RE: Mixed refinement Topas example

[Cline, James Dr. (Fed)]

François,

Somewhat more than slightly curious: Why do you want to use Topas in GUI mode?

Jim


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

-Original Message-
From: rietveld_l-requ...@ill.fr  On Behalf Of Luzia 
Germann
Sent: Friday, November 02, 2018 9:17 AM
To: rietveld_l@ill.fr
Subject: Re: Mixed refinement Topas example

Hey François,

You can find an example (with input file) on John's wonderful webpage under the 
following page:

https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcommunity.dur.ac.uk%2Fjohn.evans%2Ftopas_workshop%2Ftutorial_combined.htm&data=02%7C01%7Cjames.cline%40nist.gov%7Cb56878acaf134a6fdd5a08d640c58634%7C2ab5d82fd8fa4797a93e054655c61dec%7C1%7C0%7C636767614451670425&sdata=Yhn2S6ldVw2lvbtDMOTT%2Fza6gjO0I73iBncJDpdM1tw%3D&reserved=0

There are also other, really cool tutorials, worth checking out!

Best,
Luzia

Quoting François Goutenoire :

> Dear Rietveld users,
>
> I am starting with Topas5.0 commercial, and I would like to do a mixed 
> X-Ray-Neutron refinement directly on GUI mode.
>
> Does anyone can send me an example of *.PRO file or even an *.INP file 
> to to the refinement in launch mode.
>
> The neutron data are with constant wavelength.
>
> Thanks in advance.
>
> --
> **
> ***
> 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 2019
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> ormation.cnrs.fr%2Fstage.php%3Fstage%3D19089&data=02%7C01%7Cjames.
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> a93e054655c61dec%7C1%7C0%7C636767614451670425&sdata=aYdg0gg%2FhTWw
> hBPMBfn9u5lmxXKDwNh70ZDih8OOMNk%3D&reserved=0
> Formation SAXS et Réflectivités pour couches minces et matériaux 
> nanostructurés.
> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcnrsf
> ormation.cnrs.fr%2Fstage.php%3Fstage%3D19093&data=02%7C01%7Cjames.
> cline%40nist.gov%7Cb56878acaf134a6fdd5a08d640c58634%7C2ab5d82fd8fa4797
> a93e054655c61dec%7C1%7C0%7C636767614451670425&sdata=99Myif%2B0dBbc
> r1r8Plgg4y163Ma8RhxdKeE0nwbCl6k%3D&reserved=0
> Bibliographie
> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fschol
> ar.google.fr%2Fcitations%3Fhl%3Dfr%26user%3DqC-lmN4J%26view_op%3Dl
> ist_works%26authuser%3D1%26sortby%3Dtitle&data=02%7C01%7Cjames.cli
> ne%40nist.gov%7Cb56878acaf134a6fdd5a08d640c58634%7C2ab5d82fd8fa4797a93
> e054655c61dec%7C1%7C0%7C636767614451670425&sdata=mjclfF1FR4s57RbKD
> Wxo44qGjopbhhQodIFwaFBP8jc%3D&reserved=0
> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Forcid
> .org%2F-0001-5339-3002&data=02%7C01%7Cjames.cline%40nist.gov%7
> Cb56878acaf134a6fdd5a08d640c58634%7C2ab5d82fd8fa4797a93e054655c61dec%7
> C1%7C0%7C636767614451670425&sdata=QNZFU9f7yP419SlmuOagzo18rGclVUVv
> dxeSExIH5A0%3D&reserved=0
>
>
>
> ---
> L'absence de virus dans ce courrier électronique a été vérifiée par le 
> logiciel antivirus Avast.
> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.a
> vast.com%2Fantivirus&data=02%7C01%7Cjames.cline%40nist.gov%7Cb5687
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> %7C636767614451670425&sdata=bepY%2FppDj96pLQ8j1swH8o2S%2BtyysqDg0O
> XEdCwVw2k%3D&reserved=0



--
Luzia S. Germann
Scientific Service Group Diffraction
Max-Planck-Institute for Solid State Research Heisenbergstr. 1
70569 Stuttgart
Germany

Phone: +49 711 689-1506

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Cu K alpha Spectrum

[Cline, James Dr. (Fed)]

Hi all,

We now have a paper concerning the NIST opinion as to the nature of the Cu K* 
emission spectrum.  Please see:

http://iopscience.iop.org/article/10.1088/1361-6455/aa6c4a/meta;jsessionid=0F01A1609C56F9C09F01B4DBA2B997A8.ip-10-40-1-105

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
james.cl...@nist.gov
(301) 975 5793

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RE: using Zero

[Cline, James Dr. (Fed)]

Johannes,

I’m somewhat confounded as to what your difficulty is with this sample 
displacement function?

