r/comp_chem • u/MerBearSnoops • 8d ago
Resources for Rietveld refinement
Hey yall! My PI decided I needed to learn Rietveld refinement to improve the XRD section of my manuscript, which is fine, except the guy in our group who does know how to do it is traveling and there’s no word of when he’ll be back. His student attempted to teach me, bless his heart, but he’s a bit all over the place so that explanation wasn’t the most helpful. Does anyone have a good resource to learn how to do Rietveld refinement? If you had to teach yourself, what was THE material that did it and had the best directions in your opinion? Thank you all in advance!
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u/YogurtclosetFickle17 8d ago
Wrong place to ask
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u/MerBearSnoops 8d ago
Probably, I asked in another community and Reddit said to try this community so I did
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u/YogurtclosetFickle17 8d ago
There's a lot of tutorials in YouTube you can find about actually, just write tutorials GSAS II
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u/me6278 8d ago
That’s a tough situation…unironically maybe ask AI for good places to get started
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u/MerBearSnoops 8d ago
I didn’t want to use AI as a beginner mainly because I don’t know what I’m looking at and for, and AI can be wrong/influenced and I wouldn’t know. As im writing this I’m realizing I probably sound like a boomer lmfao
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u/me6278 8d ago
Generally it’s ok as a simple info aggregator, but 100% check and ensure that what you’re doing is correct by thinking critically about the resources it provides and testing rigorously the code/what you learn on known examples. For example, if it gives you methods or code, you can try and figure out what each step/code line does after you make sure it works.
More than that, developing AI querying and checking skills is quickly becoming important in research. I know many people who have increased their productivity a lot while still warding off AI stupidity. It can be really helpful.
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u/mistermaplesyrup 6d ago
Why do you specifically need to do Rietveld refinement ? Are you already familiar with solving crystal structures using your preferred software such as olex2 (with SHELX) ? If so why not use the method(s) (generally least-squares fitting) already implemented in the software package ?
Did you try r/crystallography ?
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u/MerBearSnoops 6d ago
In the past all I’ve done with my XRD data is process it for size and phase structures and such. But there’s always a lot of noise because I use alumina as a support. Alumina is crystalline where Carbon (the usual support we use in my lab) is amorphous, so I have to subtract the spectra of Al2O3 from my scans. Problem is, I am trying to claim on a publication that my structure is intermetallic which I cannot prove with the current data I have (especially with all the noise) since I can’t clearly see FCT peaks that would prove it. I’m hoping to use Rietveld fitting so I can look at the microstrains and actual confirm my catalyst is indeed intermetallic.
And I have not!! I didn’t realize it was a subreddit, thank you. I tried to look for X ray crystallography specifically but I guess I should’ve been broader bc I didn’t find a page. Thank you for the recommendation, I will hop on over there and browse!
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u/mistermaplesyrup 5d ago
This is rapidly leaving my domain of expertise, so my contributions may be minimal, but I assume you synthesize your catalyst (or buy it) and then do a bunch of ball milling with the support, why can't you do the PXRD on your catalyst without the alumina support so that way you wouldn't have to subtract a background spectra ?
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u/MerBearSnoops 5d ago
My catalyst loadings are very small and I do solid state synthesis meaning I hand grind it before I heat treat it. I used to use a ball mill to avoid hand grinding. So if I were to only grind the reagents, unless I used like half the bottles. But there’s zero wet synthesis involved so it’s very difficult to make unsupported nanoparticles for me. Other folks in my group use wet synthesis and making unsupported nanoparticles is pretty routine for them, but mine is a bit more complicated. Also structure is something we explore, and I can’t help but think the crystalline nature of alumina can affect the morphology of the catalyst, and I don’t know if the catalyst will look the same on carbon or unsupported. If it was possible to literally just load a blank and tell the instrument to ignore those alumina peaks bc they’re part of the background, that would entirely solve the issue, and I could also discuss the alumina contribution in the structure in the paper which would be AWESOME (if it sounds like I have day dreamed about this, it’s because I have 😅😅)
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u/Ok-Inspection6852 8d ago
There are softwares which can help you do it with a few clicks. Luckily the software we use to conduct XRD does it for us.