Re: Selective peak broadening - interpretation and handling in FullProf
Dear Radovan and Rietvelders, I apologize for such late response. Here is a plot of FWHM vs 1/d. https://www.dropbox.com/s/ndn58ua1317bmhb/quat_Heusler_FWHM_1%3Ad_plot.pdf?dl=0 All-odd line is nicely shifted as Radovan suggested. According to microstructure analysis for CW method, the plot indicates that all peaks have a strain effect and all-odd peaks have stronger size effect than other peaks. But, is it allowed to apply the idea of FWHM vs.1/d plot both qualitatively and quantitatively to TOF data without any consideration? I am afraid that there would be pitfalls one should avoid. At least, I have noticed that I need to be careful about how to get peak width. In the plot above and the one I posted before, FWHMs are obtained by simple gaussian fitting of individual peak to check the broadening behavior qualitatively. If I want do quantitatively reliable microstructure analysis (I am not sure that there is an established method for TOF data yet), I should take into account rising and decay convolutions to get “real” peak width in addition to instrumental resolution. Then, if I converted TOF profiles into 1/d, I will be stuck because I cannot use a conventional analytical form of a convoluted peak shape function. Or just taking integral breadths is enough? I understand TOF is not suitable for microstructure analysis because peak shape is rather complicated than CW. This is also indicated by the fact that all of the explanations about microstructure analysis which I have read are based on CW and none of them mentioned about TOF. It was not a purpose of our measurement, but I just want to try to extract microstructure information from my TOF data. Best regards, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// > 2015/08/10 16:37、Radovan Cerny <radovan.ce...@unige.ch> のメール： > > Dear Kotaro, > > I think that it is a good track to follow. Compared to Mg(BH4)2 you may have > also chemical order of your four elements ABCD on top of the coherent domains > ordering. Both are of course related. > The antiphase domain ordering is visible in line broadening as a size effect > which is constant in the scale 1/d. It means that it is not constant in the > scale d. Have you plotted your powder pattern in the scale 1/d? > > Best regards > > Radovan > > > Radovan Cerny > Laboratoire de Cristallographie, DQMP > Université de Genève > 24, quai Ernest-Ansermet > CH-1211 Geneva 4, Switzerland > Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 > mailto : radovan.ce...@unige.ch > URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm > > De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part > de Kotaro SAITO > Envoyé : vendredi 7 août 2015 09:49 > À : Alan Hewat; loba...@inorg348-1.chem.msu.ru; Rietveld_l@ill.fr; > l_solov...@yahoo.com > Objet : Re: Selective peak broadening - interpretation and handling in > FullProf > > > Alan and Maxim, > > Thanks for the comment and the article. > I relieved that I know the point. > > > Leonid, > Yes, the instrumental resolution itself increases with d (or TOF). > But it is still strange for me that only all-odd peaks show different > d-dependence from CeO2 and other all-even peaks in terms of slope in the > delta-d/d vs d plot. > > Now, I think a similar situation as high temperature phase of Mg(BH4)2 occurs > in my quaternary Heusler sample. > For all-odd hkl, structure factor is F_hkl=4(f_A-f_C)+/-4i(f_B-f_D). Here, > A-D denote four fcc sublattices in Heusler alloys, or 4a,4c,4b,4d sites in > F-43m. > If there exist ABCD and CDAB type domains, those domain have out-of-phase > scattering for all-odd reflections and same story as Mg(BH4)2 can be applied. > But still I don’t understand why peak widths show such strong dependence on d > (or TOF). > > Concerning attachment files. > This time I use Dropbox but I don’t guarantee it as an image archive because > the image might be removed by me a few years later when I clean up my folders. > > ////// > Kotaro SAITO > High Energy Accelerator Research Organization > Institute of Materials Structure Science > 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan > ////// > > > 2015/08/04 19:34、Alan Hewat <alan.he...@neutronoptics.com> のメール： > > > > On 4 August 2015 at 11:54, Kotaro SAITO <kotaro.sa...@kek.jp> wrote: > > Or do I miss some basic points about diffraction? > > > > I won't try to address yo
RE: Selective peak broadening - interpretation and handling in FullProf
