Raman scattering yields cubic crystal grain orientation


The paper proposes a fully optical method for determination of a cubic crystal grain orientation in a sample inspected by a Raman microscope. The method is based on a universal and strong polarisation anisotropy of the Raman scattering by doubly degenerate optic phonon modes. The feasibility of the approach is demonstrated by comparing grain orientations in a polycrystalline cubic lacunar spinel GaV4S8 determined independently using electron backscatter diffraction and Raman scattering methods.

Contact person: Jiří Hlinka

Grain morphology of the investigated GaV4S8 ceramics
Grain morphology of the investigated GaV4S8 ceramics.
(a) Scanning electron microscope image of an area of interest with sample coordinate system as an inset;
(b) Inverse pole figure map from EBSD analysis of the area in (a);
(c) positions of four grains chosen for detailed Raman measurements, indicated projections of elementary cubic cells clarify their crystallographic orientation;
(d) unit triangle with the colour code of the inverse pole figure map;
(e) surface normals of the chosen grains;
(f) Parallel-polarised Raman scattering intensity ratios detected from the four grains, which allows determination of their crystallographic orientation independent of the EBSD analysis. Data shows intensity ratio at selected frequencies as a function of the angle ϕ between the polariser and the reference direction on the sample surface.