Re: refinement
Nice job !Happy new year.Armelenvoyé : 6 janvier 2023 à 12:36de : Frank Girgsdies à : KULDEEP SINGH <2019phdph...@curaj.ac.in>, rietveld_l@ill.frobjet : Re: refinementDear Kuldeep,First of all, a refinement (I suppose you mean Rietveld refinement?) requires a crystal structure model, which in turn requires that you have a rather precise knowledge about the identity/composition of the crystalline phase you want to refine. XRD is not an elemental analysis method, and perovskite structures can be formed with many, many elements. Unfortunately, you forgot to mention what elements your material is composed of.I tired an identification anyway, using the latest edition of the PDF-4+ database. However, despite the fact that the pattern looks definitely perovskite-like, there was no match close enough. Trying to tune the lattice parameters of some better candidate structures revealed that something is weird about your pattern, as the positions of related reflections do not agree with each other.Then I tried to shift the pattern on a trial-and-error basis and found that it has in fact a severe zero shift of more than 0.4 degrees 2theta. It could also be a serious sample height (a.k.a. displacement) error, since these two errors are rather similar in effect. However, in order to refine a displacement correction, I would need to know your goniometer radius.I performed a Le Bail fit assuming a GdFeO3 type structure (in setting Pbnm) and obtained a reasonable fit yielding the following lattice parameters:a = 5.26617(12) Åb = 5.62135(16) Åc = 7.48743(19) Åzero error = -0.4428(8) deg. 2thetaWith this zero error information, I went back to the PDF search.Based on that, my best guess is that your sample could be Ho(Cr0.5Mn0.5)O3.Best wishes and Happy New Year,Frank GirgsdiesOn 23.12.2022 06:16, KULDEEP SINGH wrote:Hi all,please help to refine this simple data of perovskite i am stuck in it.angle 20-80step size 0.01wavelength 1.5404*Kuldeep Singh**Research Scholar**Department of PhysicsCentral University of Rajasthan**Bandarsindri-305817**District-Ajmer, Rajasthan*ᐧ++Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body textThe Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body textThe Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/++ ++ Please do NOT attach files to the whole list Send commands to 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: refinement
Dear Kuldeep, First of all, a refinement (I suppose you mean Rietveld refinement?) requires a crystal structure model, which in turn requires that you have a rather precise knowledge about the identity/composition of the crystalline phase you want to refine. XRD is not an elemental analysis method, and perovskite structures can be formed with many, many elements. Unfortunately, you forgot to mention what elements your material is composed of. I tired an identification anyway, using the latest edition of the PDF-4+ database. However, despite the fact that the pattern looks definitely perovskite-like, there was no match close enough. Trying to tune the lattice parameters of some better candidate structures revealed that something is weird about your pattern, as the positions of related reflections do not agree with each other. Then I tried to shift the pattern on a trial-and-error basis and found that it has in fact a severe zero shift of more than 0.4 degrees 2theta. It could also be a serious sample height (a.k.a. displacement) error, since these two errors are rather similar in effect. However, in order to refine a displacement correction, I would need to know your goniometer radius. I performed a Le Bail fit assuming a GdFeO3 type structure (in setting Pbnm) and obtained a reasonable fit yielding the following lattice parameters: a = 5.26617(12) Å b = 5.62135(16) Å c = 7.48743(19) Å zero error = -0.4428(8) deg. 2theta With this zero error information, I went back to the PDF search. Based on that, my best guess is that your sample could be Ho(Cr0.5Mn0.5)O3. Best wishes and Happy New Year, Frank Girgsdies On 23.12.2022 06:16, KULDEEP SINGH wrote: Hi all, please help to refine this simple data of perovskite i am stuck in it. angle 20-80 step size 0.01 wavelength 1.5404 *Kuldeep Singh* *Research Scholar* *Department of Physics Central University of Rajasthan * *Bandarsindri-305817* *District-Ajmer, Rajasthan* ᐧ ++ Please do NOT attach files to the whole list Send commands to 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 Send commands to 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: refinement
Ok Sir, I will take care of it, next time Thank you On Fri, Dec 23, 2022, 13:06 Alan W Hewat wrote: > "Please do NOT attach files to the whole list". > This message appears immediately before the file you attached to the whole > list. If you do it again, you will be removed from the list. Please read > the instructions for your refinement program and try again. If you really > are stuck, say something specific about the problem you have. What > experience do you have? If you are a student, get help first from your > local professor or another colleague. > > Best wishes to all for the end of year celebrations, and a happy New Year. > > Alan > > Dr Alan Hewat, NeutronOptics > Grenoble, FRANCE (from phone) > alan.he...@neutronoptics.com > +33.476984168 VAT:FR79499450856 > http://NeutronOptics.com/hewat > ___ > > > On Fri, 23 Dec 2022, 06:17 KULDEEP SINGH, <2019phdph...@curaj.ac.in> > wrote: > >> Hi all, >> please help to refine this simple data of perovskite i am stuck in it. >> angle 20-80 >> step size 0.01 >> wavelength 1.5404 >> *Kuldeep Singh* >> *Research Scholar* >> >> >> *Department of PhysicsCentral University of Rajasthan* >> *Bandarsindri-305817* >> *District-Ajmer, Rajasthan* >> ᐧ >> ++ >> Please do NOT attach files to the whole list > > >> Send commands to 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 Send commands to 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: refinement
