Can Raman be used to analyse crystallinity of a material?

Yes.  In most cases Raman scattering is sensitive to the degree of crystallinity in a sample.  Typically a crystalline material yields a spectrum with very sharp, intense Raman peaks, whilst an amorphous material will show broader less intense Raman peaks.  These two states (e.g., fully amorphous, or fully crystalline) can be considered as spectral extremes, and a Raman spectrum from an intermediate state (e.g., partially crystalline) will have characteristics which are intermediate in terms of peak intensity and width (sharpness).  Differences between intermediate states can be subtle, and it is often useful to have high spectral resolution capability so that minor spectral changes can be confidently characterised.

Using software peak fitting routines it is possible to accurately calculate peak width and intensity, which can then be used, with calibration and comparison with other techniques, as a quantitative measure of crystallinity.  Similar analysis of Raman maps allows images of degree of crystallinity to be produced.

Raman spectra of zircon, showing typical amorphous (blue) and crystalline (red) spectra.
Raman spectra of zircon, showing typical amorphous (blue) and crystalline (red) spectra.
Back to FAQs