# X-Ray Diffraction peak width due to micro-strain

I understand that the peak-width of diffraction data increases with increasing amounts of heterogeneous, localized (AKA "micro-") strain.

So, if you have a single crystal with atomic impurities in it that each create micro-strain in the lattice, you would expect the amount of peak-broadening to scale with the amount of the impurity—Right?

But, if there is enough impurity in the crystal, eventually the impurities would be spaced close enough together that it seems the micro-strain fields associated with each impurity would start to "blend" together into something more homogeneous, and then peaks would actually decrease in width (and probably shift)—Right?

Am I correct here? While there is plenty in the literature that describes the effect of micro-strain on diffracted peak width, I can't seem to find anything in the literature that describes when inherently heterogeneous micro-strains in a lattice might become closely enough spaced to diffract as a homogenous strain. Basically, I'm looking for journal or textbook references to guide me.

Thanks!

Hey,

I'm not 100% sure but sounds as if looking into diffraction peak-broadening and peak-shift effects might be your thing. Not sure if its entirely applicable but:

http://www.jmst.org/fileup/PDF/02459.pdf

and of course.. Warren's book on x-ray diffraction (https://www.amazon.com/dp/0486663175/?tag=pfamazon01-20) might be useful for you?

I can't quote the exact thing but the stacking fault probability equation consists of a and b contributions (i.e. deformation faults and growth faults from peak broadening and peak shifts). If the only contribution to your single crystal comes from the impurities then you may be able to co-relate how much impurities are in the system... assuming you can get values of an unstrained lattice... c.f. the first link.

Hope I'm not misunderstanding/being confusing and that helps.

Regards,
Let

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