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<mailto: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 
Johannes Birkenstock
Sent: Thursday, March 30, 2017 4:23 AM
To: rietveld_l@ill.fr
Subject: Re: using Zero


Hi to all,

@Leopoldo, thank you for providing the nice listing of the most relevant 
quantities determining the reflections' positions.
However, I think there is a minor mistake in the description for the sample 
displacement: The given relation (-s·cos(theta) or in full -2s·cos(theta)/R 
with R = goniometer radius, e.g. Klug, Alexander 1974) implies that it is 0 at 
180°2Theta, i.e., it continuously decreases with growing 2Theta. This also 
seems to be intuitive when you prepare a small sketch on how a misplaced sample 
height affects a reflection's position at low, moderate and high diffraction 
angles.

Best regards from Bremen,
Johannes

Am 29.03.2017 um 15:54 schrieb Cline, James Dr. (Fed):
Hi,

Seems everyone has beaten on this matter quite well.  I humbly offer this 
paper: http://nvlpubs.nist.gov/nistpubs/jres/120/jres.120.013.pdf
which discusses how you can experimentally determine (eliminate) the zero error 
with considerable certainly.

You should consider what you know the most, and least, about: you can never 
know the sample displacement or attenuation errors, you might know the lattice 
parameters, and you can eliminate the zero error if you want to.  You can 
refine all parameters with high angle data; but you must be careful to inspect 
results for loss of physical plausibility.  I do this only as an adventurous 
exercise.

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
james.cl...@nist.gov<mailto:james.cl...@nist.gov>
(301) 975 5793

From: rietveld_l-requ...@ill.fr<mailto:rietveld_l-requ...@ill.fr> 
[mailto:rietveld_l-requ...@ill.fr] On Behalf Of David L. Bish
Sent: Wednesday, March 29, 2017 9:41 AM
To: rietveld_l@ill.fr<mailto:rietveld_l@ill.fr>
Subject: Re: using Zero


Hi Ana Isabel,

Following up on Stan's comments, we always perform this type of calibration 
with a certified standard, e.g., an NIST standard (Si or LaB6). We then measure 
data from below the lowest-angle peak up the high-angle limit of the instrument 
(about 155 deg. in our case). If you use a certified standard, you can FIX the 
unit-cell parameter(s) and refine zero error and specimen displacement 
corrections. I typically obtain good refinements, with small esd's, when I 
follow this procedure. After all, the purpose is not to obtain the unit-cell 
parameter of your standard. If you have the ability to adjust the zero error of 
your instrument, you can then do that after doing your refinements. Ultimately 
you should be able to achieve a very small zero error.

Make sure you then use that refined zero error in subsequent refinements, until 
you realign your instrument. The zero error should not be a function of your 
sample. Specimen displacement is a function of each sample (mount) and should 
always be refined to obtain more accurate (not precise) unit-cell parameters.

Cheers,

Dave

On 3/29/2017 9:23 AM, Leopoldo Suescun wrote:
Hola Ana Isabel,

As Stan said, if you go high enough in 2theta you have enough data to 
de-correlate zero and sample displacement corrections and you can refine them 
together with lattice parameters, and have correct values for the three.

The reason for thi si that delta(2theta) for each peak is a fixed amount with 
zero (for all 2theta), proportional to -Scos(theta) with S sample displacement 
and proportional to arcsin(lambda/2d) with change of lattice parameters.

Since these three terms affecting peak positions have different behaviors with 
2theta, zero is constant, displacement is maximum at low and high 2theta but 
null at 90 and lattice parameter increases the shift with 2theta (as does the 
separation of Kalfa1 and Kalfa2 peaks) then with a wide-enough patterns you 
will see the effects of the three affecting differently the low, mid and high 
2theta peaks, making a refinement possible.

But again, you need to go very high in 2theta to be able to de-correlate the 
three effects, collecting data from 10 to 80 degrees won´t allow you to refine 
more than one of the three with confidence (assuming the two you fix are 
correct).

Of course, aligning your diffractometer correctly and placing the sample at the 
place where it should be is always the best choice...

Good luck with your work
Leo

2017-03-29 8:38 GMT-03:00 Julian 

RE: using Zero

[Cline, James Dr. (Fed)]

Hi,

Seems everyone has beaten on this matter quite well.  I humbly offer this 
paper: http://nvlpubs.nist.gov/nistpubs/jres/120/jres.120.013.pdf
which discusses how you can experimentally determine (eliminate) the zero error 
with considerable certainly.

You should consider what you know the most, and least, about: you can never 
know the sample displacement or attenuation errors, you might know the lattice 
parameters, and you can eliminate the zero error if you want to.  You can 
refine all parameters with high angle data; but you must be careful to inspect 
results for loss of physical plausibility.  I do this only as an adventurous 
exercise.

