thank you for this very useful video! you can get the weight fraction direct from the window where you refine the phase fraction, just at the side of the phase fraction box. regards
Hi Professor, I have a question regarding the instrument parameter file. In the beginning of the video you mention that a calibration with a standard reference should be performed before starting the Rietveld refinement. For context, I am working with 2d XRD data from a standard CeO2 reference that I collected at a synchrotron facility. The first step I did was to calibrate the 2d rings with one of the standards listed in GSAS, thus correcting sample-detector distance, rotation, etc.. I then integrated the data to get an I-2theta line plot. At this point I performed a refinement with a .CIF file for CeO2, from which I found all the instr. parameters for both Gaussian and Lorentzian components down to a Rwp of ~4%--I then saved these instr. parameter values. Now moving on to an actual sample, I thought that in order to get a reliable reading of peak width (fwhm), peak broadening from instrumental broadening should be taken into consideration, and I assumed this is what the instr. parameter file created from the CeO2 reference would be used for. In other words, I assumed that by copy/pasting the instrument parameters (UVWXYZ) obtained from the CeO2 reference sample onto the data from a different sample would effectively "adjust" for problems such as instr. peak broadening. I was hoping you could point out any flaws in my logic and/or explain why later on in the video you refine the instr. parameters for your sample even though you already imported instr. parameters from a known reference. i.e: Once the Instr. parameters from the reference are found, why do they need to be further refined? Wouldn't doing so give a misleading peak width/shape reading? Did I misunderstand something in the steps you showed? Forgive me for the painfully long comment--your time and help are greatly appreciated. Best, Alex
Good question and one that I had before as well. Technically, you are correct. The refinement from the instrument parameter should give you the peak shape that comes from the instrument meaning that any additional change the shape comes from the sample itself. Therefore, you should hold U,V,W constant and only adjust LX and LY. However, in practice, almost nobody does this.
Sir, How to make an output file for the electron density mapping from GSAS II refinement? For example in GSAS I, it can create the .grd and .fob files for the mapping.
In "Import phase", refining multiple patterns, You said we had to make sure all experimental conditions are same. "All experimental conditions" are the conditions we measure to collect XRD histograms, aren't they?
@@ThangPVan_ technically yes. But common and if amount of impurities is small then impact is small. Gold standard approach is to add a known wt fraction of a standard like Si or Al2O3 and then you can calculate true amounts even if amorphous phase is present
yeah, the ROR method can calculate the true amounts of amorphous phases. But it's quite inconvenient when we had too many samples to refine @@TaylorSparks
subversion.xray.aps.anl.gov/pyGSAS/Tutorials/CWInstDemo/FindProfParamCW.htm I can send you a file with the different regions of the file explained if needed. email me
Really nice video. I have a question for exporting the calculation fitting data, how to export and load to such as OriginPro to reveal the original and fitting data. Many thanks for your time.
After spending so much time on refinement of my pattern, I got dialogue box saying"Error Refinement failed" how to resolve this.. do I have to repeat it? Pls help Mr.Taylor
Currently, I am working on XRD refinement Unfortunately, I struggled a lot during the refinement process. Because I am adding new elements with the existing crystal system and convert to another phase or mixed phase. In this case, please explain "How to change the crystal phase and do refinement?" or how to optimize or find a new crystal phase after doping?. I hope, you understand my question. Please help to solve our problem. thanks in advance
Hi your tutorial was very informative but I’m struggling to understand how much of the UVWXY parameters I should refine. Refining them individually one time each gives some good values above 0 and usually under 1, but if I keep refining them the values approach 0 or diverge to large positive values, suggesting a local minimum rather than global minimum was reached. How is this explained? Also how is X and Y different from the crystallite size and micro strain parameters under the phase/data tab, since they seem to correlate a lot? This step is crucial as it influences the extent of subsequent refinement, so I’d appreciate any suggestions.
typically think of UVWXY as just tools to get the right shape. So there aren't "right" values, per se. I typically do the one at a time then I start getting multiple at a time. XY differ from UVW because they give Lorentzian shape as opposed to a gaussian. Some refinements use these synonymously with crystal size/strain. However, that would be wrong because size and strain are phase-dependent whereas XY are global. You want to refine strain/size on a per-phase basis, not globally.