Dear Kotaro, The plot looks nice and convincing. Concerning the propagation of the instrumental resolution in ToF data I prefer that a better expert on ToF data than me answers your question. Best regards Radovan Radovan Cerny Laboratoire de Cristallographie, DQMP Université de Genève 24, quai Ernest-Ansermet CH-1211 Geneva 4, Switzerland Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : radovan.ce...@unige.ch URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm -Message d'origine- De : Kotaro SAITO [mailto:kotaro.sa...@kek.jp] Envoyé : mercredi 30 septembre 2015 10:15 À : Radovan Cerny Cc : Alan Hewat; loba...@inorg348-1.chem.msu.ru; Rietveld_l@ill.fr; l_solov...@yahoo.com Objet : Re: Selective peak broadening - interpretation and handling in FullProf Dear Radovan and Rietvelders, I apologize for such late response. Here is a plot of FWHM vs 1/d. https://www.dropbox.com/s/ndn58ua1317bmhb/quat_Heusler_FWHM_1%3Ad_plot.pdf?dl=0 All-odd line is nicely shifted as Radovan suggested. According to microstructure analysis for CW method, the plot indicates that all peaks have a strain effect and all-odd peaks have stronger size effect than other peaks. But, is it allowed to apply the idea of FWHM vs.1/d plot both qualitatively and quantitatively to TOF data without any consideration? I am afraid that there would be pitfalls one should avoid. At least, I have noticed that I need to be careful about how to get peak width. In the plot above and the one I posted before, FWHMs are obtained by simple gaussian fitting of individual peak to check the broadening behavior qualitatively. If I want do quantitatively reliable microstructure analysis (I am not sure that there is an established method for TOF data yet), I should take into account rising and decay convolutions to get “real” peak width in addition to instrumental resolution. Then, if I converted TOF profiles into 1/d, I will be stuck because I cannot use a conventional analytical form of a convoluted peak shape function. Or just taking integral breadths is enough? I understand TOF is not suitable for microstructure analysis because peak shape is rather complicated than CW. This is also indicated by the fact that all of the explanations about microstructure analysis which I have read are based on CW and none of them mentioned about TOF. It was not a purpose of our measurement, but I just want to try to extract microstructure information from my TOF data. Best regards, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// > 2015/08/10 16:37、Radovan Cerny <radovan.ce...@unige.ch> のメール： > > Dear Kotaro, > > I think that it is a good track to follow. Compared to Mg(BH4)2 you may have > also chemical order of your four elements ABCD on top of the coherent domains > ordering. Both are of course related. > The antiphase domain ordering is visible in line broadening as a size effect > which is constant in the scale 1/d. It means that it is not constant in the > scale d. Have you plotted your powder pattern in the scale 1/d? > > Best regards > > Radovan > > > Radovan Cerny > Laboratoire de Cristallographie, DQMP > Université de Genève > 24, quai Ernest-Ansermet > CH-1211 Geneva 4, Switzerland > Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : > radovan.ce...@unige.ch > URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm > > De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De > la part de Kotaro SAITO Envoyé : vendredi 7 août 2015 09:49 À : Alan > Hewat; loba...@inorg348-1.chem.msu.ru; Rietveld_l@ill.fr; > l_solov...@yahoo.com Objet : Re: Selective peak broadening - > interpretation and handling in FullProf > > > Alan and Maxim, > > Thanks for the comment and the article. > I relieved that I know the point. > > > Leonid, > Yes, the instrumental resolution itself increases with d (or TOF). > But it is still strange for me that only all-odd peaks show different > d-dependence from CeO2 and other all-even peaks in terms of slope in the > delta-d/d vs d plot. > > Now, I think a similar situation as high temperature phase of Mg(BH4)2 occurs > in my quaternary Heusler sample. > For all-odd hkl, structure factor is F_hkl=4(f_A-f_C)+/-4i(f_B-f_D). Here, > A-D denote four fcc sublattices in Heusler alloys, or 4a,4c,4b,4d sites in > F-43m. > If there exist ABCD and CDAB type domains, those domain have out-of-phase > scattering for all-odd reflections and same story as Mg(BH4)2 can be ap
RE: Selective peak broadening - interpretation and handling in FullProf