"Please do NOT attach files to the whole list". This message appears immediately before the file you attached to the whole list. If you do it again, you will be removed from the list. Please read the instructions for your refinement program and try again. If you really are stuck, say something specific about the problem you have. What experience do you have? If you are a student, get help first from your local professor or another colleague. Best wishes to all for the end of year celebrations, and a happy New Year. Alan Dr Alan Hewat, NeutronOptics Grenoble, FRANCE (from phone) alan.he...@neutronoptics.com +33.476984168 VAT:FR79499450856 http://NeutronOptics.com/hewat ___ On Fri, 23 Dec 2022, 06:17 KULDEEP SINGH, <2019phdph...@curaj.ac.in> wrote: > Hi all, > please help to refine this simple data of perovskite i am stuck in it. > angle 20-80 > step size 0.01 > wavelength 1.5404 > *Kuldeep Singh* > *Research Scholar* > > > *Department of PhysicsCentral University of Rajasthan* > *Bandarsindri-305817* > *District-Ajmer, Rajasthan* > ᐧ > ++ > Please do NOT attach files to the whole list > > Send commands to 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 Send commands to 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: refinement
Your pattern match well with Bixbyite (plus some impurity)http://www.crystallography.net/cod/9007522.htmlUsing FPSM http://nanoair.dii.unitn.it:8080/sfpm/BestArmelenvoyé : 15 septembre 2022 à 18:37de : KULDEEP SINGH <2019phdph...@curaj.ac.in>à : rietveld_l@ill.frobjet : refinementAnybody can provide me Rietveld refinement of the following data.angle 10-90scane step 0.01Pyrochlore compound Fe2Mn2O7Kuldeep SinghResearch ScholarDepartment of PhysicsCentral University of RajasthanBandarsindri-305817District-Ajmer, Rajasthanᐧ++Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body textThe Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/++ ++ Please do NOT attach files to the whole list Send commands to 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: Refinement of birnessite type layered manganese oxides
Dear Nadya, I would recommend the use of the program FAULTS to refine powder diffraction data of your birnessite-type layered manganese oxides containing stacking faults. FAULTS is indeed a program developed for the refinement of diffraction data of materials with planar defects, and in particular layered materials having stacking faults. This program is included in the FullProf Suite (https://www.ill.eu/sites/fullprof/ ) and it is also available as a separate program at this webpage: http://www.cicenergigune.com/faults . We have recently published a paper describing the program FAULTS, including several examples of refinements: in particular a sample layered oxide Li2PtO3 which presents stacking faults and a sample of gamma-MnO2 which is an intergrowth of pyrolusite and ramsdellite structures. You can find this article here: http://scripts.iucr.org/cgi-bin/paper?kc5049 (Casas-Cabanas et al. J Appl. Cryst 216, 49, p2259-2269). If you need more information about FAULTS, or some support, do not hesitate to contact us at fau...@cicenergigune.com Best regards Marine Marine Reynaud Post-Doctoral Researcher Structure and Surface Analysis CIC Energigune Parque Tecnológico C/ Albert Einstein, 48 01510 Miñano (Álava) Spain Tel: +34 945 297 108 or +34 911 922 137 ext. 380 E-mail: mreyn...@cicenergigune.com www.cicenergigune.com -Mensaje original- De: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] En nombre de GREGORKIEWITZ MICHAEL Enviado el: martes, 17 de enero de 2017 16:50 Para: Nayda Patricia Arias Duque CC: rietveld_l@ill.fr Asunto: Re: Refinement of birnessite type layered manganese oxides dear Nayda, a bit late, but may be still useful for you: we worked on Rietveld refinement of a birnessite impurity considering various stacking types - without much success, but in our ms you can find references to different models, and a quite surprising result for our "birnessite" sample. Our article is free access and can be found in Acta Cryst B dec 2016 or on researchgate. Best Miguel --- michele gregorkiewitz Dip Scienze Fisiche, della Terra e dell'Ambiente Università di Siena via Laterina 8, I-53100 Siena gre...@unisi.it, +39'0577'233810 Il 2016-12-22 00:51 Nayda Patricia Arias Duque ha scritto: > Hello . > > I am trying to refine birnessite type layered manganese oxides and I > want to know how can I identify stacking faults on this type of > materials?. > > Thank you in advance for your information, > > Best Regards and Merry Christmas > > Nayda Patricia Arias Duque > PhD Candidate in Chemical Engineering > Nanostructured and Functional Materials Laboratory National University > of Colombia- Manizales Campus www.unal.edu.co [1] > > Links: > -- > [1] http://www.unal.edu.co > ++ > Please do NOT attach files to the whole list > Send commands to 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 Send commands to 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: Refinement of birnessite type layered manganese oxides
dear Nayda, a bit late, but may be still useful for you: we worked on Rietveld refinement of a birnessite impurity considering various stacking types - without much success, but in our ms you can find references to different models, and a quite surprising result for our "birnessite" sample. Our article is free access and can be found in Acta Cryst B dec 2016 or on researchgate. Best Miguel --- michele gregorkiewitz Dip Scienze Fisiche, della Terra e dell'Ambiente Università di Siena via Laterina 8, I-53100 Siena gre...@unisi.it, +39'0577'233810 Il 2016-12-22 00:51 Nayda Patricia Arias Duque ha scritto: Hello . I am trying to refine birnessite type layered manganese oxides and I want to know how can I identify stacking faults on this type of materials?. Thank you in advance for your information, Best Regards and Merry Christmas Nayda Patricia Arias Duque PhD Candidate in Chemical Engineering Nanostructured and Functional Materials Laboratory National University of Colombia- Manizales Campus www.unal.edu.co [1] Links: -- [1] http://www.unal.edu.co ++ Please do NOT attach files to the whole list Send commands to 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 Send commands to 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: Refinement of spiral magnetic structure from neutron powder diffraction