Thanks! Also do you happen to know how to refine anisotropic crystallite size parameters and whether I can check them against SEM images? Do I refine each parameter independently then together?
@@oliverwang4670 unfortunately I don't know how to do that. I've had some limited experiencing modeling overall powder patterns that are textured where you need to use anisotropic texturing factors but I don't think I'm an expert there.
while downloading the cif files from materials project, I found that the primitive cell is a Triclinic P1 structure (for all crystals). How to convert this triclinic P1-primitive cell to the original symmetrized unit cell? and/or how to find the original crystal system from this primitive cell (triclinic P1) Is there any calculation or software is available? In my case, the XRD pattern was changed to another unknown phase after doping. How to solve my problem. Please explain this. Thanks in advance
@@TaylorSparks Dear Sir, Thank you very much for the reply, Actually I have another problem. Currently, I am working on XRD refinement Unfortunately, I struggled a lot during the refinement process. Because I am adding new elements with the existing crystal system and convert to another phase or mixed phase. In this case, please explain "How to change the crystal phase and do refinement?" or how to optimize or find a new crystal phase after doping?. I hope, you understand my question. Please help to solve our problem. thanks in advance
Hello. I did refinement using GSAS II. However, when I tried to change the color of my plot, it did not change anything. I took my file to run it on my colleague`s computer. This does not happen. Please advise which is the reason causing my color change problem?
Perhaps the easiest way is to export the CIF file, open it in VESTA and use their bond tool to show the bond. Are you familiar with CIF files and Vesta? It's quite easy to do but I can show you in another video of needed.
Sorry! I should have mentioned that I am using GSAS EXPGUI. GSASII seems much better. I tried to install it but I couldn't find the software for 32-bit Windows. Is there still a way to export CIF file and do the rest with VESTA?
Thank you so much for this great video. I have a question about the instrument parameter file I can't understand this subject (my XRD sample is (NaYF4:Yb, Er)). I used Highscore Expert software to check out the best fit of my sample. May I consider the best match as a reference file and put it as an instrument parameter? moreover, the only way I can extract the file from the expert is PDF or TXT file how can I apply it in GSAS format. I do appreciate it if you help me with this issue.
Hello Sir , I am new to GSAS 2 and would like to have a few things clarified regarding the same. What parameters you need to refine to improve the intensity of a XRD peaks. For my sample for few peaks the intensity is not matching. Also for solid solutions between two phase, whether we need to refine for both phase or for the host phase excluding the substituted phase. Thank you Hope I was able to clarify my doubt s.
we talk about that in this video. It depends on many things. Some of the common ones are atomic fractional occupancy, atom per site, and thermal displacement parameters.
Sir, If we have a solid solution between Compounds A and B, with A having 10 moles of B substituted within. Do we need to refine with both phases. My doubt is since the XRD gives the Crystal structure corresponding to A having a shift in 2 theta due to substitution by compound B. Does the lattice parameter is only needed to be refined? Since I have not peaks corresponding to B.
@@afineethcrazyworld346 okay, if you only see peaks corresponding to the a-phase then I would start by refining the lattice parameter. However, you should also consider looking at mixed occupancy on your sites. This will influence the intensity of your peaks. You can put both atoms on the site and refine their occupancy with the constraint that it adds up to one for example.
Hi ,Taylor, thank you for such an informative video!, But, I have some problems with opening powder data. When I open my own .raw file, the software showed me "its a binary format file" and unable to read it. When I try to use your file, it showed me "unable to read" too. So I wonder if you have similar problems and how to solve it. Thanks a lot.
Hello, Taylor. Excellent and very helpful explanation. I would like to ask if you know any methodology to determine Amorphous Content (or Degree of Crystallinity) of a sample using GSAS-II or MAUD. I can't find it.
Yes, it's possible. You need to mix some crystalline material into your sample with a very specific known weight percent. For example, if you add 10% by weight of silicon and then you do the refinement you can use this to back out calculate what the amorphous fraction should be since the amount of silicon will be less than 10%.