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
james.cl...@nist.gov
(301) 975 5793

From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of 
David L. Bish
Sent: Wednesday, March 29, 2017 9:41 AM
To: rietveld_l@ill.fr
Subject: Re: using Zero


Hi Ana Isabel,

Following up on Stan's comments, we always perform this type of calibration 
with a certified standard, e.g., an NIST standard (Si or LaB6). We then measure 
data from below the lowest-angle peak up the high-angle limit of the instrument 
(about 155 deg. in our case). If you use a certified standard, you can FIX the 
unit-cell parameter(s) and refine zero error and specimen displacement 
corrections. I typically obtain good refinements, with small esd's, when I 
follow this procedure. After all, the purpose is not to obtain the unit-cell 
parameter of your standard. If you have the ability to adjust the zero error of 
your instrument, you can then do that after doing your refinements. Ultimately 
you should be able to achieve a very small zero error.

Make sure you then use that refined zero error in subsequent refinements, until 
you realign your instrument. The zero error should not be a function of your 
sample. Specimen displacement is a function of each sample (mount) and should 
always be refined to obtain more accurate (not precise) unit-cell parameters.

Cheers,

Dave

On 3/29/2017 9:23 AM, Leopoldo Suescun wrote:
Hola Ana Isabel,

As Stan said, if you go high enough in 2theta you have enough data to 
de-correlate zero and sample displacement corrections and you can refine them 
together with lattice parameters, and have correct values for the three.

The reason for thi si that delta(2theta) for each peak is a fixed amount with 
zero (for all 2theta), proportional to -Scos(theta) with S sample displacement 
and proportional to arcsin(lambda/2d) with change of lattice parameters.

Since these three terms affecting peak positions have different behaviors with 
2theta, zero is constant, displacement is maximum at low and high 2theta but 
null at 90 and lattice parameter increases the shift with 2theta (as does the 
separation of Kalfa1 and Kalfa2 peaks) then with a wide-enough patterns you 
will see the effects of the three affecting differently the low, mid and high 
2theta peaks, making a refinement possible.

But again, you need to go very high in 2theta to be able to de-correlate the 
three effects, collecting data from 10 to 80 degrees won´t allow you to refine 
more than one of the three with confidence (assuming the two you fix are 
correct).

Of course, aligning your diffractometer correctly and placing the sample at the 
place where it should be is always the best choice...

Good luck with your work
Leo

2017-03-29 8:38 GMT-03:00 Julian Richard Tolchard 
mailto:julianrichard.tolch...@sintef.no>>:
I would also suggest that it is easier to just check that your instrument zero 
is aligned than to mess around with long scans and fitting routines to separate 
correlated variables.


Jools


-Original Message-
From: rietveld_l-requ...@ill.fr 
[mailto:rietveld_l-requ...@ill.fr] On Behalf 
Of "Lukasz Kruszewski"
Sent: 29. mars 2017 13:25
To: Ana Isabel Becerro Nieto mailto:ani...@icmse.csic.es>>
Cc: rietveld_l@ill.fr
Subject: Re: using Zero

Hi. You can do that, of course, but you have to choose: you can use Zero error 
OR sample displacement, but never use both (this induces some physical 
impossibilities). However, I assume your diffractometer is calibrated, and the 
zero position of the detector is fine; the sample displacement may (I suppose) 
be connected with preparation-derived errors, and I'd use the latter parameter 
instead of the zero error.

Hope this helps anyhow. Good luck!

Luke Kruszewski


> Dear all,
>
> I am using Si as internal standard to calibrate my pattern. Should I
> refine the "Zero error" of the diffractometer if I am using the
> calibrated pattern?
>
> Thanks a lot,
>
> Ana
>
>
>
> Dra. Ana Isabel Becerro
>
> Instituto de Ciencia de Materiales de Sevilla
>
> CSIC-US
>
>
>
>

RE: order of Spherical Harmonics for correction of PO

[Cline, James Dr. (Fed)]

OK, can you list the citations for the papers in question?

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 
Laufek František
Sent: Tuesday, January 17, 2017 8:30 AM
To: 'Sitepu, Husinsyah' 
Cc: rietveld_l@ill.fr
Subject: RE: order of Spherical Harmonics for correction of PO

Dear Husin,

Thank you very much for the papers!

Best Regards,
Frantisek



From: Sitepu, Husinsyah [mailto:husinsyah.sit...@aramco.com]
Sent: Tuesday, January 17, 2017 6:37 AM
To: František Laufek
Subject: RE: order of Spherical Harmonics for correction of PO

Classification: Non-Business Use
Dear Dr Laufek,

The enclosed articles are probably useful information to answer your question.

All the best for the New Year.

