have attached a CIF file of SiO2
that I have found; however, the 3D representation only has 1 Silicon atom
and 1 Oxygen atom. Do you have any insight on this disparity?

Regards,
Ed Han



--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org
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Re: [Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Matthew Marcus]

Use ATOMS, which lets you define the structure by filling in a form, then save 
as an ATOMS .inp file.  You don't need the .cif.  I forget whether ATOMS
can save as .cif.

The crystallographic symmetry rules will duplicate the O atom for you.  The CIF 
only shows symmetry-inequivqlent atoms.
mam

On 8/8/2016 3:44 PM, Ed Han wrote:

Hello All,

I apologize in advance if this is not the correct method to reply to the thread.

Thank you for your replies and suggestions. I will look further into 
determining the atomic structure of the Hf-Al intermetallics through their 
papers.

Once I obtain this information, how do I go about creating the actual CIF file? 
Can I just open up any arbitrary CIF file and then change the parameters and 
name to match that of the Hf-Al systems?

Lastly, going through some CIF files from crystallography.net 
, I notice that some of the 3D models from the CIF 
has a different stoichiometry from the designated crystal. For example, I have 
attached a CIF file of SiO2 that I have found; however, the 3D representation only 
has 1 Silicon atom and 1 Oxygen atom. Do you have any insight on this disparity?

Regards,
Ed Han


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[Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Ed Han]

Hello All,

I apologize in advance if this is not the correct method to reply to the
thread.

Thank you for your replies and suggestions. I will look further into
determining the atomic structure of the Hf-Al intermetallics through their
papers.

Once I obtain this information, how do I go about creating the actual CIF
file? Can I just open up any arbitrary CIF file and then change the
parameters and name to match that of the Hf-Al systems?

Lastly, going through some CIF files from crystallography.net, I notice
that some of the 3D models from the CIF has a different stoichiometry from
the designated crystal. For example, I have attached a CIF file of SiO2
that I have found; however, the 3D representation only has 1 Silicon atom
and 1 Oxygen atom. Do you have any insight on this disparity?

Regards,
Ed Han


9000775.cif
Description: Binary data
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Re: [Ifeffit] Ti data problem

[Carlo Segre]

Hi Jia:

For the first one of the spectra, I chose the shoulder in the derivative 
at 4974 instead of the large peak.  I consider the lower energy peak to be 
a pre-edge feature due to the 3d quadrupole transitions and I generally 
don't choose that.  If the analysis later tells me that I am wrong, I move 
it accordingly.


In this case, the 4974 positoin withthe other parameters I mentioned gives 
a very reasonable FT.


Carlo

On Mon, 8 Aug 2016, Qingying Jia wrote:


Hi Carlo,

 In many transition metal oxide cases like this, what would be the more
proper E0, the position of the apex of the first derivative peak or the
second one that is usually higher than the first peak, or it really
depends? I have seen people using either. In this particular case, it seems
like using E0 of 4967 eV (the first derivative peak position) gives cleaner
and more reasonable FT-EXAFS.

 Regards,
 Jia

On Mon, Aug 8, 2016 at 5:05 PM, Carlo Segre  wrote:



Hi Siliang:

The first thing is that you have misidentified the edge position.  Itis
way too high in all the data sets.

Put it at the inflection point of the main rise in the absorption curve
and you will find that the problem is much reduced.

The second thing is that you have a very bad backgrund problem in your
data and, in my estimation your usable data range is no moe than k=2 to
k=8.  In fact, my suggestion is that you truncate the data by setting the
spline range to end at 8.  The FT range should probably be set at 2-8 or
even 2-7 (somewhere in that range and put a window sill of dk=2 to get rid
of some of the ringing.

Once you do those things the data will look much more reasonable.

These data could probably have used some longer counting times.  Where did
you take the data?

Carlo

On Mon, 8 Aug 2016, Siliang Chang wrote:

Dear all,




I am new to XAFS data analysis. I?m currently working on the XAFS data of
atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and
Ti
K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid
solution. However, Ti data really confuses me (please see attached file).
With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this
is something I have never seen in the literature. I?m wondering if this is
normal? Does this mean I should set a larger Rbkg value, say, around 1.5?