@@TaylorSparks OK, I already have a data of a sample with a known amorphous percentage, I wanted to know how I make GSAS-II refine it correctly. Is it just uncheck Histogram Scale and check Phase Fraction?
Thanks for your great video. I have my xrd data and I have information related to my phases. but I dont know how I have to create my instrument parameter. would you please help me how I can prepare instrument parameter for my data? What I have to do exactly?
Thanks alot for your help. The measurement was determined by X-ray diffraction (XRD; Bruker D8 Focus; Cu Ka radiation). I cant understant what geometry do you mean? do you mean the angles? my email adress is: sakine.khajavi@uqtr.ca
In general, you should probably only report the weight fractions once you have gotten the weighted residual below 10% if you're going to be publishing your findings.
Hi!! Could you please do a video on how to update GSAS 2. No matter how many times I click on "check for update" it never seems to update, or maybe it does but I don't realize it. Thank you!! Your videos are super helpful.
@@TaylorSparks No because to be honest it was kind of a pain to install it in the first place. But if I have to do so later on I might try it. Thank you for checking it and letting me know that my program has the issue!!
Hi!! I just reinstalled it and it’s up to date now. I just hope that this fixed it. If not, then i’ll just have to reinstall it again and again 😭(hopefully not though😂😅)
@@TaylorSparks Hi, sorry to bug you again but even though I had reinstalled it yesterday it still will not update from 4055 version to 4056. I looked at the terminal window of the program and I noticed it had a warning "Warning: failed to import the optimized Py3 pickle (_pickle)." Could that be the issue for why it will not update??
Raghunandan S every instrument that you use should have its own instrument parameter file. If you have a panalytical instrument then I can send you a generic one, but you will need to modify it with your own instrument parameters such as the zero goniometer arm Etc.
what instrument did you measure your data on originally? There are a few different types of .Raw files. It's possible that it saved it as the wrong type. There are lots of diffraction converters though. It should be possible to convert it to the correct type.
Panalytical should have no problem saving your file as a .Raw file. If you are having some trouble it's also possible to convert it using a conversion software such as PowDLL
Hi! Thank you for the video. I have a question though about refining the shape of the peaks. I would like to know the size of the particles of the sample. Does that still give you accurate results from the refinement if you refine the instrument parameters? As those are known and accurate, should not the thermal displacement, relative phase fractions or fractional occupancy be refined for? Thank you
Hi! if you want to determine particle size then you can use the well-known Scherrer formula. To use this formula you need to use the FWHM (full-width at half-max). However, broadening doesn't only come from your samples. You can also get instrumental broadening. Therefore, to correctly use Scherrer formula you should first scan a standard material which will have very sharp peaks. When you do so you'll be able to plot instrumental FWHM as a function of two-theta. Fit a line through this data and use the line to subtract instrumental broadening from your observed XRD scan FWHM so that you can more accurately estimate particle size. To your second question, shouldn't thermal displacement, phase fraction etc be refined. Yes. However, I don't believe those should change your FWHM (assuming peaks don't overlap) since you are reading this directly from observed data, not the fit to the data.
Hey, Thank you for this informative tutorial video. Could you please send me the step by step file? I wish to perform Rietveld refinement on my XRD data having multiple phases. Thanks....
Nice video. Do you know how can I create the .prm file? Or better, do you have a text document or do you know about a tutorial to do it by myself? Thanks in advance!
Carlos, I don't know of a formal text document that details the procedure. However, it is pretty straight-forward. You just open up the prm file in a notepad style editor and change the important bits to match your machine like the X-ray wavelength. You also modify the values for the zero, U, V, and W values for your instrument after you obtain them by scanning and fitting a standard with known lattice parameter. When you download the tutorial files for GSAS you will see several examples of prm files on different instruments.
