SIZE ANALYSIS
This page explains the commands for the analysis of the average size of crystalline domains. It can be performed only on X-ray powder diffraction patterns and it is based on the study of the peak width in the profile, from which the average size of the crystallites composing the powder sample can be assessed through the Scherrer equation. The study is based on a specific peak if commands theta0, toltheta0, theta0st, toltheta0st are are provided. In this case the average size is related to the orientation given by the specific peak considered. In addition, the estimated size of crystalline domains has contribution from both their true size and microstrain. If above commands are not provided, all main peaks of the profiles are considered for the analysis, and a study based on Williamson-Hall plots is performed, allowing to separate contribution from size and microstrain. Note that profiles should be preprocessed by removing the background before starting the size analysis. The commands are:
nstandard
Defines if the profile of a standard compound is used to determine the experimental broadening of peak shape. The command should follow the file command of the profile of the standard.
Defines the value of the independent variable (usually 2Theta) which locates the center of the peak of the profile to be considered for size analysis.
Defines half the range the independent variable which locates the width of the peak of the profile to be considered for size analysis.
Defines the value of the independent variable which locates the center of the peak of the profile of the standard compound to be considered for calculating the peak shape experimental broadening.
Defines half the range the independent variable which locates the width of the peak of the profile of the standard compound to be considered for for calculating the peak shape experimental broadening. If not provided, toltheta0st is assumed to be equal to toltheta0.
Defines the wavelength of the X-ray beam, in Angstroms.
Defines the function to be used for fitting the profile peaks.
0 Gaussian
1 Lorentzian
2 Pseudo-Voigt (default)