Dear Kotaro, I think that it is a good track to follow. Compared to Mg(BH4)2 you may have also chemical order of your four elements ABCD on top of the coherent domains ordering. Both are of course related. The antiphase domain ordering is visible in line broadening as a size effect which is constant in the scale 1/d. It means that it is not constant in the scale d. Have you plotted your powder pattern in the scale 1/d? Best regards Radovan Radovan Cerny Laboratoire de Cristallographie, DQMP Université de Genève 24, quai Ernest-Ansermet CH-1211 Geneva 4, Switzerland Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : radovan.ce...@unige.ch URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part de Kotaro SAITO Envoyé : vendredi 7 août 2015 09:49 À : Alan Hewat; loba...@inorg348-1.chem.msu.ru; Rietveld_l@ill.fr; l_solov...@yahoo.com Objet : Re: Selective peak broadening - interpretation and handling in FullProf Alan and Maxim, Thanks for the comment and the article. I relieved that I know the point. Leonid, Yes, the instrumental resolution itself increases with d (or TOF). But it is still strange for me that only all-odd peaks show different d-dependence from CeO2 and other all-even peaks in terms of slope in the delta-d/d vs d plot. Now, I think a similar situation as high temperature phase of Mg(BH4)2 occurs in my quaternary Heusler sample. For all-odd hkl, structure factor is F_hkl=4(f_A-f_C)+/-4i(f_B-f_D). Here, A-D denote four fcc sublattices in Heusler alloys, or 4a,4c,4b,4d sites in F-43m. If there exist ABCD and CDAB type domains, those domain have out-of-phase scattering for all-odd reflections and same story as Mg(BH4)2 can be applied. But still I don’t understand why peak widths show such strong dependence on d (or TOF). Concerning attachment files. This time I use Dropbox but I don’t guarantee it as an image archive because the image might be removed by me a few years later when I clean up my folders. ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// 2015/08/04 19:34、Alan Hewat alan.he...@neutronoptics.commailto:alan.he...@neutronoptics.com のメール： On 4 August 2015 at 11:54, Kotaro SAITO kotaro.sa...@kek.jpmailto:kotaro.sa...@kek.jp wrote: Or do I miss some basic points about diffraction? I won't try to address your specific material... and I'm being called to lunch :-) But for beginners who may be lost in these technical papers, I will attempt the following trivial explanation If you have a layered material where two layers A and B are slightly different you will have super-structure reflections. These will be as sharp as the main reflections (from the average structure) if the order of the layers is perfectly regular ABABABAB... But if the layers only have short-range order eg ABABBABAAB... then these superlattice reflections will be broadened, and even completely washed out if the order between layers is completely random. Otherwise the width delta-d of the superstructure reflections will give you the short range order length - the shorter the correlation length the broader the superlattice reflections. Obviously delta-d doesn't depend on the d-spacing between layers, only on the length of their order. So the broadening is constant in d-space as usually plotted for TOF neutron diffraction. For angular dispersion eg with a constant x-ray or neutron wavelength, Bragg's law 2d.sin(theta)=lambda comes in. If you differentiate Bragg's law you will find a simple relation between delta-d and delta-2theta, the line broadening for angular dispersion measurements. Alan. (Everything should be as simple as possible... but no simpler.) BTW, thanks for using dropbox instead of an attachment. That's the way to go... -- __ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE alan.he...@neutronoptics.commailto:alan.he...@neutronoptics.com +33.476.98.41.68 http://www.NeutronOptics.com/hewat __ ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.commailto:alan.he...@neutronoptics.com Send commands to lists...@ill.frmailto: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/ ++ ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.commailto:alan.he...@neutronoptics.com Send commands to lists...@ill.frmailto:lists...@ill.fr eg: HELP as the subject
Re: Selective peak broadening - interpretation and handling in FullProf
Alan and Maxim, Thanks for the comment and the article. I relieved that I know the point. Leonid, Yes, the instrumental resolution itself increases with d (or TOF). But it is still strange for me that only all-odd peaks show different d-dependence from CeO2 and other all-even peaks in terms of slope in the delta-d/d vs d plot. Now, I think a similar situation as high temperature phase of Mg(BH4)2 occurs in my quaternary Heusler sample. For all-odd hkl, structure factor is F_hkl=4(f_A-f_C)+/-4i(f_B-f_D). Here, A-D denote four fcc sublattices in Heusler alloys, or 4a,4c,4b,4d sites in F-43m. If there exist ABCD and CDAB type domains, those domain have out-of-phase scattering for all-odd reflections and same story as Mg(BH4)2 can be applied. But still I don’t understand why peak widths show such strong dependence on d (or TOF). Concerning attachment files. This time I use Dropbox but I don’t guarantee it as an image archive because the image might be removed by me a few years later when I clean up my folders. ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// 2015/08/04 19:34、Alan Hewat alan.he...@neutronoptics.com のメール： On 4 August 2015 at 11:54, Kotaro SAITO kotaro.sa...