Thanks for your great video. I have my xrd data and I have information related to my phases. but I dont know how I have to create my instrument parameter. would you please help me how I can prepare instrument parameter for my data? What I have to do exactly? My email address is: sakine.khajavi@uqtr.ca
Hey, you could not set limit in your video because your zoom button on plot window was turned on as shown in the screenshot below, by the way nice video... oi66.tinypic.com/epehw0.jpg
This is such a great video. Thanks a lot for attaching the practice files; it helps us so much to follow through with each step.
thank you for this very useful video! you can get the weight fraction direct from the window where you refine the phase fraction, just at the side of the phase fraction box. regards
thank you!
Hi Professor, I have a question regarding the instrument parameter file.
In the beginning of the video you mention that a calibration with a standard reference should be performed before starting the Rietveld refinement. For context, I am working with 2d XRD data from a standard CeO2 reference that I collected at a synchrotron facility. The first step I did was to calibrate the 2d rings with one of the standards listed in GSAS, thus correcting sample-detector distance, rotation, etc.. I then integrated the data to get an I-2theta line plot.
At this point I performed a refinement with a .CIF file for CeO2, from which I found all the instr. parameters for both Gaussian and Lorentzian components down to a Rwp of ~4%--I then saved these instr. parameter values.
Now moving on to an actual sample, I thought that in order to get a reliable reading of peak width (fwhm), peak broadening from instrumental broadening should be taken into consideration, and I assumed this is what the instr. parameter file created from the CeO2 reference would be used for.
In other words, I assumed that by copy/pasting the instrument parameters (UVWXYZ) obtained from the CeO2 reference sample onto the data from a different sample would effectively "adjust" for problems such as instr. peak broadening.
I was hoping you could point out any flaws in my logic and/or explain why later on in the video you refine the instr. parameters for your sample even though you already imported instr. parameters from a known reference. i.e: Once the Instr. parameters from the reference are found, why do they need to be further refined? Wouldn't doing so give a misleading peak width/shape reading? Did I misunderstand something in the steps you showed?
Forgive me for the painfully long comment--your time and help are greatly appreciated.
Best,
Alex
Good question and one that I had before as well. Technically, you are correct. The refinement from the instrument parameter should give you the peak shape that comes from the instrument meaning that any additional change the shape comes from the sample itself. Therefore, you should hold U,V,W constant and only adjust LX and LY. However, in practice, almost nobody does this.
This tutorial was really helpful. Thank you for sharing! Subscribed!!
To exclude a region, in background tree and hold “e” key on pattern. It will allow two bars to set the excluded region limits.
Very helpful!
Sir, How to make an output file for the electron density mapping from GSAS II refinement? For example in GSAS I, it can create the .grd and .fob files for the mapping.
how to get prm-format file? could cif file be converted to prm file?
In "Import phase", refining multiple patterns, You said we had to make sure all experimental conditions are same. "All experimental conditions" are the conditions we measure to collect XRD histograms, aren't they?
Yes
Another question is "peaks in background" showcased the phase you didn't import into your refinement, i.e. the impurities, isn't it?
does the act put " impurities' peaks into background' make the weight fraction of your both phases wrong?
@@ThangPVan_ technically yes. But common and if amount of impurities is small then impact is small. Gold standard approach is to add a known wt fraction of a standard like Si or Al2O3 and then you can calculate true amounts even if amorphous phase is present
yeah, the ROR method can calculate the true amounts of amorphous phases. But it's quite inconvenient when we had too many samples to refine @@TaylorSparks
Thanks for such good presentation.
my pleasure!
How do you create an instrument parameter file using GSAS-II? I did an IRF file in Fullprof. Is there a way I can use that in GSAS?
subversion.xray.aps.anl.gov/pyGSAS/Tutorials/CWInstDemo/FindProfParamCW.htm
I can send you a file with the different regions of the file explained if needed. email me
Really nice video. I have a question for exporting the calculation fitting data, how to export and load to such as OriginPro to reveal the original and fitting data. Many thanks for your time.
Sorry, I'm unfamiliar with that
After spending so much time on refinement of my pattern, I got dialogue box saying"Error Refinement failed" how to resolve this.. do I have to repeat it? Pls help Mr.Taylor
Unfortunately this is somewhat common. It's important to save often so you can revert to prior stages when error isn't present.