Husin


Husin Sitepu, PhD
Saudi Aramco
Research and Development Center (R&DC)
Technical Service Division (TSD)
Advanced Analysis Unit (AAU)
Room: GB-110, Bld. 2296
P.O. Box 62, Dhahran 31311, Saudi Arabia
Phone: (966) 13 876 3050
Email: sitep...@aramco.com
Links at Google 
Scholar
 ResearchGate
[cid:image002.png@01D21A31.2CFC5620]



This email has been classified as Non-Business Use by Sitepu, Husinsyah on 
Tuesday, January 17, 2017 8:37:00 AM

From: rietveld_l-requ...@ill.fr 
[mailto:rietveld_l-requ...@ill.fr] On Behalf Of František Laufek
Sent: Monday, January 16, 2017 12:11 AM
To: rietveld_l@ill.fr
Subject: order of Spherical Harmonics for correction of PO

EXTERNAL: This is an external email received from the Internet. Report this 
message to s...@aramco.com if the email contains any 
suspicious content.


Normal 0 21 false false false CS X-NONE X-NONE

Dear colleagues,



I use Rietveld method for quantitative phase analysis. I use Topas 5 and now I 
have started using

Spherical Harmonics for correction of preferred orientation (instead of 
March-Dollas correction).

I mainly collect data in Bragg-Brentano geometry; samples are usually prepared 
by front or side-loading.



My question is: Which order of Spherical Harmonics do you recommend to use for 
the purpose of QPA? i.e. for mineral phases like calcite, mica, feldspars, 
plagioclase, kaolinite?

(Most atomic position are usually fixed, refined are only scale factors, 
unit-cell parameters, size, Debye-Waller parameters…).



I know that using high order Spherical Harmonic may lead to nice fits, however 
with meaningless results and therefore the high orders should be used with 
cautions.

I observe the drop of Rwp when introducing the Spherical Harmonics correction 
and when it becomes insignificant, than I reduce the order. E.g. for calcite, 
it is order of 2, for kaolinite order of 4 (i.e. using higher order lead only 
to insignificant drop of Rwp).



Your suggestions, experiences and comments are welcome.



Frantisek Laufek

Czech Geological Survey,

Prague

Czech Republic






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RE: How much COD and PDF database gives the complete known structures?

[Cline, James Dr. (Fed)]

This should be fun to watch…


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 
Shay Tirosh
Sent: Tuesday, January 10, 2017 10:13 AM
To: rietveld_l@ill.fr
Subject: How much COD and PDF database gives the complete known structures?

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
Email: stiro...@gmail.com
_
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++

RE: Stoichiometry and occupancy fractions of solid solutions

[Cline, James Dr. (Fed)]

Luca,

I'd be interested to read your article, but I'm not about to join researchgate 
to do so.

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 
Luca Lutterotti
Sent: Tuesday, December 20, 2016 9:55 AM
To: rietveld_l@ill.fr
Subject: Re: Stoichiometry and occupancy fractions of solid solutions

To increase sensitivity to partial/mixed occupation and also solve the case of 
3 or more atoms in the same site (you have an infinite number of solutions that 
give you the same scattering factor, both x-ray and neutrons) we are developing 
a combined XRD-XRF analysis. Some preliminary application examples were 
published and we are preparing a full article on the theory behind.
https://www.researchgate.net/publication/288701415_Combined_X-Ray_diffraction_and_fluorescence_analysis_in_the_cultural_heritage_field

Best regards,

Luca

---Luca 
Lutterotti
Dipartimento di Ingegneria Industriale, Universita' di Trento,
via Sommarive, 9, 38123 Trento, Italy

e-mail address : luca.luttero...@unitn.it
Maud page : http://maud.radiographema.com

Phone number :+39-0461-28-2414
XRD lab:: +39-0461-282434
Fax : +39-0461-28-1977





On 19 Dec 2016, at 18:23, Vogel, Sven C mailto:s...@lanl.gov>> 
wrote:

Hi Othman,

Another insightful thing to do might be to simulate diffraction patterns for 
various scenarios. If you have B on two sites and simulate if the diffraction 
pattern will look different for different occupancies on those two sites, 
resulting in a given overall stoichiometry, you can convince yourself whether 
diffraction is a good tool to determine SOFs. You can also check which 
diffraction peaks show the biggest change, which may affect your count time or 
region of interest. If you also simulate for neutrons and see a big change for 
neutrons, but not X-rays, you have a good case to supplement a neutron beam 
time proposal.

Good luck,

Sven



From: rietveld_l-requ...@ill.fr 
[rietveld_l-requ...@ill.fr] on behalf of 
Othman Al Bahri [z3435...@zmail.unsw.edu.au]
Sent: Monday, December 19, 2016 1:54 AM
To: rietveld_l@ill.fr
Subject: Stoichiometry and occupancy fractions of solid solutions
Dear all,

I've made a series of solid solution powders using a solid state reaction in 
the form A2B3-xCxO12 at x= 0.5 steps. A2B3O12 is orthorhombic while A2C3O12 is 
monoclinic. I'm refining the XRD data to find the atomic distribution of the 
solute.

