XRD Scherrer Equation -- need explanation

[physicist888]

Hi everybody
Actually i need to calculate a cristallite nanoparticles size by using my XRD measurement results. I looked in some sites and published papers, folks are used an equation called Scherrer equation to calculate the radius of a nanoparticle. I've found in an another forum this informations [ Crystallite Size = (K * L) / (FWHM x Cos(theta)) K is the shape factor of the average crystallite (expected shape factor is 0.9). L is the wavelength (usually 1.54056 Å for Cu K(alpha)sub1, and theta is the peak position.] . I hope that someone can verify those informations for me and explain what does the Lettre K represent ( what value should i use for K) .

Thanks for your attention

 

[fresh_42]

$K$ is the shape factor. Usually between 0.9 and 1. See
https://en.wikipedia.org/wiki/Scherrer_equation

Here is the original paper (page 98f., German, 1918)
https://gdz.sub.uni-goettingen.de/id/PPN252457811_1918