@kek.jp wrote: Or do I miss some basic points about diffraction? I won't try to address your specific material... and I'm being called to lunch :-) But for beginners who may be lost in these technical papers, I will attempt the following trivial explanation If you have a layered material where two layers A and B are slightly different you will have super-structure reflections. These will be as sharp as the main reflections (from the average structure) if the order of the layers is perfectly regular ABABABAB... But if the layers only have short-range order eg ABABBABAAB... then these superlattice reflections will be broadened, and even completely washed out if the order between layers is completely random. Otherwise the width delta-d of the superstructure reflections will give you the short range order length - the shorter the correlation length the broader the superlattice reflections. Obviously delta-d doesn't depend on the d-spacing between layers, only on the length of their order. So the broadening is constant in d-space as usually plotted for TOF neutron diffraction. For angular dispersion eg with a constant x-ray or neutron wavelength, Bragg's law 2d.sin(theta)=lambda comes in. If you differentiate Bragg's law you will find a simple relation between delta-d and delta-2theta, the line broadening for angular dispersion measurements. Alan. (Everything should be as simple as possible... but no simpler.) BTW, thanks for using dropbox instead of an attachment. That's the way to go... -- __ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE alan.he...@neutronoptics.com +33.476.98.41.68 http://www.NeutronOptics.com/hewat __ ++ 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/ ++ ++ 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/ ++
Re: Selective peak broadening - interpretation and handling in FullProf
On 4 August 2015 at 11:54, Kotaro SAITO kotaro.sa...@kek.jp wrote: Or do I miss some basic points about diffraction? I won't try to address your specific material... and I'm being called to lunch :-) But for beginners who may be lost in these technical papers, I will attempt the following trivial explanation If you have a layered material where two layers A and B are slightly different you will have super-structure reflections. These will be as sharp as the main reflections (from the average structure) if the order of the layers is perfectly regular ABABABAB... But if the layers only have short-range order eg ABABBABAAB... then these superlattice reflections will be broadened, and even completely washed out if the order between layers is completely random. Otherwise the width delta-d of the superstructure reflections will give you the short range order length - the shorter the correlation length the broader the superlattice reflections. Obviously delta-d doesn't depend on the d-spacing between layers, only on the length of their order. So the broadening is constant in d-space as usually plotted for TOF neutron diffraction. For angular dispersion eg with a constant x-ray or neutron wavelength, Bragg's law 2d.sin(theta)=lambda comes in. If you differentiate Bragg's law you will find a simple relation between delta-d and delta-2theta, the line broadening for angular dispersion measurements. Alan. (Everything should be as simple as possible... but no simpler.) BTW, thanks for using dropbox instead of an attachment. That's the way to go... -- __ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * alan.he...@neutronoptics.com +33.476.98.41.68 http://www.NeutronOptics.com/hewat __ ++ 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/ ++
Re: Selective peak broadening - interpretation and handling in FullProf
Dear Kotaro, The microstructure-related peak broadening always increase with 2Theta (and decrease with d). In your case, I suspect, the increase of FWHM with d might be due to an instrumental contribution, as the general trend looks similar to that of the CeO2 standard. Best regards, Leonid *** Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660036, Akademgorodok 50/24, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid *** - Original Message - From: Kotaro SAITO kotaro.sa...@kek.jp To: Radovan Cerny radovan.ce...@unige.ch; l_solov...@yahoo.com Cc: Rietveld_l@ill.fr Rietveld_l@ill.fr Sent: Tuesday, August 4, 2015 4:54 PM Subject: Re: Selective peak broadening - interpretation and handling in FullProf Dear Radovan and Leonid, Thanks for your comments. Both papers are very interesting and seem to contain good hints for my case. Now I am confusing when I compare peak width vs. 2th in constant wave profiles and peak width vs. d in TOF. When I plot FWHM/d vs. d, FWHM/d of all-odd peaks increases with increasing d. (Note these FWHM are obtained with multiple peak fitting with simple Gaussian.) In other words, peak broadening is large for small hkl peaks. Here is the plot. (not an attachment file!) https://www.dropbox.com/s/uzm0fv3q8ljoq5o/Layout0.pdf?dl=0 On the other hand, for example Fig.3 in Leonid’s paper (http://dx.doi.org/10.1107/S00218898114X), peak broadening is larger for large 2th, which means large hkl peaks. If the peak broadening in my TOF data has a similar origin as two papers which Radovan and Leonid showed, is it acceptable to have such different hkl dependence between TOF and 2th data? Or do I miss some basic points about diffraction? Best regards, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// ++ 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/ ++