I?ve tried to fit the abovementioned Ti data using several models:
anatase,
rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of
those), so far no success. I would really appreciate if you can comment on
my data processing, any suggestions are welcomed, as I?m new to this, I?m
not sure if I?m doing it the right way.



Thank you very much.



Best regards,

Siliang Chang








--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org
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--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org___
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Re: [Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Matthew Marcus]

That's a theoretical paper, so I don't know how reliable those numbers are.  It 
will take Han some care with crystallography to translate the data into 
something
usable by Atoms, i.e. a complete site list.  I suggest starting with structures 
with the same code (e.g. D022) and filling in new parameters per that paper
or experimental ones.
mam

On 8/8/2016 2:15 PM, Bruce Ravel wrote:


Have you read the Colinet & Pasturel paper?  Skimming through it, it seems like 
section III.b along with Fig 1 gives enough information to fill in the Atoms window 
(http://bruceravel.github.io/demeter/documents/Artemis/feff/index.html) by hand.

B


On 08/08/2016 05:02 PM, Ed Han wrote:

Dear All,

In the upcoming fall, my research group plans on performing XAS studies
observing the Hf L3-edge for various Hf-Al intermetallic samples.

In preparation for the experiments, I am looking for CIF files of the
various Hf-Al intermetallic systems, including HfAl3, HfAl2, Hf4Al3, etc.

Upon scavenging through a multitude of crystallographic databases, I was
not able to find any CIF files of Hf-Al intermetallics. However, I have
acquired powder diffraction files (PDF) for said intermetallics.

Seeing as how PDFs cannot be used in Artemis for EXAFS data analysis (to
my knowledge), is there a way to convert PDFs into CIFs? I have attached
one of the PDF files to demonstrate what information it contains.

I would really appreciate your help!

Regards,
Edmund Han





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Re: [Ifeffit] Ti data problem

[Carlo Segre]

Your data is very noisy through the edge.  Longer acquisition times would 
help reduce the noise.


carlo

On Mon, 8 Aug 2016, Siliang Chang wrote:


Hi Carlo,

Thank you for the response. I will try what you mentioned here. The data is
taken at APS beamline 5BMD. May I ask what is the effect of longer counting
times?

Siliang

-Original Message-
From: Carlo Segre [mailto:se...@iit.edu]
Sent: Monday, August 08, 2016 4:05 PM
To: Siliang Chang 
Cc: ifeffit@millenia.cars.aps.anl.gov
Subject: Re: [Ifeffit] Ti data problem


Hi Siliang:

The first thing is that you have misidentified the edge position.  Itis way
too high in all the data sets.

Put it at the inflection point of the main rise in the absorption curve and
you will find that the problem is much reduced.

The second thing is that you have a very bad backgrund problem in your data
and, in my estimation your usable data range is no moe than k=2 to k=8.  In
fact, my suggestion is that you truncate the data by setting the spline
range to end at 8.  The FT range should probably be set at 2-8 or even 2-7
(somewhere in that range and put a window sill of dk=2 to get rid of some of
the ringing.

Once you do those things the data will look much more reasonable.

These data could probably have used some longer counting times.  Where did
you take the data?

Carlo

On Mon, 8 Aug 2016, Siliang Chang wrote:


Dear all,



I am new to XAFS data analysis. I?m currently working on the XAFS data
of atomic layer deposited mixed oxide thin film: SnTiOx. I have both
Sn and Ti K edge data, and was able to fit Sn edge using a model of
(Sn,Ti)O2 solid solution. However, Ti data really confuses me (please see

attached file).

With Rbkg set to 1, there is a doublet in 1-2 Å region in every data,
this is something I have never seen in the literature. I?m wondering
if this is normal? Does this mean I should set a larger Rbkg value, say,

around 1.5?