I've constrained the sum of the occupancy fractions for each relevant site to 
equal 1. At low concentrations of the solute, I initially set the solute's 
occupancy fractions to 0 and keep the solvent's occupancy at 1 then refine the 
fractions (after following the usual Rietveld refinement steps). This seems to 
give reasonable occupancy fraction values (no big numbers or negative values) 
but the stoichiometry is way off. This is probably because each site has 
different Wykoff multiplicities so constraining the sum of each site's 
fractions to 1 is insufficient.

Let's assume that I knew the stoichiometry from Mass Spectroscopy or XPS - is 
there a way to constrain the stiochiometry in a Rietveld refinement? I'm using 
GSAS-II and comfortable with FullProf but feel free to give advice for any 
other open-source software.

I've seen a few papers where the authors mention, typically in the 
supplementary info, that their refinements' stoichiometry was off and that it 
should be ignored. However I'm not comfortable with this approach and would 
appreciate your advice.

This is my first time working with solid solutions so please feel free to offer 
any general advice on what I should be careful with. I've tested for phase 
mixtures (insolubility) by visually comparing my XRD patterns with the sum of 
simulated XRD patterns of molar mixtures and through Rietveld refinements with 
two phases. The system I'm working with has been reported but the original 
authors didn't do Rietveld refinements - they were interested in physical 
property measurements.

Kind Regards,

Othman
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++

RE: Stoichiometry and occupancy fractions of solid solutions

[Cline, James Dr. (Fed)]

Your data is from where?  I wouldn't trust numbers from refinements as these 
from lab data.

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 
Othman Al Bahri
Sent: Monday, December 19, 2016 3:54 AM
To: rietveld_l@ill.fr
Subject: Stoichiometry and occupancy fractions of solid solutions


Dear all,



I've made a series of solid solution powders using a solid state reaction in 
the form A2B3-xCxO12 at x= 0.5 steps. A2B3O12 is orthorhombic while A2C3O12 is 
monoclinic. I'm refining the XRD data to find the atomic distribution of the 
solute.



I've constrained the sum of the occupancy fractions for each relevant site to 
equal 1. At low concentrations of the solute, I initially set the solute's 
occupancy fractions to 0 and keep the solvent's occupancy at 1 then refine the 
fractions (after following the usual Rietveld refinement steps). This seems to 
give reasonable occupancy fraction values (no big numbers or negative values) 
but the stoichiometry is way off. This is probably because each site has 
different Wykoff multiplicities so constraining the sum of each site's 
fractions to 1 is insufficient.



Let's assume that I knew the stoichiometry from Mass Spectroscopy or XPS - is 
there a way to constrain the stiochiometry in a Rietveld refinement? I'm using 
GSAS-II and comfortable with FullProf but feel free to give advice for any 
other open-source software.



I've seen a few papers where the authors mention, typically in the 
supplementary info, that their refinements' stoichiometry was off and that it 
should be ignored. However I'm not comfortable with this approach and would 
appreciate your advice.



This is my first time working with solid solutions so please feel free to offer 
any general advice on what I should be careful with. I've tested for phase 
mixtures (insolubility) by visually comparing my XRD patterns with the sum of 
simulated XRD patterns of molar mixtures and through Rietveld refinements with 
two phases. The system I'm working with has been reported but the original 
authors didn't do Rietveld refinements - they were interested in physical 
property measurements.



Kind Regards,



Othman
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SRM 1979 now available

[Cline, James Dr. (Fed)]

Hi all,

The new NIST SRM for analysis of crystallite size that I have spoken about on a 
number of occasions over the years is now available.
SRM 1979 - Powder Diffraction Line Profile Standard for Crystallite Size 
Analysis (Nano-Crystalline ZnO Powder)
https://www-s.nist.gov/srmors/view_detail.cfm?srm=1979
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

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RE: U,V,W cagliotti peak width parameters

[Cline, James Dr. (Fed)]

As Alan states, the U, V, and W terms are often employed in situations where 
their physical meaning is minimal:

http://nvlpubs.nist.gov/nistpubs/jres/120/jres.120.013.pdf

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 
Alan Hewat
Sent: Monday, August 29, 2016 7:49 AM
To: Yashwanth Padarthi 
Cc: rietveld_l@ill.fr
Subject: Re: U,V,W cagliotti peak width parameters

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.
 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 
mailto: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 in 
fullprof we can actually vary them individually and see the changes in the 
pattern accordingly by varying U,V,W separately

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   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
mailto:alan.he...@neutronoptics.com>> 
+33.476.98.41.68
http://www.NeutronOptics.com/hewat
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RE: CrySize error in TOPAS

[Cline, James Dr. (Fed)]

That means the value is indeterminate with respect to the refinement and the 
contribution of "CrySize" [crystallite size broadening] to the observation is 
nearly zero.  Try turning it off and see what the residuals do.

