Hello Simona. Thank you for the tip. Can you please tell me which refined
parameters did you mean? I suppose you've meant the Sample Corrections and
not the Intstrumental Parameters?
Best regards,
Luke Kruszewski
> Dear Lukasz, dear all:
>
> Before eliminating the contribution of the sample to peak broadening (i.e.
> before suppressing the CS_L instruction), it would be safer to understand
> if the value of 9000 nm is sensible or not. Make sure that there is no
> refined variable, in your input, contributing too much to peak broadening.
> If this variable exists, the high value of the crystal simply tries to
> counterbalance the broadening effect of that variable.
>
> In this respect, I would follow Peter'suggestion to go carefully through
> the correlation matrix provided by Topas when do_errors is at work and
> verify if CS_L strongly correlates with some other variable.
>
> Kind regards,
> Simona
>
>
> Simona Galli, Prof.
> Dipartimento di Scienza e Alta Tecnologia
> Università dell'Insubria
> Via Valleggio, 9
> 22100 Como - Italy
>
> e-mail: simona.ga...@uninsubria.it
> tel: +39-031-2386627
> url: scienze-como.uninsubria.it/sgalli
>
> Treasurer of the Italian Crystallographic Association
> tesori...@cristallografia.org
>
>
> - Messaggio originale -
> Da: "Cline, James Dr. (Fed)"
> Inviato: 27/07/2016 19:17
> A: "rietveld_l@ill.fr"
> Cc: ""Łukasz Kruszewski""
> Oggetto: RE: CrySize error in TOPAS
>
> 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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