I?ve tried to fit the abovementioned Ti data using several models:
anatase, rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6
for all of those), so far no success. I would really appreciate if you
can comment on my data processing, any suggestions are welcomed, as
I?m new to this, I?m not sure if I?m doing it the right way.



Thank you very much.



Best regards,

Siliang Chang








--
Carlo U. Segre -- Duchossois Leadership Professor of Physics Interim Chair,
Department of Chemistry Director, Center for Synchrotron Radiation Research
and Instrumentation Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org




--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org___
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Re: [Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Matthew Marcus]

I'm afraid a PDF file of that sort is useless for EXAFS work because it doesn't 
tell you where the atoms are.  It only tells you the size of the unit cell,
unless you use it to solve the crystal structure yourself, which I don't 
recommend :-)  You need to search the literature for structures which include
the atomic positions and, probably, transcribe them manually into Atoms.  The 
paper referred to in the PDF gives calculated (not experimental) values
for the atomic displacements, from which, with some care, it would be possible 
to figure out coordinates.  However, it would be better to have experimental
data.  A bit of Googling shows that it's not going to be trivial to get all the 
parameters because the papers tend to tell you that the structures are
like other structures, but with certain parameters different, and you'll have 
to fill in the blanks.
mam


On 8/8/2016 2:02 PM, Ed Han wrote:

Dear All,

In the upcoming fall, my research group plans on performing XAS studies 
observing the Hf L3-edge for various Hf-Al intermetallic samples.

In preparation for the experiments, I am looking for CIF files of the various 
Hf-Al intermetallic systems, including HfAl3, HfAl2, Hf4Al3, etc.

Upon scavenging through a multitude of crystallographic databases, I was not 
able to find any CIF files of Hf-Al intermetallics. However, I have acquired 
powder diffraction files (PDF) for said intermetallics.

Seeing as how PDFs cannot be used in Artemis for EXAFS data analysis (to my 
knowledge), is there a way to convert PDFs into CIFs? I have attached one of 
the PDF files to demonstrate what information it contains.

I would really appreciate your help!

Regards,
Edmund Han





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Re: [Ifeffit] Ti data problem

[Qingying Jia]

Hi Carlo,

  In many transition metal oxide cases like this, what would be the more
proper E0, the position of the apex of the first derivative peak or the
second one that is usually higher than the first peak, or it really
depends? I have seen people using either. In this particular case, it seems
like using E0 of 4967 eV (the first derivative peak position) gives cleaner
and more reasonable FT-EXAFS.

  Regards,
  Jia

On Mon, Aug 8, 2016 at 5:05 PM, Carlo Segre  wrote:

>
> Hi Siliang:
>
> The first thing is that you have misidentified the edge position.  Itis
> way too high in all the data sets.
>
> Put it at the inflection point of the main rise in the absorption curve
> and you will find that the problem is much reduced.
>
> The second thing is that you have a very bad backgrund problem in your
> data and, in my estimation your usable data range is no moe than k=2 to
> k=8.  In fact, my suggestion is that you truncate the data by setting the
> spline range to end at 8.  The FT range should probably be set at 2-8 or
> even 2-7 (somewhere in that range and put a window sill of dk=2 to get rid
> of some of the ringing.
>
> Once you do those things the data will look much more reasonable.
>
> These data could probably have used some longer counting times.  Where did
> you take the data?
>
> Carlo
>
> On Mon, 8 Aug 2016, Siliang Chang wrote:
>
> Dear all,
>>
>>
>>
>> I am new to XAFS data analysis. I?m currently working on the XAFS data of
>> atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and
>> Ti
>> K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid
>> solution. However, Ti data really confuses me (please see attached file).
>> With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this
>> is something I have never seen in the literature. I?m wondering if this is
>> normal? Does this mean I should set a larger Rbkg value, say, around 1.5?
>>
>>
>>
>> I?ve tried to fit the abovementioned Ti data using several models:
>> anatase,
>> rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of
>> those), so far no success. I would really appreciate if you can comment on
>> my data processing, any suggestions are welcomed, as I?m new to this, I?m
>> not sure if I?m doing it the right way.
>>
>>
>>
>> Thank you very much.
>>
>>
>>
>> Best regards,
>>
>> Siliang Chang
>>
>>
>>
>>
>>
>>
>>
> --
> Carlo U. Segre -- Duchossois Leadership Professor of Physics
> Interim Chair, Department of Chemistry
> Director, Center for Synchrotron Radiation Research and Instrumentation
> Illinois Institute of Technology
> Voice: 312.567.3498Fax: 312.567.3494
> se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org
> ___
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Re: [Ifeffit] Ti data problem

