I have calculated strain in my sample (Ba-doped LaGaO3) using W-H plots. For the linear fit of data, the R2 value obtained is 0.74. I want to know the specific reason for the scattered data points.
the specific reason is called physics.. the one your are largely forgetting here.
First, what you obtain from a WH plot is not a strain but is the so-called microstrain and that's a quantity related to the variance of the lattice strain distribution. Second, the WH plot should be used QUALITATIVELY and not quantitatively, as it is based on arbitrary hypotheses: you sum the breadths (valid for Lorentz peaks.. note that the size part is Scherrer equation, valid in the Gaussian limit), you don't consider the correct profile for size, you don't consider any size distribution or domain shape, you ignore the elastic anisotropy for the microstrain or its actual source. In several cases people also ignore the instrumental broadening and the actual shape information.
So the reason can be any of those. Without a proper modelling of the profiles, it is impossible to say which of these match your case.
You are working with a perovskite, so shape anisotropy and stacking defects are likely, but it is impossible to judge without a pattern and some proper modelling of the peak shapes
Sometimes the scattering may be non-arbitrary: Certain HKLs deviate stronger due to anisotropy. The best way is to analyse W-H for HKL and nHnKnL (if any) separately.
Kapil Sood The Williamson-Hall Plot. W-H plot is used to calculate the crystallite size and microstrain from complex XRD data. That's when both the crystallite size and microstrain vary as a function of the Bragg's angle, we can only calculate these parameters from XRD data using W-H plot. I have provided the practice file (Origin file) as well as the calculation file (Excel file) in the video description. Thanks
https://youtu.be/ipX3iUJ5VcU
- Badges
- Science topic