Hi Andrew, A word on GSAS vs Fullprof: GSAS can only handle a magnetic structure that can be defined by a unit cell. So, your incommensurate structure would need to be close to a lock-in value to work, i.e. (0 0 0.32) is close to (0 0 1/3). While it is a lot easier to use a super cell, the peak positions don't line up. In this gratuitous self citation: "High-resolution powder neutron diffraction study of helimagnetic order in CrP1-xVxO4 solid solutions" J. P. Wright, J. P. Attfield, W. I. F. David, and J. B. Forsyth Phys. Rev. B 62, 992 (2000) ... there is an example of a (~1/3,0,0) that didn't lock in. The conclusion was that the student could not avoid learning to use a program that has propagation vectors ;-) Cheers, Jon
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear All We are sorting out Alex's problems off-list but as he is raising many useful points, I'll post a summary of our fixes later. Jon has raised an important point that I thought it worth highlighting- incommensurate structures are not always just P-1. Magnetic structures are Bloch waves and translate through the crystal with sine and cosine dependencies. Whether these waves have inversion symmetry depends on where their origins are... The space group of a magnetic structure is a whole other discussion! Cheers Andrew On 23 Jul 2009, at 18:19, Jon Wright wrote: Dear Alexander, This is theoretically one of the few things that can be done with PRODD, which is a refinement program based on the CCSL subroutine library. Some multibank spiral structure refinements were done with the program when I was doing my thesis. 1) How do I decide on the space group? With incommensurate structures is it always just P -1 I don't think it is always P-1. With CCSL you either have symmetry elements as part of the magnetic symmetry, or not, called MSYM or NSYM. It was rather difficult to figure out. 5) Atom types: Where in the manual do I find the correct types I have to use? Is it always just M in front of the atom? With CCSL you look up the magnetic form factors and put them in the input file with whatever names you like :-) Sorry I can't help much on the fullprof questions. Since you seem to have a multi-k structure, for PRODD you would need at least two phases to do that. I remember spending some time trying with fullprof but eventually learned a valuable lesson about why source code is useful. If you like, I'd be happy to send you the PRODD sources and try to dig out some examples. Even better, you could tidy the sources up and merge them with the current CCSL, realistically I am never going to find the time to do it myself. Spiral magnetic structures are a fantastic way to learn about crystallography and reciprocal space. Good luck! Jon
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear Alexander, This is theoretically one of the few things that can be done with PRODD, which is a refinement program based on the CCSL subroutine library. Some multibank spiral structure refinements were done with the program when I was doing my thesis. 1) How do I decide on the space group? With incommensurate structures is it always just P -1 I don't think it is always P-1. With CCSL you either have symmetry elements as part of the magnetic symmetry, or not, called MSYM or NSYM. It was rather difficult to figure out. 5) Atom types: Where in the manual do I find the correct types I have to use? Is it always just M in front of the atom? With CCSL you look up the magnetic form factors and put them in the input file with whatever names you like :-) Sorry I can't help much on the fullprof questions. Since you seem to have a multi-k structure, for PRODD you would need at least two phases to do that. I remember spending some time trying with fullprof but eventually learned a valuable lesson about why source code is useful. If you like, I'd be happy to send you the PRODD sources and try to dig out some examples. Even better, you could tidy the sources up and merge them with the current CCSL, realistically I am never going to find the time to do it myself. Spiral magnetic structures are a fantastic way to learn about crystallography and reciprocal space. Good luck! Jon
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear Andrew, First, thank you very much for taking the time for this really detailed and helpful answer. It is very much appreciated and I hope that I can give some useful feedback besides consuming your time. Just to let you know, I run everything in vmware fusion on a mac (but it should be exactly the same as native Windows). When I installed SARAh a desktop icon was created that launched SARAh-refine but I didn't 'know anything' of SARAh-representational analysis.That's fine because a beginner would click on the video tutorial button immediately. This however doesn't do anything in my version (7.1.3). I guess it should open a browser and go to the some webpage. Anyway, that's just a minor detail and I figured out that going to ftp://ftp.bcc.ac.uk/pub/users/uccaawi/ has all the tutorials. They are really excellent and I could easily understand how all individual parts of the software are used (of course the underlying representational analysis much less so)! Since we suspect from earlier neutron powder diffraction that the magn structure is incomm I decided to work with Fullprof. So off I went and created the MAT file with Pnma as the underlying crystal structure, one Mn atom in a Wyckoff 4c position (for simplicity I neglected Co moments) and a 'guess' (or rather a value from literature) for k (0 0 tau). The creation of the files was smooth and I was able