Calculated intensity is lower than experimental for several peaks including 110, which indicates beside preferred orientation other factors may be possible like peak profile anisotropy.

First try structure-less approach i.e. Le-Bail fitting in which peak intensity is free parameter. If you got adequate Le-Bail fitting then preferred orientation and atomic parameters (like thermal, composition inhomogeneity) will be source of this mismatch.

If Le-Bail fitting is poor then peak profile related issues (cause by microstructure of material like crystallite shape, size, microstrain etc) are also playing role in it. First got best fit with Le-Bail method so that profile related effects are properly accounted and fix these parameters. Then go for Rietveld refinement and refine atomic parameters initially followed by preferred orientation (if required).

Ashok Bhakar

Dear Sir,

When you are doing atomic parameters refinement, will you suggest to do oxygen atom as well to refine or you keep the oxygen position fix, since we can only refine Ti as oxygen is lighter atom?

Secondly, in microstructure fitting there are lots of models, which model we can choose on what factors are by seeing the pattern is that any specific literature avilable.

Another question on what basis we need to choose to refiene thermal parameters, anisotropic or isotropic, is it only good to be fitted?

Sanjeev Gupta

First try LeBail fitting, it will help a lot in answering your query. Is it giving good fit to XRD data or not?

You asked "Secondly, in microstructure fitting there are lots of models, which model we can choose on what factors are by seeing the pattern is that any specific literature available". If your peak profile is isotropic in nature then you may skip this (if not interested in microstructure i.e. size-strain contribution).

Only when peak shapes are anisotropic, then particular model is required. For anisotropic peak broadening due to microstrain there are only a few models depending upon crystal systems: Please see table 1 of Stephen's paper (majority Rietveld software used this model):

Article Phenomenological Model of Anisotropic Peak Broadening in Pow...

If anisotropy is due to size effect, choose model accordingly. First confirm it that anisotropic peak profiles are present or not in your sample, then decide.

Choose Ti & O positions from literature and keep thermal parameter isotropic (in majority cases isotropic thermal parameters are sufficient).