Please follow this link

https://www.researchgate.net/publication/322076509_Crystallite_Size_and_Strain_Analysis_of_Nanocrystalline_La07Sr03MnO3_Perovskite_by_Williamson-Hall_Plot_Method

By peak fitting or simply manually by 'hand' *).

For typs of peak fitting please have a look for example at the following link: https://www.researchgate.net/post/Average_crystallite_size_estimated_by_WH_plot_by_fitting_with_a_gaussian_lorentzian_and_pseudo_voigt_profile_gives_much_different_values?_iepl%5BgeneralViewId%5D=CV5D7m5cQ2l56toD0S7RslbBlJNJF04Omi1R&_iepl%5Bcontexts%5D%5B0%5D=searchReact&_iepl%5BviewId%5D=MC7B4K6iEJ6vqNM9fZ3Y0i9xGd0YCMfRsxS1&_iepl%5BsearchType%5D=question&_iepl%5Bdata%5D%5BcountMoreThan20%5D=1&_iepl%5Bdata%5D%5BinteractedWithPosition3%5D=1&_iepl%5Bposition%5D=3&_iepl%5BrgKey%5D=PT%3A583d996ef7b67ee9987cb2cf&_iepl%5BtargetEntityId%5D=Q%3A583d996ef7b67ee9987cb2cf&_iepl%5BinteractionType%5D=questionView

and

https://www.researchgate.net/post/How_can_I_find_the_FWHM_from_an_XRD_graph

But please do not forget:

a) to correct the FWHM values for the instrumental broadening

and

b) convert the resulting net FWHM values into radian units

*) please take the full widths of the peaks (in 2theta) at half of the net peak heights ( i.e. net peak heights above background)

Use Reitveld refinement.

Dear Tirupati,

The values of FWHM can be estimated by two methods: (1) by manually fitting the peaks using Gaussian function and (2) by performing Rietveld refinement of XRD data using some standard software. And subtract instrumental peak broadening from the previous FWHM values. Now the FWHM has only due to crystallite size and strain. Then use the W-H relation for the calculation of crystallite size and strain.

thanks due to all esteemed people for helping me on this topic thanks you all

See this video

How to Calculate FWHM in XRD

https://youtu.be/WauGqgz3vy8

Using ANDROID APP: https://www.youtube.com/watch?v=XrYkU7xAyvQ

Using ORIGIN: https://www.youtube.com/watch?v=XrYkU7xAyvQ