to load the MAT file in SARAh-refine. For a simple start I selected all the basis functions with the common IR gama(1) and created the pcr file. As the next step I copied the relevant information from sarah62.pcr into my.pcr . Please note that the 'phase header' is slightly different in my pcr because ultimately I want to refine multi-bank patterns from GEM. Therefore some parameters (such as Irf Npr Jtyp Pr1Pr2Pr3 ) are defined individually for each bank on a separate line. I don't know if that's crucial for describing my problem but I thought I'll mention it. The rest of the magnetic phase information was, however, copied from sarah62.pcr as a second phase into my.pcr. For a start I fixed all parameters except the C coefficients (set the value to 1.00 and the code to 1.00) as explained in the tutorial. Running Fullprof results in some pattern calculation BUT unfortunately the scale factor is off so much that the magnetic phase is a factor 10 more intense than the nuclear phase. Refining the scale factor (either for the magn phase or the nuc phase) doesn't help. Neither does setting it to some fixed large value to compensate the scaling difference. I was wondering whether this is a known problem or whether you'd have any guesses as to what I might be doing wrong. If you want to see any files please let me know. I'm more than happy to send them. The possibility to solve a magnetic structure from basic principles such as group theory and RA seems very appealing and unbiased to me so I hope that there is a solution to problems arising on the way. Once again I'm very grateful for your help and time. Alex 2009/7/23 Andrew Wills > Dear Alex > The MAT file is generated from the symmetry analysis calculations using > SARAh-Representational Analysis (there are video help files to show you how > to do this). > > If you are setting up a refinement in GSAS, you can use SARAh Refine to > set up the magnetic phase for you. There are 2 options: > > 1) you set up the phase, make it magnetic and put in an atom with a moment > on it to make sure it works. Select /Insert magnetic atoms , > to overwrite this atom with all the atoms for your P1 magnetic structure. > (this is required so that SARAh can match the atom to its moment > orientation > > 2) Use SARAh Refine to set up the magnetic phase for you. > -To do this, delete all the atoms in the P1 phase, then delete the phase > itself. Run Powpref to make sure it works. > -Then Select /Make magnetic phase (Fully automatic) > -Define the nuclear phase that will be used as a template for the magnetic > phase's lattice parameters, profile, etc > -Define the form factors of the different moments > > -The phase will now be set up for you. (If there are problems with this, > let me know and I'll try to fix them) > > Refining the structure is then based on selecting the basis vectors and > firing off reverse-Monte Carlo cycles. There is no need to define red/black > symmetries in GSAS as the moment orientations are all looked after by SARAh. > Start with selecting the basis vectors of a single irreducible > representation, and then combining them if that fails to fit your data. It > is important to learn to read basis vectors and what they correspond to- > SARAh has some help files to help you get to grips with this. > > A word on GSAS vs Fullprof: > GSAS can only handle a magnetic structure that can be defined by a unit > cell. So, your incommensurate structure would need to be close to a lock-in > value to work, i.e. (0 0 0.32) is close to (0 0 > 1/3). That said, the definition of the
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear Alex The MAT file is generated from the symmetry analysis calculations using SARAh-Representational Analysis (there are video help files to show you how to do this). If you are setting up a refinement in GSAS, you can use SARAh Refine to set up the magnetic phase for you. There are 2 options: 1) you set up the phase, make it magnetic and put in an atom with a moment on it to make sure it works. Select /Insert magnetic atoms , to overwrite this atom with all the atoms for your P1 magnetic structure. (this is required so that SARAh can match the atom to its moment orientation 2) Use SARAh Refine to set up the magnetic phase for you. -To do this, delete all the atoms in the P1 phase, then delete the phase itself. Run Powpref to make sure it works. -Then Select /Make magnetic phase (Fully automatic) -Define the nuclear phase that will be used as a template for the magnetic phase's lattice parameters, profile, etc -Define the form factors of the different moments -The phase will now be set up for you. (If there are problems with this, let me know and I'll try to fix them) Refining the structure is then based on selecting the basis vectors and firing off reverse-Monte Carlo cycles. There is no need to define red/black symmetries in GSAS as the moment orientations are all looked after by SARAh. Start with selecting the basis vectors of a single irreducible representation, and then combining them if that fails to fit your data. It is important to learn to read basis vectors and what they correspond to- SARAh has some help files to help you get to grips with this. A word on GSAS vs Fullprof: GSAS can only handle a magnetic structure that can be defined by a unit cell. So, your incommensurate structure would need to be close to a lock-in value to work, i.e. (0 0 0.32) is close to (0 0 1/3). That said, the definition of the magnetic structure can be very simple, a set of moments in P1, so setting understanding what it all means is quite unambiguous. FullProf has a k vector and is far more flexible in the ways in which magnetic structures can be defined. This flexibility can make it hard to set up a magnetic phase. SARAh -Refine tries to deal with most of these problems for you (see the video help for the entire process), but it is sometimes less obvious to see what is happening in the pcr file. If you have any questions, feel