Currently, I am working on XRD refinement Unfortunately, I struggled a lot during the refinement process. Because I am adding new elements with the existing crystal system and convert to another phase or mixed phase. In this case, please explain "How to change the crystal phase and do refinement?" or how to optimize or find a new crystal phase after doping?.
I hope, you understand my question.
Please help to solve our problem.
thanks in advance
Hi your tutorial was very informative but I’m struggling to understand how much of the UVWXY parameters I should refine. Refining them individually one time each gives some good values above 0 and usually under 1, but if I keep refining them the values approach 0 or diverge to large positive values, suggesting a local minimum rather than global minimum was reached. How is this explained? Also how is X and Y different from the crystallite size and micro strain parameters under the phase/data tab, since they seem to correlate a lot? This step is crucial as it influences the extent of subsequent refinement, so I’d appreciate any suggestions.
typically think of UVWXY as just tools to get the right shape. So there aren't "right" values, per se. I typically do the one at a time then I start getting multiple at a time. XY differ from UVW because they give Lorentzian shape as opposed to a gaussian. Some refinements use these synonymously with crystal size/strain. However, that would be wrong because size and strain are phase-dependent whereas XY are global. You want to refine strain/size on a per-phase basis, not globally.
Thanks! Also do you happen to know how to refine anisotropic crystallite size parameters and whether I can check them against SEM images? Do I refine each parameter independently then together?
@@oliverwang4670 unfortunately I don't know how to do that. I've had some limited experiencing modeling overall powder patterns that are textured where you need to use anisotropic texturing factors but I don't think I'm an expert there.
No worries. Thanks so much for your help!
while downloading the cif files from materials project, I found that the primitive cell is a Triclinic P1 structure (for all crystals). How to convert this triclinic P1-primitive cell to the original symmetrized unit cell? and/or how to find the original crystal system from this primitive cell (triclinic P1) Is there any calculation or software is available?
In my case, the XRD pattern was changed to another unknown phase after doping. How to solve my problem. Please explain this. Thanks in advance
I don't think gsas is the right tool for this.
@@TaylorSparks Dear Sir, Thank you very much for the reply, Actually I have another problem. Currently, I am working on XRD refinement Unfortunately, I struggled a lot during the refinement process. Because I am adding new elements with the existing crystal system and convert to another phase or mixed phase. In this case, please explain "How to change the crystal phase and do refinement?" or how to optimize or find a new crystal phase after doping?.
I hope, you understand my question.
Please help to solve our problem.
thanks in advance
Hello. I did refinement using GSAS II. However, when I tried to change the color of my plot, it did not change anything. I took my file to run it on my colleague`s computer. This does not happen. Please advise which is the reason causing my color change problem?
John Luu color change? Is that something I talk about in this tutorial? Can you explain a bit more?
I mean when I want to export the plot of refinement and change its color of observed peak, cal peak, etc... but I cannot change the color
John Luu I see. I actually export the CSV and replot it myself in qtgrace. I can send you a tutorial link if you'd like. They look way better.
Thank you. Please send me the tuitorial via email: johnluu2809@gmail.com
Here you go ua-cam.com/video/YcvdmG6UKTw/v-deo.html
Thanks Taylor for a great tutorial. Could you please tell us where to find bond lengths for the refined structure?
Perhaps the easiest way is to export the CIF file, open it in VESTA and use their bond tool to show the bond. Are you familiar with CIF files and Vesta? It's quite easy to do but I can show you in another video of needed.
Sorry! I should have mentioned that I am using GSAS EXPGUI. GSASII seems much better. I tried to install it but I couldn't find the software for 32-bit Windows. Is there still a way to export CIF file and do the rest with VESTA?
Yes, you can still get a CIF from GSAS EXPGUI. Here is a tutorial. BTW- if you can, I strongly suggest switching to pyGSAS
www.ncnr.nist.gov/programs/crystallography/software/expgui/gsas2cif.html
Thank you so much.
