Does anyone tell me about the constant values of Scherer (K) in eq. G.S=k λ / β cos(θ). Some researchers depend on the value 0.9 ; some 0, 91 ; and some 0.94 ?. Is this difference in opinions came because of a difference in the form of geometric grained or what?.
(Note that the value of K in some literatures =2(ln2/π)1/2 =0.939437).
Hi dear Foaad shakir
The constant of proportionality, K (the Scherrer constant) depends on the how the width is determined, the shape of the crystal, and the size distribution.
http://prism.mit.edu/xray/newsite/oldsite/5a%20Estimating%20Crystallite%20Size%20Using%20XRD.pdf
To calculate the crystallite size, You can also try a so called Williamson-Hall analysis to get a more accurate and scientific result.
Best Regards
Williamson-Hall analysis mentioned by @Pourya Norouzzadeh : was introduced in 1953 in
G. K. Williamson, W. H. Hall, X-ray line broadening from filed aluminium and wolfram, Acta Metallurgica 1 (1) (1953) 22 – 31.
For a detailed example of the application of Williamson-Hall analysis, see
Synthesis and structural ordering of nano-sized Ba3B 0 Nb2O9 (B0 = Ca and Zn) powders
https://arxiv.org/pdf/1308.1644.pdf
Dear Foaad Shakir ,
In addition to the helpful answers, I think the following article includes useful details about the Scherrer constant.
JI Langford and AJC Wilson, “Scherrer after sixty years: A survey and some new results in the determination of crystallite size,” J. Appl. Cryst. 11 (1978) p102-113.
Best regards
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