free to get in contact. Good luck! Andrew ps/ to see the SARAh documentation- install SARAh (which contains SARAh-Representational Analysis and SARAh-Refine) on a windows computer (including macs with parallels or vmfusion), and look in the help menu On 23 Jul 2009, at 12:27, Alexander Barcza wrote: Dear Ross, Thanks for your reply. Sorry for being so exclusive in my initail mail, of course I should have included everyone! The title of PhD student also applies to me. I've seen a talk about SARAh by Andrew Wills at ISIS and was impressed by it. Therefore I've already downloaded it but didn't succeed in using it yet. The problem is actually already at the beginning: In my GSAS file I created a second phase with P1 and just copied the atoms of the main phase over. I loaded that file by clicking , How do I then define the MAT file? Sorry, it must be obvious but I can't find it. I am happy to read some documentation but couldn't find any on the website (http://www.chem.ucl.ac.uk/people/wills/index.html ). Thanks again for your help Alex 2009/7/23 Ross H Colman Dear Alex, You addressed your email to "experts on magnetic refinement" so I apologise if I am the only person to reply for I am a lowly PhD student. I am afraid I am not going to answer your questions directly but instead point you to the program that I use for magnetic refinements. Its free software available on CCP14 called SARAh. It allows you to input your magnetic atom sites, space group and k-vector then has the ability to modify your fullprof pcr file depending on how you wish to do the refinement. The process is a little involved, as it uses representational theory to reduce your problem to symmetry allowed structures, rather than freely refining all variables, but it has step by step instructions and I think there are even some online help videos for using it now. Available from: www.CCP14.ac.uk or www.chem.ucl.ac.uk/people/wills/index.html Best regards and good luck Ross Colman > Dear experts on magnetic refinement, > > We recently got some nice data on GEM, ISIS and I was able to get a decent > structural fit using GSAS and FullProf. > > Now I would like to refine the magnetic structure but this is my first > time > so I struggle to give FullProf what it wants. > > Since I'm a novice treating the magnetic data I'd have some general > questions about the input (which I attached below). The general structure > of > the pcr file seems to be OK, because it is read by FP but unfortunately
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear Ross, Thanks for your reply. Sorry for being so exclusive in my initail mail, of course I should have included everyone! The title of PhD student also applies to me. I've seen a talk about SARAh by Andrew Wills at ISIS and was impressed by it. Therefore I've already downloaded it but didn't succeed in using it yet. The problem is actually already at the beginning: In my GSAS file I created a second phase with P1 and just copied the atoms of the main phase over. I loaded that file by clicking , How do I then define the MAT file? Sorry, it must be obvious but I can't find it. I am happy to read some documentation but couldn't find any on the website ( http://www.chem.ucl.ac.uk/people/wills/index.html). Thanks again for your help Alex 2009/7/23 Ross H Colman > Dear Alex, > > You addressed your email to "experts on magnetic refinement" so I > apologise if I am the only person to reply for I am a lowly PhD student. > > I am afraid I am not going to answer your questions directly but instead > point you to the program that I use for magnetic refinements. Its free > software available on CCP14 called SARAh. It allows you to input your > magnetic atom sites, space group and k-vector then has the ability to > modify your fullprof pcr file depending on how you wish to do the > refinement. > > The process is a little involved, as it uses representational theory to > reduce your problem to symmetry allowed structures, rather than freely > refining all variables, but it has step by step instructions and I think > there are even some online help videos for using it now. > > Available from: > www.CCP14.ac.uk or > www.chem.ucl.ac.uk/people/wills/index.html > > Best regards and good luck > Ross Colman > > > > Dear experts on magnetic refinement, > > > > We recently got some nice data on GEM, ISIS and I was able to get a > decent > > structural fit using GSAS and FullProf. > > > > Now I would like to refine the magnetic structure but this is my first > > time > > so I struggle to give FullProf what it wants. > > > > Since I'm a novice treating the magnetic data I'd have some general > > questions about the input (which I attached below). The general structure > > of > > the pcr file seems to be OK, because it is read by FP but unfortunately > in > > the current form leads to a singular matrix. I'm sure I've done something > > wrong with the input parameters. > > > > Here is a quick outline of what I want to achieve: > > There are two magnetic ions in the structure. Mn and Co, but Co has a > very > > small moment (we know that from neutron diffraction from the 80's). The > > moments seem to order in two incommensurate spiral structures (one for Mn > > and one for Co) with the k-vector along c-axis. I thought it is best to > > include a separate purely magnetic phase in FP. Would you agree and if > yes > > can I still do a multi-bank refinenment? > > > > Here is the snippet from the pcr file which was inspired by Ho2Cu2O5, an > > example from the FP webpage (questions below): > > > -- > > CoMnSi(magnetic > > reflection) > > > > ! > > !Nat Dis Mom Jbt Isy Str FurthATZ Nvk More > >2 0 0 -1-1 0 0 0. 2 1 > > !Jvi Jdi Hel Sol Mom Ter > > 3 0 0 0 0 0 > > !Contributions (0/1) of this phase to the 6 patterns (FOR simplicity I > > deleted all but the first pattern to get started) > > 1 > > !Irf Npr Jtyp Nsp_Ref Ph_Shift for Pattern# 1 > > -1 13 -1 0 0 > > ! Pr1Pr2Pr3 Brind. Rmua Rmub Rmuc for Pattern# 1 > > 0.000 0.000 1.000 1.000 0.000 0.000 0.000 > > P -1 <--Space group symbol > > !Nsym Cen Laue MagMat > >4 1 31 > > ! > > SYMM x,y,z > > MSYM u,v,w,0.0 > > SYMM -x,-y,z+1/2 > > MSYM u, v,-w,0.0 > > SYMM x+1/2,-y+1/2,z > > MSYM -u,v,-w,0.0 > > SYMM -x+1/2,y+1/2,z+1/2 > > MSYM u,-v,-w,0.0 > > ! > > !Atom Typ Mag VekXYZ Biso Occ Rm > > Rphi Rtheta > > ! Im Iphi Ithetabeta11 beta22 beta33 MagPh > > Co1 MCO2 1 1 0.15609 0.25000 0.05324 0.0 1.0 > > 0.323.0 > > 45.0 > > > > 220.00 0.00 230.00 280.00 0.00 0.0 > > 0.0 0.0 > > 0.0 0.0 0.0 0.0 0.0 0.0 > > 0.00 0.00 0.00 0.00 0.00 0.00 > > Mn1 MMN2 1 2 0.02093 0.25000 0.68070 0.0 1.0 > > 3.1 178.0 > > 13.0 > > > > 0.00 0.00 0.00 0.00 0.00 > > 0.0 0.0 0.0 > > 0.0 0.0 0.0 0.0 0.0 0.0 > > 0.00 0.00 0.00 0.00 0.00 0.00 > > !---> Profile Parameters for Pattern # 1 > > ! Scale Extinc Bov Str1 Str2 Str3Strain-Model > >