Re: Selective peak broadening - interpretation and handling in FullProf
Dear Radovan and Leonid, Thanks for your comments. Both papers are very interesting and seem to contain good hints for my case. Now I am confusing when I compare peak width vs. 2th in constant wave profiles and peak width vs. d in TOF. When I plot FWHM/d vs. d, FWHM/d of all-odd peaks increases with increasing d. (Note these FWHM are obtained with multiple peak fitting with simple Gaussian.) In other words, peak broadening is large for small hkl peaks. Here is the plot. (not an attachment file!) https://www.dropbox.com/s/uzm0fv3q8ljoq5o/Layout0.pdf?dl=0 On the other hand, for example Fig.3 in Leonid’s paper (http://dx.doi.org/10.1107/S00218898114X), peak broadening is larger for large 2th, which means large hkl peaks. If the peak broadening in my TOF data has a similar origin as two papers which Radovan and Leonid showed, is it acceptable to have such different hkl dependence between TOF and 2th data? Or do I miss some basic points about diffraction? Best regards, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// 2015/07/31 17:13、Radovan Cerny radovan.ce...@unige.ch のメール： Dear Kotaro, The same rule of line broadening was observed in beta phase of Mg(BH4)2, and was explained as ordering of twin domains, in other words microtwinning which creates a superstructure to the even,even,even subcell. If the twinning probability is not 100%, then the odd,odd,odd reflections broaden till they disappear. You may find an inspiration in Acta Cryst. (2007). B63, 561-568[ doi:10.1107/S0108768107022665 ] Structure of unsolvated magnesium borohydride Mg(BH4)2 J.-H. Her, P. W. Stephens, Y. Gao, G. L. Soloveichik, J. Rijssenbeek, M. Andrus and J.-C. Zhao In Fullprof there are few models of line broadening, but I do not know whether any of them can be used for your case. In Topas you may create any model of line broadening using the macro language. Hope it helps Radovan Radovan Cerny Laboratoire de Cristallographie, DQMP Université de Genève 24, quai Ernest-Ansermet CH-1211 Geneva 4, Switzerland Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : radovan.ce...@unige.ch URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part de Kotaro SAITO Envoyé : vendredi 31 juillet 2015 09:15 À : Rietveld_l@ill.fr Objet : Selective peak broadening - interpretation and handling in FullProf Dear Rietvelders, There is two things I would like to ask. 1. Physical interpretation of selective peak broadening I have a difficulty in interpreting selective peak broadening in my TOF data of quaternary Heusler alloy. All peaks for all-odd hkl reflections show significant broadening (about 25% increase from the instrumental resolution for small d range and 100% increase for large d range). Other peaks for all-even hkl stay in the instrumental resolution for whole d range. If hkl reflections for one specific direction show broadening, it might be easier to interpret. But this time, it is not the case. (eg. 111 reflection shows significant broadening but 222 does not.) If I write the sample's chemical formula as ABCD, 4 sites in the Heusler alloy along [111] direction seems to be (A,B)-(C,D)-(C,D)-(A,B) with different site mixing ratio according to brief analysis. One thing I have noticed is that each lattice plane for all-odd hkl consists of one sublattice. For the case of 111 reflection, which is the easiest case, first plane at the origin consists only (A,B). Second plane consists only (C,D), and so on. This holds for other all-odd hkl reflections Does anyone know good literatures to get some hints for this? I have checked “Defect and Microstructure Analysis by Diffraction” by Snyder, Fiala, and Bunge, but I couldn’t find descriptions about selective peak broadening. 2. Handling selective peak broadening in FullProf The manual says “there is a number of size models built into FullProf corresponding to particular sets of reflections that are affected from broadening.” But I only find Size-Model=14 and -2 (to -9) in the manual for that purpose. Are there any models other than these? And, does anyone know what Size-Model=14 is? The manual only shows a result using Size-Model=14 (Figure 2) without any explanations. I have already tried Size-Model=-2 and it works well but not sufficient for 111 peak which shows the largest broadening. (and it does not gives me any physical interpretation, of course.) Best, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure
Selective peak broadening - interpretation and handling in FullProf
Dear Rietvelders, There is two things I would like to ask. 1. Physical interpretation of selective peak broadening I have a difficulty in interpreting selective peak broadening in my TOF data of quaternary Heusler alloy. All peaks for all-odd hkl reflections show significant broadening (about 25% increase from the instrumental resolution for small d range and 100% increase for large d range). Other peaks for all-even hkl stay in the instrumental resolution for whole d range. If hkl reflections for one specific direction show broadening, it might be easier to interpret. But this time, it is not the case. (eg. 111 reflection shows significant broadening but 222 does not.) If I write the sample's chemical formula as ABCD, 4 sites in the Heusler alloy along [111] direction seems to be (A,B)-(C,D)-(C,D)-(A,B) with different site mixing ratio according to brief analysis. One thing I have noticed is that each lattice plane for all-odd hkl consists of one sublattice. For the case of 111 reflection, which is the easiest case, first plane at the origin consists only (A,B). Second plane consists only (C,D), and so on. This holds for other all-odd hkl reflections Does anyone know good literatures to get some hints for this? I have checked “Defect and Microstructure Analysis by Diffraction” by Snyder, Fiala, and Bunge, but I couldn’t find descriptions about selective peak broadening. 2. Handling selective peak broadening in FullProf The manual says “there is a number of size models built into FullProf corresponding to particular sets of reflections that are affected from broadening.” But I only find Size-Model=14 and -2 (to -9) in the manual for that purpose. Are there any models other than these? And, does anyone know what Size-Model=14 is? The manual only shows a result using Size-Model=14 (Figure 2) without any explanations. I have already tried Size-Model=-2 and it works well but not sufficient for 111 peak which shows the largest broadening. (and it does not gives me any physical interpretation, of course.) Best, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// ++ 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/ ++
Re: Selective peak broadening - interpretation and handling in FullProf
Dear Kotaro, The broadening you describe seems to be due to a non-uniform distribution of site occupancies in the crystal lattice. A general model for such defect-related broadening is described here: http://dx.doi.org/10.1107/S00218898114X The model is included into the DDM program (but it doesn't handle TOF data, unfortunately). Hope this helps, Leonid *** Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660036, Akademgorodok 50/24, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid *** - Original Message - From: Kotaro SAITO kotaro.sa...@kek.jp To: Rietveld_l@ill.fr Cc: Sent: Friday, July 31, 2015 2:14 PM Subject: Selective peak broadening - interpretation and handling in FullProf Dear Rietvelders, There is two things I would like to ask. 1. Physical interpretation of selective peak broadening I have a difficulty in interpreting selective peak broadening in my TOF data of quaternary Heusler alloy. All peaks for all-odd hkl reflections show significant broadening (about 25% increase from the instrumental resolution for small d range and 100% increase for large d range). Other peaks for all-even hkl stay in the instrumental resolution for whole d range. If hkl reflections for one specific direction show broadening, it might be easier to interpret. But this time, it is not the case. (eg. 111 reflection shows significant broadening but 222 does not.) If I write the sample's chemical formula as ABCD, 4 sites in the Heusler alloy along [111] direction seems to be (A,B)-(C,D)-(C,D)-(A,B) with different site mixing ratio according to brief analysis. One thing I have noticed is that each lattice plane for all-odd hkl consists of one sublattice. For the case of 111 reflection, which is the easiest case, first plane at the origin consists only (A,B). Second plane consists only (C,D), and so on. This holds for other all-odd hkl reflections Does anyone know good literatures to get some hints for this? I have checked “Defect and Microstructure Analysis by Diffraction” by Snyder, Fiala, and Bunge, but I couldn’t find descriptions about selective peak broadening. 2. Handling selective peak broadening in FullProf The manual says “there is a number of size models built into FullProf corresponding to particular sets of reflections that are affected from broadening.” But I only find Size-Model=14 and -2 (to -9) in the manual for that purpose. Are there any models other than these? And, does anyone know what Size-Model=14 is? The manual only shows a result using Size-Model=14 (Figure 2) without any explanations. I have already tried Size-Model=-2 and it works well but not sufficient for 111 peak which shows the largest broadening. (and it does not gives me any physical interpretation, of course.) Best, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// ++ 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/ ++
