Hello,
I know that profex, Mercury and MAUD can all fit powder XRD data to structual data given by an CIF file for example.
However, I can't find a free software where I can fit only the peaks along a given direction, for instance only along [001]. Whenever I load my CIF file into the software it shows all possible XRD peaks you would get when you do powder diffraction, this I can obviously not fit with my thin film data.
Thank you and have a nice day,
Simon
Hello Simon Rombauer,
Each peak in a XRD pattern represents one crystal plane. So, every crystal has more than one peak because they have multiple crystal planes, like 100, 200, 111, etc.
If you see only one peak in your pattern, and it is reasonable because you made a thin film, it means that you have a very intense preferred orientation. Preferred orientation happens when your sample has many agglomeration, or crystallites in a needle-like form, etc.
The refinement softwares can model preferred orientation. What softwares do you use? I think I can help you with this.
Best regards,
Ricardo Tadeu
Dear Ricardo Tadeu Maia, thank you for your answer.
Yes, I was expressing myself not clearly.
I see 001, 002, and 003 peaks (+ each accompanied by one peak due to strain of the top layer on my substrate).
The substrate ist cubic SrTiO3 and I've grown LaVO3 ontop of it. I was using MAUD but can't find an option to enter the preferred orientation, using the free version of Mercury 4.2.0 I can see the option under Calculate -> Powder Structure -> Customise -> Preferred orientation, but unfortunately it is greyed-out so I assume this can't be done with the free version.
I have also installed profex but I can't find to enter a preferred direction there either. Of course I can always fit the XRD data manually using origin, but I thought there must be a more elegant way using one of the many XRD-analyze softwares together with a provided CIF file.
Best,
Simon
Dear Simon Rombauer
About this comment "I see 001, 002, and 003 peaks (+ each accompanied by one peak due to strain of the top layer on my substrate)", could it be an influence of Kalpha2 radiation?
I use GSAS-II and EXPO2014, they can model preferred orientation better than Profex. I can try to fit your sample with MAUD.
I am sure they are due to strain of my thin layer film grown by PLD, the XRD measurement software can filter out the alpha and beta lines during measurement. Thank you for your suggestions, I will check them out!
I've seen in MAUD that you can exclude certain regions from refinement, but it didn't work somehow, it still tried to fit the nonexisting peaks inbetween...
Please, have a try, I would love to know if it's a bug or if I have done something wrong. (Just for testing porpuses, I have changed the lattice parameters sligthly in the CIF files to fit even better the observed peaks)
Muito obrigado and have a nice day,
Simon
Well, is this a simulated data, or did you linearize it? It doesn't have a background.
Also, I consider the possibility of the structure have been deformed to a lower symmetry, because the peaks looks splitted, and this is not because of strain. I will try to fit it in GSAS-II and other softwares.
I measured it using the Rigaku SmartLab. Perhabs the software that controls the measurement does auto-removal of the background, I can't tell right now.
The double peak almost certainly comes from strain of the LVO layer, as I have seen the same phenomena with STO/EuTiO3 and even STO/STO films when growing them by PLD (strain dependens on laser fluence, I had 4 J/cm²), furthermore it is reported to occur in literature as well (e.g. Article Octahedral tilting in strained LaVO_ {3} thin films
, Fig.1).I have managed to fit the peaks in GSAS-II, but the auto-indexing fails, is there an option to set a preferred direction in GSAS-II? (Thanks again for the suggestion, GSAS is much more intuitive and easy to work with than previous tools).
Best,
Simon
In GSAS-II, in Phases, select the phase you want, go to the Data tab, at the bottom, there is the option to model a preferred orientation with March-Dollase for a crystal plane. It starts with 1, to increase preferred orientation, make it lower.
However, it looks like it could have more than one plane with preferred orientation, I don't know if this is possible and I've never dealt with this, but there are peaks of the phases that completely dissappear.
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