Re: Refinement of spiral magnetic structure from neutron powder diffraction
Dear Alex, You addressed your email to "experts on magnetic refinement" so I apologise if I am the only person to reply for I am a lowly PhD student. I am afraid I am not going to answer your questions directly but instead point you to the program that I use for magnetic refinements. Its free software available on CCP14 called SARAh. It allows you to input your magnetic atom sites, space group and k-vector then has the ability to modify your fullprof pcr file depending on how you wish to do the refinement. The process is a little involved, as it uses representational theory to reduce your problem to symmetry allowed structures, rather than freely refining all variables, but it has step by step instructions and I think there are even some online help videos for using it now. Available from: www.CCP14.ac.uk or www.chem.ucl.ac.uk/people/wills/index.html Best regards and good luck Ross Colman > Dear experts on magnetic refinement, > > We recently got some nice data on GEM, ISIS and I was able to get a decent > structural fit using GSAS and FullProf. > > Now I would like to refine the magnetic structure but this is my first > time > so I struggle to give FullProf what it wants. > > Since I'm a novice treating the magnetic data I'd have some general > questions about the input (which I attached below). The general structure > of > the pcr file seems to be OK, because it is read by FP but unfortunately in > the current form leads to a singular matrix. I'm sure I've done something > wrong with the input parameters. > > Here is a quick outline of what I want to achieve: > There are two magnetic ions in the structure. Mn and Co, but Co has a very > small moment (we know that from neutron diffraction from the 80's). The > moments seem to order in two incommensurate spiral structures (one for Mn > and one for Co) with the k-vector along c-axis. I thought it is best to > include a separate purely magnetic phase in FP. Would you agree and if yes > can I still do a multi-bank refinenment? > > Here is the snippet from the pcr file which was inspired by Ho2Cu2O5, an > example from the FP webpage (questions below): > -- > CoMnSi(magnetic > reflection) > > ! > !Nat Dis Mom Jbt Isy Str FurthATZ Nvk More >2 0 0 -1-1 0 0 0. 2 1 > !Jvi Jdi Hel Sol Mom Ter > 3 0 0 0 0 0 > !Contributions (0/1) of this phase to the 6 patterns (FOR simplicity I > deleted all but the first pattern to get started) > 1 > !Irf Npr Jtyp Nsp_Ref Ph_Shift for Pattern# 1 > -1 13 -1 0 0 > ! Pr1Pr2Pr3 Brind. Rmua Rmub Rmuc for Pattern# 1 > 0.000 0.000 1.000 1.000 0.000 0.000 0.000 > P -1 <--Space group symbol > !Nsym Cen Laue MagMat >4 1 31 > ! > SYMM x,y,z > MSYM u,v,w,0.0 > SYMM -x,-y,z+1/2 > MSYM u, v,-w,0.0 > SYMM x+1/2,-y+1/2,z > MSYM -u,v,-w,0.0 > SYMM -x+1/2,y+1/2,z+1/2 > MSYM u,-v,-w,0.0 > ! > !Atom Typ Mag VekXYZ Biso Occ Rm > Rphi Rtheta > ! Im Iphi Ithetabeta11 beta22 beta33 MagPh > Co1 MCO2 1 1 0.15609 0.25000 0.05324 0.0 1.0 > 0.323.0 > 45.0 > > 220.00 0.00 230.00 280.00 0.00 0.0 > 0.0 0.0 > 0.0 0.0 0.0 0.0 0.0 0.0 > 0.00 0.00 0.00 0.00 0.00 0.00 > Mn1 MMN2 1 2 0.02093 0.25000 0.68070 0.0 1.0 > 3.1 178.0 > 13.0 > > 0.00 0.00 0.00 0.00 0.00 > 0.0 0.0 0.0 > 0.0 0.0 0.0 0.0 0.0 0.0 > 0.00 0.00 0.00 0.00 0.00 0.00 > !---> Profile Parameters for Pattern # 1 > ! Scale Extinc Bov Str1 Str2 Str3Strain-Model > 4.8798 0. 0. 0. 0. 0. 0 > 1.0 0.00 0.00 0.00 0.00 0.00 > ! Sig-2 Sig-1 Sig-0Xt Yt Z1 > Z0 Size-Model > ! 0.000186.666 0.000 <- Instr. par. + shifts. Only shifts are > refined > 0.000 33.363 0.000 0.000 0.000 0.000 > 0.000 0 > 350.00 31.00 0.00 0.00 0.00 0.00 > 0.00 > !Gam-2 Gam-1 Gam-0 LStr LSiz > !0.000 0.000 0.000 <- Instr. par. + shifts. Only shifts are > refined > 0.000 0.000 0.000 0.000 0.000 > 0.00 0.00 0.00 0.00 0.00 > ! a b calpha beta gamma #Cell > Info >5.866537 3.692333 6.856417 90.00 90.00 > 90.00 > >0.00.00.00.00.00.0 > ! Pref1 Pref2alph0 beta0 alph1
Re: Refinement of LSMO particles
>I don't know how to generate a proper PCR file of the (La,Sr)MnO3 crystalline >powder There are full instructions and examples of FullProf PCR files on our server: http://www.ill.fr/dif/Soft/fp/ In particular http://www.ill.fr/dif/Soft/fp/downloads/Docs/pcr_dat.zip contains a PCR file for LaMnO3 Alan. _ Dr Alan Hewat, ILL Grenoble, FRANCE<[EMAIL PROTECTED]>fax+33.476.20.76.48 +33.476.20.72.13 (.26 Mme Guillermet) http://www.ill.fr/dif/people/hewat/ _
Re: Refinement result
I had something similar to this years ago. It was going after applying the preferred orientation factor and an axial displacement. jilin zhang On Jul 16, 2004, at 9:10 PM, Riza Iskandar wrote: Dear colleagues, Can anyone help me to interpretation my refinement results? Why my residual curve still high, even my calculated curve already fitted with my experiment curve. Is it because there are another phase occur in the same position? I look forward for your guidance. Riza Iskandar Research Center for Materials Science University of Indonesia
Re: Refinement of Valentinite (orthorhombic Sb2O3)
Thanks very much. This structure matched my data quite well.