Jim


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

-Original Message-
From: "Łukasz Kruszewski" [mailto:lkruszew...@twarda.pan.pl] 
Sent: Wednesday, July 27, 2016 1:08 PM
To: Cline, James Dr. (Fed) 
Cc: rietveld_l@ill.fr; "Łukasz Kruszewski" 
Subject: RE: CrySize error in TOPAS

Hello James. I just read the error that is reported for each refined parameter 
in TOPAS. I obtain value like, e.g., 9000 nm, and the error is, e.g., 205006.

Best regards,

Łukasz Kruszewski


> By what metric are you determining that the CrySize value is in error?
>
>
> James P. Cline
> Materials Measurement Science Division National Institute of Standards 
> and Technology
> 100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ] Gaithersburg, MD 
> 20899-8523    USA jcl...@nist.gov
> (301) 975 5793
> FAX (301) 975 5334
>
> -Original Message-
> From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On 
> Behalf Of "Lukasz Kruszewski"
> Sent: Wednesday, July 27, 2016 10:22 AM
> To: rietveld_l@ill.fr
> Subject: CrySize error in TOPAS
>
> Dera friends,
>
> I'm doing Rietveld refinements in TOPAS; I get rather good fit of the 
> reflections, rather good wt.%, but I've observed large errors for the 
> CrySize (Lorentzian) values for some introduced Structures. I've tried 
> to change it by refining CrySize (Gaussian), but it only changed in 
> few particular cases. I'm rather sure that the intrumental parameters 
> (geometry of the diffractometer was analyzed with the use of LaB6, Si, 
> and other standards) and corrections (sample displ. etc.) are OK and I 
> suppose these factors shouldn't influence (?) the CrySize values. I 
> always constrain the minimum (20 starting value) and maximum (1 
> nm) value for CrySize; I usually refine strain, but I've noticed that 
> it doesn't influence the results (at least the wt.% calculated). Rwp, 
> goodness of fit and Durbin-Watson statistics R values are OK; also, 
> the calculated background line is "flat", i.e., there is no mistaking 
> of the background with reflections; the shapes of the reflections in 
> the calculated diffractograms seem to be OK, too. I was thus wondering 
> if these high errors coming from the CrySize are that important for the 
> refinement?
>
> Best regards,
>
>
> --
> Łukasz Kruszewski, Ph.D., adjunct
> Polish Academy of Sciences
> Institute of Geological Sciences
> Twarda 51/55 str.
> 00-818 Warsaw
> Poland
>


--
Łukasz Kruszewski, Ph.D., adjunct
Polish Academy of Sciences
Institute of Geological Sciences
Twarda 51/55 str.
00-818 Warsaw
Poland
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++

RE: CrySize error in TOPAS

[Cline, James Dr. (Fed)]

By what metric are you determining that the CrySize value is in error?


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

-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of 
"Lukasz Kruszewski"
Sent: Wednesday, July 27, 2016 10:22 AM
To: rietveld_l@ill.fr
Subject: CrySize error in TOPAS

Dera friends,

I'm doing Rietveld refinements in TOPAS; I get rather good fit of the 
reflections, rather good wt.%, but I've observed large errors for the CrySize 
(Lorentzian) values for some introduced Structures. I've tried to change it by 
refining CrySize (Gaussian), but it only changed in few particular cases. I'm 
rather sure that the intrumental parameters (geometry of the diffractometer was 
analyzed with the use of LaB6, Si, and other standards) and corrections (sample 
displ. etc.) are OK and I suppose these factors shouldn't influence (?) the 
CrySize values. I always constrain the minimum (20 starting value) and maximum 
(1 nm) value for CrySize; I usually refine strain, but I've noticed that it 
doesn't influence the results (at least the wt.% calculated). Rwp, goodness of 
fit and Durbin-Watson statistics R values are OK; also, the calculated 
background line is "flat", i.e., there is no mistaking of the background with 
reflections; the shapes of the reflections in the calculated diffractograms 
seem to be OK, too. I was thus wondering if these high errors coming from the 
CrySize are that important for the refinement?

Best regards,


--
Łukasz Kruszewski, Ph.D., adjunct
Polish Academy of Sciences
Institute of Geological Sciences
Twarda 51/55 str.
00-818 Warsaw
Poland
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++

RE: Parafocussing definition?

[Cline, James Dr. (Fed)]

l.fr<mailto:rietveld_l@ill.fr>
Subject: Re: Parafocussing definition?

