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Crystallite size wrong values
What is the reason for my Crystallite size always reach the maximum value in the TOPAS macro?
William #1
Member since May 2019 · 7 posts · Location: Bremen
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Subject: Crystallite size wrong values
Hello,

I am analyzing an in situ process (synchrotron radiation data) from a deformed steel alloy in TOPAS V4.2 (Launch mode). The material only contains two phases (austenite and ferrite).

My results from Rietveld refinements always return the maximum value of crystallite size (1999 nm) for the parameters (CS_L and CS_G) for all process steps and for both phases (austenite + ferrite). Another results like phase contents, microstrains and lattice parameter make sense. The calibration process with LaB6 and the wavelength are correct.

I have reviewed the TOPAS macro with another people but we were not able to figure out what was the problem.
If possible, I would like to send the TOPAS macro and the data (.xy) by e-mail for a better evaluation.

Best regards


William
AlanCoelho #2
Member since Aug 2011 · 320 posts
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The larger the values the smaller the effects. In other words large crystals result in small peak broadening and large errors in the crystallite size.
rowlesmr #3
Member since Oct 2011 · 231 posts
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In reply to post #1
It just shows that the broadening of the peaks is dominated by microstrain, not crystallite size. In this case, the crystallite size becomes very large, indicating that there is very little broadening.
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Matthew
William #4
Member since May 2019 · 7 posts · Location: Bremen
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Thanks Alan and rowlesmr!



Regards

William
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