[Siliang Chang]

Hi Carlo,

Thank you for the response. I will try what you mentioned here. The data is
taken at APS beamline 5BMD. May I ask what is the effect of longer counting
times?

Siliang

-Original Message-
From: Carlo Segre [mailto:se...@iit.edu] 
Sent: Monday, August 08, 2016 4:05 PM
To: Siliang Chang 
Cc: ifeffit@millenia.cars.aps.anl.gov
Subject: Re: [Ifeffit] Ti data problem


Hi Siliang:

The first thing is that you have misidentified the edge position.  Itis way
too high in all the data sets.

Put it at the inflection point of the main rise in the absorption curve and
you will find that the problem is much reduced.

The second thing is that you have a very bad backgrund problem in your data
and, in my estimation your usable data range is no moe than k=2 to k=8.  In
fact, my suggestion is that you truncate the data by setting the spline
range to end at 8.  The FT range should probably be set at 2-8 or even 2-7
(somewhere in that range and put a window sill of dk=2 to get rid of some of
the ringing.

Once you do those things the data will look much more reasonable.

These data could probably have used some longer counting times.  Where did
you take the data?

Carlo

On Mon, 8 Aug 2016, Siliang Chang wrote:

> Dear all,
>
>
>
> I am new to XAFS data analysis. I?m currently working on the XAFS data 
> of atomic layer deposited mixed oxide thin film: SnTiOx. I have both 
> Sn and Ti K edge data, and was able to fit Sn edge using a model of 
> (Sn,Ti)O2 solid solution. However, Ti data really confuses me (please see
attached file).
> With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, 
> this is something I have never seen in the literature. I?m wondering 
> if this is normal? Does this mean I should set a larger Rbkg value, say,
around 1.5?
>
>
>
> I?ve tried to fit the abovementioned Ti data using several models: 
> anatase, rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 
> for all of those), so far no success. I would really appreciate if you 
> can comment on my data processing, any suggestions are welcomed, as 
> I?m new to this, I?m not sure if I?m doing it the right way.
>
>
>
> Thank you very much.
>
>
>
> Best regards,
>
> Siliang Chang
>
>
>
>
>
>

--
Carlo U. Segre -- Duchossois Leadership Professor of Physics Interim Chair,
Department of Chemistry Director, Center for Synchrotron Radiation Research
and Instrumentation Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
se...@iit.edu   http://phys.iit.edu/~segre   se...@debian.org


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Re: [Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Bruce Ravel]

Have you read the Colinet & Pasturel paper?  Skimming through it, it 
seems like section III.b along with Fig 1 gives enough information to 
fill in the Atoms window 
(http://bruceravel.github.io/demeter/documents/Artemis/feff/index.html) 
by hand.


B


On 08/08/2016 05:02 PM, Ed Han wrote:

Dear All,

In the upcoming fall, my research group plans on performing XAS studies
observing the Hf L3-edge for various Hf-Al intermetallic samples.

In preparation for the experiments, I am looking for CIF files of the
various Hf-Al intermetallic systems, including HfAl3, HfAl2, Hf4Al3, etc.

Upon scavenging through a multitude of crystallographic databases, I was
not able to find any CIF files of Hf-Al intermetallics. However, I have
acquired powder diffraction files (PDF) for said intermetallics.

Seeing as how PDFs cannot be used in Artemis for EXAFS data analysis (to
my knowledge), is there a way to convert PDFs into CIFs? I have attached
one of the PDF files to demonstrate what information it contains.

I would really appreciate your help!