Am 03/05/2016 um 03:00 schrieb Matthew Rowles:
K&A (and also Brentano, upon rereading) say that in order to be focussing, the 
sample also needs to be toroidally curved; curved along ACB as well as be 
rotated about the axis AB; so it is a little more than the traditional 
flat-sample effect

Yes. And as ACB is not constant, a "focusing sample" should change their 
curvature (bent radius) following the focusing circle versus 2theta,  getting 
more bent with higher diffraction angle, what is hard to do... That's why 
Bragg-Brentano geometry (flat sample) is the working compromise.

Btw, understanding the geometric principles seems to be a bit out of fashion, 
as we nowadays can find "strange" instrumental configurations for common powder 
diffraction work in many laboratories, for example:
- parallel primary beam optics in combination with narrow point detectors,
- overmuch long linear detectors combined with a Bragg-Brentano setup,
- small "antiscatter" slits in front of big linear detectors,
- "knife edge" antiscatter slits above the sample, asymmetrically limiting the 
incident/diffracted beam bundle,
etc. pp

Reinhard





So summarising everyone here, and the papers I've been reading, parafocussing 
means "sort of focussing given the constraints of actually making a physical 
diffractometer". Also, we have a finite source and detector size, and that with 
the dimensions of beam footprint and goniometer radii that we use mean that it 
all pretty much works out in the end.


Matthew

On 2 May 2016 at 20:07, Kern, Arnt 
mailto:arnt.k...@bruker.com>> wrote:
Matthew,

I think Klug & Alexander (1974) give a good explanation about the origin of the 
term "parafocusing": 2nd edition, section "parafocusing methods", page 222 ff.

Cheers,

Arnt

From: rietveld_l-requ...@ill.fr<mailto:rietveld_l-requ...@ill.fr> 
[mailto:rietveld_l-requ...@ill.fr<mailto:rietveld_l-requ...@ill.fr>] On Behalf 
Of Eduard E. Levin
Sent: Montag, 2. Mai 2016 13:21
To: Cline, James Dr. (Fed); Matthew Rowles
Cc: rietveld_l@ill.fr<mailto:rietveld_l@ill.fr>
Subject: RE: Parafocussing definition?

Dear James,

For me too, please, if it would not be much of a trouble.
Thank you in advance!

Eduard

On Mon, 2 May 2016 11:09:31 +, Cline, James Dr. (Fed) wrote
> Bob Cheary and I developed and presented a workshop several times in the 
> 1990's that included a discussion of this issue.  I can send you the notes 
> for it if you would like them.
>
> 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<mailto:jcl...@nist.gov>
> (301) 975 5793
> FAX (301) 975 5334
>
> From: rietveld_l-requ...@ill.fr<mailto:rietveld_l-requ...@ill.fr> 
> [mailto:rietveld_l-requ...@ill.fr<mailto:rietveld_l-requ...@ill.fr>] On 
> Behalf Of Matthew Rowles
> Sent: Monday, May 02, 2016 1:53 AM
> To: RIETVELD_L Distribution List mailto:rietveld_l@ill.fr>>
> Subject: Parafocussing definition?
>
>
> Hi all
>
>
>
> I've been trying to find a good explanation of what parafocussing (wrt 
> Bragg-Brentato geometry) actually is, but haven't been able to find one.
>
>
>
> Klug and Alexander just reference Brentano's papers.
>
>
>
> "The Basics of Crystallography and Diffraction" 2nd ed say that B-B geometry 
> is "semi-focussing" because the sample is flat, and not curved to follow the 
> focussing circle (this doesn't sound right to me)
>
>
>
> Brentano, J Appl. Phys. 17, 420 (1946) says that a ray reflecting off the arc 
> defined by ACB where A is the source, C is the centre of the gonio, and B is 
> the detector (ie the focussing circle)  is automatically parafocussing, 
> because you only can establish the location of the crystallites, not their 
> orientation, but then goes on to say that you can actually find the 
> orientation, as the lattice plane normal bisects the angle ACB.
>
>
>
> I also haven't been able to find a use of the word "parafocus" outside of the 
> diffraction literature, so I can't see how the word is used elsewhere.
>
>
>
> Any ideas?
>
>
>
>
>
> Matthew


--
Open WebMail Project (http://openwebmail.org)






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RE: Parafocussing definition?

[Cline, James Dr. (Fed)]

Bob Cheary and I developed and presented a workshop several times in the 1990’s 
that included a discussion of this issue.  I can send you the notes for it if 
you would like them.

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 
Matthew Rowles
Sent: Monday, May 02, 2016 1:53 AM
To: RIETVELD_L Distribution List 
Subject: Parafocussing definition?

Hi all

I've been trying to find a good explanation of what parafocussing (wrt 
Bragg-Brentato geometry) actually is, but haven't been able to find one.