Re: Refinement of Valentinite (orthorhombic Sb2O3)
>I'm trying to do a refinement on Valentinite. However, when I use the unit >cell data from the ICSD demo server (http://barns.ill.fr/dif/icsd/index.html) >I get very different relative intensities than what I observe in my powder >pattern, and that of the ICDD pattern (11-689 generated by the NBS). There are more recent determinations of the structure of orthorhombic Sb2O3 in the full ICSD. Svensson,C. (1974) Acta Crystallogr.,Sect. 30 458-461 The crystal structure of orthorhombic antimony trioxide, Sb2 O3 cf: Buerger,MJ. (1936) Am.Miner 21 206-207 The crystal structure of valentinite In particular you might try orthorhombic Sb2O3 as determined by Svensson(1974), which has the same Pccn space group as that of Buerger(1936) but with different coordinates. (Svensson,C. (1975) Acta Cryst. 31 2016-2018 also reports on the cubic phase). N *-Sb2O3-Svensson C 30 (1974) P. 458-461 C 4.911 12.464 5.412 90. 90. 90. S GRUP P C C N A Sb10.04149 0.12745 0.17845 0.0 1.0 A O1 0.25000 0.25000 0.02290 0.0 1.0 A O2 0.15200 0.05910 0.85540 0.0 1.0 N *Valentinite-Sb2O3-Buerger M J 21 (1936) P. 206-2 C 4.92 12.46 5.42 90. 90. 90. S GRUP P C C N A Sb10.12150 0.20700 0.17500 0.0 1.0 A O1 0.25000 0.25000 0.92500 0.0 1.0 A O2 0.89000 0.15600 0.17500 0.0 1.0 There was also a (relatively minor) error in the ICSD-for-WWW pattern calculation where the occupations and temperature factors were mixed up (corrected yesterday thanks to Colin Greaves) so you should also repeat that calculation. >The Lazy PulverIx data file gives this warning when calculating the pattern: > Crystal system specified on CELL card and on GROUP card are not consistent It always gives that message, and you can ignore it :-) Alan Hewat, ILL Grenoble, FRANCE <[EMAIL PROTECTED]> tel (33) 4.76.20.72.13 ftp://ftp.ill.fr/pub/dif fax (33) 4.76.20.76.48 http://www.ill.fr/dif/
Re: Refinement with more than two atoms in one site
Dear kasthuri Please read the following and recent discussion. Good luck Jaap On Thu, 14 Jan 1999, Jean-Marc Joubert wrote: > > > >> Could any of you point me to the good document about the method of applying > >> constraints in GSAS? > >> I am trying to figure out some complex cationic intermixing in a layered > >> cuprate superlatttice compound. > >> But I couldn't find a good documentation in the manual. Specially trouble > >> with a constraint with >2 variables. > >> For example, how do you make a constraint for something like x+2y+2z=1. > >> Thanks for your help. > > >In a few words -- you probably can't do that with GSAS. This is not true > >of all Rietveld codes, but in GSAS a variable parameter can only appear > >in one constraint equation. One option that might help would be to put a > >soft constraint on the total composition. > > > > Yes you can. You have to use a trick which is detailed in (J.-M. Joubert et > al., J. Appl. Crystalogr. 31 (1998) 327-332). > If you have three atoms on the same site and want to refine occupancy > factors (theoretically it is only possible if you have two data sets, for > example X-ray and neutrons), you have to introduce a fourth fictive atom : > > You have, for example : > Atom 1, Ni, occupancy x > Atom 2, Mn, occupancy y > Atom 3, Co, occupancy z > and wants to constrain x+2y+2z=1 > > You introduce : > Atom 4, Ni, occupancy u > and change occupancy of atom 1 to v in such a way that u+v=x > Set the constraints on the parameters shifts : > du=-2dy > dv=-2dz > You will maintain by this way the condition u+v+2y+2z=x+2y+2z=1 > > Regards. > > Jean-Marc Joubert > > --- > Jean-Marc Joubert > Laboratoire de Chimie Metallurgique des Terres Rares > CNRS - UPR 209 > 2-8 rue Henri DUNANT, > 94320 THIAIS CEDEX - FRANCE > > Phone:33 (0)1 49 78 12 11 > Fax: 33 (0)1 49 78 12 03 > > Email:[EMAIL PROTECTED] > Jaap Vente Cinvestav-IPN Unidad Merida Departamento de Fisica Aplicada Carretera Ant. a Progreso km 6 Apartado Postal #73 Cordemex Merida, Yucatan, 97310 Mexico Fax: (..) 52 - 99 - 812917 Tel: (..) 52 - 99 - 812960 ext 246/233 e-mail: [EMAIL PROTECTED]
Re: Refinement by BGMN
