Check this

http://link.springer.com/article/10.1134/1.1130964

Hi !

Going nano affects Raman bands lineshapes and you can, in principle, fit the spectra using size as a parameter. Yet, this won't be as straigthforward as using Sherrer equation for XRD. The shift will depend on the shape of your nanocrystals, on their size distribution (you will probe at least 1 square micrometer), on their crystallinity, ...

Unless someone has already published results on very similar materials, this will be a Research activity in itself.

I co-authored a review paper on that matter in 2007 :

Gouadec, G. and Colomban Ph., "Raman Spectroscopy of Nanomaterials: How Spectra Relate to Disorder, Particle Size and Mechanical Properties," Prog. Cryst. Growth Charact. Mater., vol. 53, pp. 1-56, 2007.

I hope this will help.