Using psdvoigt in origin 9.0, I obtain two different FWHM parameters (wG and wL). Which one of these should I use for determinating the crystallite size using Scherrer equation? thank you
Crystallite size lie on Lorentzian broadening, strain lie on Gaussian broadening.
Did u use the standard sample to get the instrument information?
For powder sample u must use all the peaks up to higher 2theta.
Even if powder and use WH-plot (size-strain analysis) u still can end up with 5-10% deviation if ur powder statistic is not good enough, or u had anisotropic shape or preferred orientation.