RE: Selective peak broadening - interpretation and handling in FullProf
Dear Kotaro, The same rule of line broadening was observed in beta phase of Mg(BH4)2, and was explained as ordering of twin domains, in other words microtwinning which creates a superstructure to the even,even,even subcell. If the twinning probability is not 100%, then the odd,odd,odd reflections broaden till they disappear. You may find an inspiration in Acta Cryst. (2007). B63, 561-568[ doi:10.1107/S0108768107022665http://dx.doi.org/10.1107/S0108768107022665 ] Structure of unsolvated magnesium borohydride Mg(BH4)2 J.-H. Herhttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Her,%20J.-H., P. W. Stephenshttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Stephens,%20P.W., Y. Gaohttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Gao,%20Y., G. L. Soloveichikhttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Soloveichik,%20G.L., J. Rijssenbeekhttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Rijssenbeek,%20J., M. Andrushttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Andrus,%20M. and J.-C. Zhaohttp://scripts.iucr.org/cgi-bin/citedin?search_on=nameauthor_name=Zhao,%20J.-C. In Fullprof there are few models of line broadening, but I do not know whether any of them can be used for your case. In Topas you may create any model of line broadening using the macro language. Hope it helps Radovan Radovan Cerny Laboratoire de Cristallographie, DQMP Université de Genève 24, quai Ernest-Ansermet CH-1211 Geneva 4, Switzerland Phone : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : radovan.ce...@unige.ch URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part de Kotaro SAITO Envoyé : vendredi 31 juillet 2015 09:15 À : Rietveld_l@ill.fr Objet : Selective peak broadening - interpretation and handling in FullProf Dear Rietvelders, There is two things I would like to ask. 1. Physical interpretation of selective peak broadening I have a difficulty in interpreting selective peak broadening in my TOF data of quaternary Heusler alloy. All peaks for all-odd hkl reflections show significant broadening (about 25% increase from the instrumental resolution for small d range and 100% increase for large d range). Other peaks for all-even hkl stay in the instrumental resolution for whole d range. If hkl reflections for one specific direction show broadening, it might be easier to interpret. But this time, it is not the case. (eg. 111 reflection shows significant broadening but 222 does not.) If I write the sample's chemical formula as ABCD, 4 sites in the Heusler alloy along [111] direction seems to be (A,B)-(C,D)-(C,D)-(A,B) with different site mixing ratio according to brief analysis. One thing I have noticed is that each lattice plane for all-odd hkl consists of one sublattice. For the case of 111 reflection, which is the easiest case, first plane at the origin consists only (A,B). Second plane consists only (C,D), and so on. This holds for other all-odd hkl reflections Does anyone know good literatures to get some hints for this? I have checked “Defect and Microstructure Analysis by Diffraction” by Snyder, Fiala, and Bunge, but I couldn’t find descriptions about selective peak broadening. 2. Handling selective peak broadening in FullProf The manual says “there is a number of size models built into FullProf corresponding to particular sets of reflections that are affected from broadening.” But I only find Size-Model=14 and -2 (to -9) in the manual for that purpose. Are there any models other than these? And, does anyone know what Size-Model=14 is? The manual only shows a result using Size-Model=14 (Figure 2) without any explanations. I have already tried Size-Model=-2 and it works well but not sufficient for 111 peak which shows the largest broadening. (and it does not gives me any physical interpretation, of course.) Best, Kotaro ////// Kotaro SAITO High Energy Accelerator Research Organization Institute of Materials Structure Science 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan ////// ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.commailto:alan.he...@neutronoptics.com Send commands to lists...@ill.frmailto: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/ ++ ++ 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/ ++