At 13:25 29.01.99 +0100, Angel Luis wrote: >Dear all > >I am working with a Philips PW-1800 diffractometer and I want to do >Rietveld's refinament by BGMN code. > >I need some variables of it; as goniometer radius, height and width >of the X-ray tube´s focus, radius and width of the horizontal divergence >slit, divergence angle of the primary collimator, radius and width of the >vertical divergence slit, divergence angle of the secondary collimator, >width and height of the detector slit, radius of a secondary monochromator > Hi, Angel Luis, here is a pw1800.sav for calculation the device profile by GEOMET and MAKEGEQ. Please look at the comments. You must check especially the detector (receiving) slit used and the tube (focus dimensions). The optical focus width of standard fine and long fine focus tubes is 0.04mm, a 10th of the specified thermal focus width, in the case of 6° take off angle. Not shure about the standard PW1800 tube type. Best Reinhard % Titel of Calculation TITEL=PW_1800_16mm_Sample GEOMETRY=REFLEXION % Name of 'Raytraced' Goniometer Function VERZERR=pw1800.ger % Name of Interpolated Goniometer Function GEQ=pw1800.geq % Helper Variables pi=2*acos(0) % Rowland Circle Radius R=173 % Estimated 1/mue (mm), should be set to the actual sample value D=0.1 % Sample thickness (mm) T=2.5 % Divergence Slit Position (Distance from goniometer axis, here 87 is the distance from focus to ADS axis) HSlitR=173-87 % Automatic Divergence Slit opening formula (10 is the const. irradiated length) HSlitW=(2*87*10*sin(pi*zweiTheta/360))/(2*173+10*cos(pi*zweiTheta/360)) % Secondary Monochromator Position MonR=173+59 % Tube Focus Length (mm), please check the type, here long fine focus FocusH=12 % Optical Focus Width (mm), please check the type, here fine focus FocusW=0.04 % Detector Slit Heigth (mm), normally the heigth of the graphite crystal DetH=15 % Detector Slit Width (mm) DetW=0.1 % Sample Diameter (mm) SamplD=16 % Primary and Secondary Collimator (Width/Length) PColl=0.61/20 SColl=0.61/20 % 2Theta List for GEOMET zweiTheta[1]=6 zweiTheta[2]=10 zweiTheta[3]=16 zweiTheta[4]=24 zweiTheta[5]=34 zweiTheta[6]=48 zweiTheta[7]=60 zweiTheta[8]=90 zweiTheta[9]=120 zweiTheta[10]=150 % Angle Range for MAKEGEQ WMIN=6 WMAX=150 WSTEP=2*sin(pi*zweiTheta/180) % Intensity Modelling, necessary for ADS, beam overflow, capillary, transmission GSUM=Y
Re: Refinement of polymers
On Tue, 5 Jan 1999 14:15:38 -0300 (GRNLNDST), Erica Goncalves Gravina - ig wrote: >Hi every one! >My name is Erica and I am a Chemistry student at the University of >Brasilia, Brazil. I am still doing my graduation and I've been working >with the refinement of minerals since 1996 but this year I started a new >project with polymers so, I decided as soon as possible do the refinement >of polymers structure. >So talking to my tutor he said that is not commum a refinement of this >materials using the Rietveld method so what I would like to know from you >is some papers and works whith this subject that already exist. >If someone can help me I will be very glad. >Thank you >Miss Gravina > > > > >My e-mail : [EMAIL PROTECTED] > Hi Erica! Peter Friedel has done (and still does) Rietveld refinements of polymers. He works at the Institute for Polymer Research here in Dresden, Germany. Please, visit our BGMN home page at http://www.bgmn.de You will find links to -Peter Friedels pages explaining how our Rietveld Refinements of polymers work. Of course, Peter Friedel gives a list of his publications. -my personal homepage, which includes a list of our actual publications. Some of them fit the area of polymers Rietveld refinement. Good luck! Joerg Bergmann [EMAIL PROTECTED]
Re: Refinement of polymers
see Schwartz and Von Dreele, Advances in X-Ray Analysis, Vol. 39, pp 515-521 (1997) for a full Rietveld structure refinement of high density polyethylene using laboratory XRD data collected with a Siemens D500 with a 1D PSD and an incident beam quartz monochromator. Send me your mailing address and I will send you a reprint. Ken Schwartz [EMAIL PROTECTED] ___ Subject: Refinement of polymers From:RIETVELD_L Distribution List <[EMAIL PROTECTED]> at internet Date:1/5/99 2:15 PM Hi every one! My name is Erica and I am a Chemistry student at the University of Brasilia, Brazil. I am still doing my graduation and I've been working with the refinement of minerals since 1996 but this year I started a new project with polymers so, I decided as soon as possible do the refinement of polymers structure. So talking to my tutor he said that is not commum a refinement of this materials using the Rietveld method so what I would like to know from you is some papers and works whith this subject that already exist. If someone can help me I will be very glad. Thank you Miss Gravina My e-mail : [EMAIL PROTECTED]
