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) <james.cl...@nist.gov> Cc: rietveld_l@ill.fr; "Łukasz Kruszewski" <lkruszew...@twarda.pan.pl> 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 (10000 > 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
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
