Brillouin scattering study on polycrystalline relaxor ferroelectrics

Abstract

Brillouin spectra of Pb(Yb1/2Nb1/2)O-3(PYN)-based relaxor ferroelectric ceramics were measured using a conventional tandem Fabry-Perot interferometer. The measured spectra were composed of a strong elastic peak and a broad doublet with a sharp cutoff at the high-frequency side. The broad doublet was attributed to the distributed Brillouin shift of the longitudinal acoustic mode owing to the scattering events at all scattering angles from 0degrees to 180degrees which is due to multiple reflections and refractions. From the sharp high-frequency cutoff of this band, which corresponds to the largest Brillouin shift of the backward scattering geometry, the average longitudinal sound velocities were estimated to be 4.22-4.33 km/s for PYN-based relaxor ceramics. The present results imply that Brillouin spectroscopy can be used to derive elastic properties of not only single crystals but also ceramic samples in the gigahertz range, which will be very important for high-frequency applications.