Thank you so much for this great video. I have a question about the instrument parameter file I can't understand this subject (my XRD sample is (NaYF4:Yb, Er)). I used Highscore Expert software to check out the best fit of my sample. May I consider the best match as a reference file and put it as an instrument parameter? moreover, the only way I can extract the file from the expert is PDF or TXT file how can I apply it in GSAS format. I do appreciate it if you help me with this issue.
Hello Sir , I am new to GSAS 2 and would like to have a few things clarified regarding the same. What parameters you need to refine to improve the intensity of a XRD peaks. For my sample for few peaks the intensity is not matching. Also for solid solutions between two phase, whether we need to refine for both phase or for the host phase excluding the substituted phase.
Thank you
Hope I was able to clarify my doubt s.
we talk about that in this video. It depends on many things. Some of the common ones are atomic fractional occupancy, atom per site, and thermal displacement parameters.
@@TaylorSparks Thank you
Sir, If we have a solid solution between Compounds A and B, with A having 10 moles of B substituted within. Do we need to refine with both phases. My doubt is since the XRD gives the Crystal structure corresponding to A having a shift in 2 theta due to substitution by compound B. Does the lattice parameter is only needed to be refined? Since I have not peaks corresponding to B.
@@afineethcrazyworld346 okay, if you only see peaks corresponding to the a-phase then I would start by refining the lattice parameter. However, you should also consider looking at mixed occupancy on your sites. This will influence the intensity of your peaks. You can put both atoms on the site and refine their occupancy with the constraint that it adds up to one for example.
@@TaylorSparks sorry to ask but I don't have any idea about how to refine the occupancy. Would you please elaborate on the same
Thank you!
Hi, Thanks for the tutorial! May i know how to acquire the values for Rp, Rexp and Rf from the GSAS II? I am completely new to this software. Thanks.
Hi ,Taylor, thank you for such an informative video!, But, I have some problems with opening powder data. When I open my own .raw file, the software showed me "its a binary format file" and unable to read it. When I try to use your file, it showed me "unable to read" too. So I wonder if you have similar problems and how to solve it. Thanks a lot.
Try converting it to another format using powdll
Convert it to xy file that works well.
Hello, Taylor. Excellent and very helpful explanation. I would like to ask if you know any methodology to determine Amorphous Content (or Degree of Crystallinity) of a sample using GSAS-II or MAUD. I can't find it.
Yes, it's possible. You need to mix some crystalline material into your sample with a very specific known weight percent. For example, if you add 10% by weight of silicon and then you do the refinement you can use this to back out calculate what the amorphous fraction should be since the amount of silicon will be less than 10%.
@@TaylorSparks OK, I already have a data of a sample with a known amorphous percentage, I wanted to know how I make GSAS-II refine it correctly. Is it just uncheck Histogram Scale and check Phase Fraction?
Thanks for your great video. I have my xrd data and I have information related to my phases. but I dont know how I have to create my instrument parameter.
would you please help me how I can prepare instrument parameter for my data?
What I have to do exactly?
sakine khajavi sure! What instrument did you measure it on, what wavelength of radiation and what geometry etc?
Thanks alot for your help. The measurement was determined by X-ray diffraction
(XRD; Bruker D8 Focus; Cu Ka radiation). I cant understant what geometry do you mean? do you mean the angles?
my email adress is: sakine.khajavi@uqtr.ca
I mean is it Bragg Brentano vs debye scherrer etc. Probably Bragg-Brentano?
yes. It is Bragg-Brentano.
ok, I just sent the file. Let me know if I can help!
Hi Taylor,
Thanks for the tutorial. Do I understand correctly, that I only get the weight fraction at a Rw value below 5%?
In general, you should probably only report the weight fractions once you have gotten the weighted residual below 10% if you're going to be publishing your findings.
Hi!! Could you please do a video on how to update GSAS 2. No matter how many times I click on "check for update" it never seems to update, or maybe it does but I don't realize it. Thank you!! Your videos are super helpful.
That's a great suggestion. I actually don't have to do that right now. I will find out and make a video when I do.
I just tested and mine worked fine. Have you tried to uninstall and reinstall?