Regards,
Edmund Han





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--
 Bruce Ravel   bra...@bnl.gov

 National Institute of Standards and Technology
 Synchrotron Science Group at NSLS-II
 Building 743, Room 114
 Upton NY, 11973

 Homepage:http://bruceravel.github.io/home/
 Software:https://github.com/bruceravel
 Demeter: http://bruceravel.github.io/demeter/
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[Ifeffit] Converting PDF files to CIF files for usage in Artemis

[Ed Han]

Dear All,

In the upcoming fall, my research group plans on performing XAS studies
observing the Hf L3-edge for various Hf-Al intermetallic samples.

In preparation for the experiments, I am looking for CIF files of the
various Hf-Al intermetallic systems, including HfAl3, HfAl2, Hf4Al3, etc.

Upon scavenging through a multitude of crystallographic databases, I was
not able to find any CIF files of Hf-Al intermetallics. However, I have
acquired powder diffraction files (PDF) for said intermetallics.

Seeing as how PDFs cannot be used in Artemis for EXAFS data analysis (to my
knowledge), is there a way to convert PDFs into CIFs? I have attached one
of the PDF files to demonstrate what information it contains.

I would really appreciate your help!

Regards,
Edmund Han
PDF#97-024-8537: QM=Calculated; d=Calculated; I=(Unknown)
Hafnium Aluminide (1/3)
HfAl3   
Radiation=CuKa1 Lambda=1.5406   Filter=
Calibration=2T=21.706-89.581I/Ic(RIR)=8.84
Ref: Calculated from FIZ#248537 (09/22/15) by Jade

Cubic, Pm-3m (221)  Z=1
CELL: 4.091 x 4.091 x 4.091 <90.0 x 90.0 x 90.0>P.S=
Density(c)=6.292Density(m)= Mwt=Vol=68.5
Ref: Ibid.

Strong Lines: 2.36/X 4.09/X 2.89/8 2.05/5 1.83/4 1.23/3 1.45/3 1.67/3
NOTE: FIZ#248537: "Phase stability and electronic structure of the HfAl3 
compound", Colinet, C.;Pasturel, A., Physical Review, Serie 3.
B - Condensed Matter (18,1978-), v64 (2001) 205102-1-205102-11, Electron 
structure calculation.
Standard deviation missing in cell constants.
Structure calculated theoretically.
Structure type : Auricupride-AuCu3.
No R value given in the paper.
At least one temperature factor missing in the paper.

2-Thetad(Å)   I(f)  ( h k l)   Theta  1/(2d)   2pi/d  n^2  
 21.706  4.0910   95.4  ( 1 0 0)  10.853  0.1222  1.53591
 30.886  2.8928   78.6  ( 1 1 0)  15.443  0.1728  2.17202
 38.068  2.3619  100.0  ( 1 1 1)  19.034  0.2117  2.66023
 44.244  2.0455   48.0  ( 2 0 0)  22.122  0.2444  3.07174
 49.799  1.8296   39.4  ( 2 1 0)  24.900  0.2733  3.43435
 54.931  1.6701   28.7  ( 2 1 1)  27.466  0.2994  3.76216
 64.358  1.4464   29.0  ( 2 2 0)  32.179  0.3457  4.34418
 68.787  1.3637   17.3  ( 2 2 1)  34.393  0.3667  4.60769
 73.086  1.2937   11.5  ( 3 1 0)  36.543  0.3865  4.8568   10
 77.289  1.2335   32.5  ( 3 1 1)  38.645  0.4054  5.0939   11
 81.424  1.18109.4  ( 2 2 2)  40.712  0.4234  5.3204   12
 85.514  1.13467.4  ( 3 2 0)  42.757  0.4407  5.5376   13
 89.581  1.0934   13.4  ( 3 2 1)  44.791  0.4573  5.7466   14
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Re: [Ifeffit] Ti data problem

[Carlo Segre]

Hi Siliang:

The first thing is that you have misidentified the edge position.  Itis 
way too high in all the data sets.