Klug and Alexander just reference Brentano's papers.

"The Basics of Crystallography and Diffraction" 2nd ed say that B-B geometry is 
"semi-focussing" because the sample is flat, and not curved to follow the 
focussing circle (this doesn't sound right to me)

Brentano, J Appl. Phys. 17, 420 (1946) says that a ray reflecting off the arc 
defined by ACB where A is the source, C is the centre of the gonio, and B is 
the detector (ie the focussing circle)  is automatically parafocussing, because 
you only can establish the location of the crystallites, not their orientation, 
but then goes on to say that you can actually find the orientation, as the 
lattice plane normal bisects the angle ACB.

I also haven't been able to find a use of the word "parafocus" outside of the 
diffraction literature, so I can't see how the word is used elsewhere.

Any ideas?


Matthew
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RE: Aking for Advice - reduce the current to X-ray tube to avoid director saturation at low angels

[Cline, James Dr. (Fed)]

We built an automated anti-scatter slit into which you program the divergence 
slit angle and it adjusts the slit height (over the specimen) with respect to 
Two-Theta during the scan.

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 
Fabrizio Guzzetta
Sent: Sunday, March 06, 2016 12:12 PM
To: iangie 
Cc: Julian Richard Tolchard ; 
rietveld_l@ill.fr
Subject: Re: Aking for Advice - reduce the current to X-ray tube to avoid 
director saturation at low angels

Thanks for the interesting subject. It is really informing and very helpful to 
improve instrumental resolution. P.S. Julian, ever tried additional SAXS 
experiments changing several parameters to optimize your setup? Did you get 
same data on Synchrotron or taking neutron diffraction patterns with the same 
angles range, and setup? May it improve your results? As far as I see you are 
at the ILL so I guess won't be a problem to try these comparisons too. In my 
experience, Sometimes at low angles, commercial instruments just won' t get 
much improvement nonetheless the accuracy of the setup used. At low angles SAXS 
instruments are better than XRD in peak to noise ratio, in my experience

On Sunday, 6 March 2016, iangie mailto:ian...@126.com>> wrote:
Echo
reducing tube power just reducing intensity which reduces your peak height 
together with the background level. It won't help on the peak to background 
ratio.

What you need to improve is the beam path. WhenI was checking the low angle 
beam path, I measured the stage/goniometer dimensions and draw the beam path in 
AutoCAD. And I can calculate the footprint length of illuminated sample 
FP=Rα/Sinθ, where R=goniometer radius; α=divergence slit angle in rad; θ is 
half 2theta. With this equation I can calculate what divergence slit width 
should I use at what θ angle to make sure the beam is not exceed the sample 
area.
If you have a motorised divergence slit, it is highly recommended to use the 
variable divergence slit mode which gradually opens the beam divergence 
(theta-compensating) and guarantees that the FP on sample is constant. With 
this mode, you won't have directe beam on detector.

As Julian mentioned, a knife edge hovering above sample could largely reduce 
air scattering. Anti-scattering slit is not that useful at low angle for PSD.

Cheers,
Tony

发自 网易邮箱大师
On 03/06/2016 19:46, Julian Richard 
Tolchard 
wrote:
Shay,

Can we assume you are working with a reflection mode instrument?

You have two primary sources of background - the primary beam hitting the 
detector directly, and x-rays scattering from the air rather than the sample.

The first of these you control with the divergence slits, but really shouldn't 
be a problem until you go below 4-5 degrees. If you do scan from those sorts of 
angles, set the divergence slits to ~0.1 degrees to keep the beam on the 
sample. I haven't tested it myself, but you could also try reducing the 
detection window on the LynxEye if you want to go to really low angles (<2 
degrees).

The air scatter can be reduced with a special screen/knife that you should have 
received with the instrument, and correctly aligned it will reduce a lot of the 
background increase you see below 10-15 degrees 2-theta. There should be some 
instructions in the instrument manual about this. Using a smaller divergence 
slit (and a receiving slit if you have the option) will also reduce the 
background from airscatter.

I don't think that lowering the tube power will help very much,


jools








From: 
rietveld_l-requ...@ill.fr
 
[rietveld_l-requ...@ill.fr]
 on behalf of Shay Tirosh 
[stiro...@gmail.com]
Sent: 06 March 2016 10:51
To: rietveld_l@ill.fr
Subject: Aking for Advice - reduce the current to X-ray tube to avoid director 
saturation at low angels
Dear Rietvelders

I would like to avoid director saturation (we have a LYNXEYE detector) when I 
work at low angles (lower then 10deg).
I thought it would be good to lower the current tube to reduce the current. say 
to 35mA instead of 40mA.
Can you please comment on problems it should encounter?
Can I correct problems by slowing down my scanning time?

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
Email: stiro...@gmail.com
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