@@TaylorSparks No because to be honest it was kind of a pain to install it in the first place. But if I have to do so later on I might try it. Thank you for checking it and letting me know that my program has the issue!!
Hi!! I just reinstalled it and it’s up to date now. I just hope that this fixed it. If not, then i’ll just have to reinstall it again and again 😭(hopefully not though😂😅)
@@TaylorSparks Hi, sorry to bug you again but even though I had reinstalled it yesterday it still will not update from 4055 version to 4056. I looked at the terminal window of the program and I noticed it had a warning "Warning: failed to import the optimized Py3 pickle (_pickle)." Could that be the issue for why it will not update??
Can you tell me how to get the instrument file ?
Is it available in the GSAS webpage ?
The XRD machine I use is Panalytical.
Raghunandan S every instrument that you use should have its own instrument parameter file. If you have a panalytical instrument then I can send you a generic one, but you will need to modify it with your own instrument parameters such as the zero goniometer arm Etc.
hello Taylor, I can't open the .raw in GSAS-II?
what instrument did you measure your data on originally? There are a few different types of .Raw files. It's possible that it saved it as the wrong type. There are lots of diffraction converters though. It should be possible to convert it to the correct type.
@@TaylorSparksXRD panalytical x'pert pro
Panalytical should have no problem saving your file as a .Raw file. If you are having some trouble it's also possible to convert it using a conversion software such as PowDLL
@@TaylorSparks the files are already .raw bit still I have a problem in opening the files
@@sarahya3558 they might be Bruker raw files which are not the same as GSAS raw files.
Hi! Thank you for the video. I have a question though about refining the shape of the peaks. I would like to know the size of the particles of the sample. Does that still give you accurate results from the refinement if you refine the instrument parameters? As those are known and accurate, should not the thermal displacement, relative phase fractions or fractional occupancy be refined for? Thank you
Hi! if you want to determine particle size then you can use the well-known Scherrer formula. To use this formula you need to use the FWHM (full-width at half-max). However, broadening doesn't only come from your samples. You can also get instrumental broadening. Therefore, to correctly use Scherrer formula you should first scan a standard material which will have very sharp peaks. When you do so you'll be able to plot instrumental FWHM as a function of two-theta. Fit a line through this data and use the line to subtract instrumental broadening from your observed XRD scan FWHM so that you can more accurately estimate particle size.
To your second question, shouldn't thermal displacement, phase fraction etc be refined. Yes. However, I don't believe those should change your FWHM (assuming peaks don't overlap) since you are reading this directly from observed data, not the fit to the data.
Taylor Sparks Thank you very much!
Hey, Thank you for this informative tutorial video. Could you please send me the step by step file? I wish to perform Rietveld refinement on my XRD data having multiple phases. Thanks....
Sure, to what email?
Nice video. Do you know how can I create the .prm file? Or better, do you have a text document or do you know about a tutorial to do it by myself? Thanks in advance!
Carlos, I don't know of a formal text document that details the procedure. However, it is pretty straight-forward. You just open up the prm file in a notepad style editor and change the important bits to match your machine like the X-ray wavelength. You also modify the values for the zero, U, V, and W values for your instrument after you obtain them by scanning and fitting a standard with known lattice parameter. When you download the tutorial files for GSAS you will see several examples of prm files on different instruments.
I was opening and old .prm file and then I found the stuff you told me. Thanks for the answer!
Thanks for your great video. I have my xrd data and I have information related to my phases. but I dont know how I have to create my instrument parameter.
would you please help me how I can prepare instrument parameter for my data?
What I have to do exactly?
My email address is: sakine.khajavi@uqtr.ca
Can you send me this file ?
My email is samreensaeed489@gmail.com
@@tanveerg131 done!
Hey, you could not set limit in your video because your zoom button on plot window was turned on as shown in the screenshot below, by the way nice video...
oi66.tinypic.com/epehw0.jpg
Shoaib Muhammad thanks! I appreciate the help!
Excuse me, Sir. May I get your email?
Thank you
sure, post your email here and I'll reply
vinaagustinagultom10@gmail.com
Thank you, Sir
done
Thank you Sir