Put it at the inflection point of the main rise in the absorption curve 
and you will find that the problem is much reduced.


The second thing is that you have a very bad backgrund problem in your 
data and, in my estimation your usable data range is no moe than k=2 to 
k=8.  In fact, my suggestion is that you truncate the data by setting the 
spline range to end at 8.  The FT range should probably be set at 2-8 or 
even 2-7 (somewhere in that range and put a window sill of dk=2 to get rid 
of some of the ringing.


Once you do those things the data will look much more reasonable.

These data could probably have used some longer counting times.  Where did 
you take the data?


Carlo

On Mon, 8 Aug 2016, Siliang Chang wrote:


Dear all,



I am new to XAFS data analysis. I?m currently working on the XAFS data of
atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and Ti
K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid
solution. However, Ti data really confuses me (please see attached file).
With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this
is something I have never seen in the literature. I?m wondering if this is
normal? Does this mean I should set a larger Rbkg value, say, around 1.5?



I?ve tried to fit the abovementioned Ti data using several models: anatase,
rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of
those), so far no success. I would really appreciate if you can comment on
my data processing, any suggestions are welcomed, as I?m new to this, I?m
not sure if I?m doing it the right way.



Thank you very much.



Best regards,

Siliang Chang








--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498Fax: 312.567.3494
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[Ifeffit] Ti data problem

[Siliang Chang]

Dear all,

 

I am new to XAFS data analysis. I’m currently working on the XAFS data of
atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and Ti
K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid
solution. However, Ti data really confuses me (please see attached file).
With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this
is something I have never seen in the literature. I’m wondering if this is
normal? Does this mean I should set a larger Rbkg value, say, around 1.5?

 

I’ve tried to fit the abovementioned Ti data using several models: anatase,
rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of
those), so far no success. I would really appreciate if you can comment on
my data processing, any suggestions are welcomed, as I’m new to this, I’m
not sure if I’m doing it the right way.

 

Thank you very much.

 

Best regards,

Siliang Chang

 

 



Ti_K_edge2.prj
Description: Binary data
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Re: [Ifeffit] Amorphous

[Bruce Ravel]

On 08/08/2016 11:19 AM, Carlos Triana Estupinan wrote:

I want to know if it is possible to obtain a 3D structure (.cif file) of
an amorphous material from the EXAFS fitting carried out from artemis. I
mean, there is a way to extract a .cif file with the structural data
obtained from the refined spectra.


No.

EXAFS is basically a one-dimensional measurement.  You measure R. 
Multiple scattering gives you limited information about the 3D 
arrangement of atoms, but mostly EXAFS is just R.


Unless I am misunderstanding the question, I don't think you can do what 
you are asking even for a well-ordered crystal, much less an amorphous 
material.



Also, in amorphous materials there
must be a distribution of interatomic bond distances and coordination,
and so, how can I address such a structural distribitions.


Well, sure.

There is a while literature on the use X-ray or neutron scattering along 
with EXAFS and molecular dynamics and monte carlo methods to study 
amorphous materials.  It seems that the most successful approaches 
involve forward modeling -- i.e. testing structures against the EXAFS data.


There simply isn't enough information in EXAFS to invert the EXAFS and 
extract a 3d configuration.  Artemis does not even try to do that.


B


--
 Bruce Ravel   bra...@bnl.gov

 National Institute of Standards and Technology
 Synchrotron Science Group at NSLS-II
 Building 743, Room 114
 Upton NY, 11973

 Homepage:http://bruceravel.github.io/home/
 Software:https://github.com/bruceravel
 Demeter: http://bruceravel.github.io/demeter/
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[Ifeffit] Amorphous

[Carlos Triana Estupinan]

Dear
Bruce

I want to know if it is possible to obtain a 3D structure (.cif file) of an
amorphous material from the EXAFS fitting carried out from artemis. I mean,
there is a way to extract a .cif file with the structural data obtained
from the refined spectra. Also, in amorphous materials there must be a
distribution of interatomic bond distances and coordination, and so, how
can I address such a structural distribitions.

Regards.
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