Polarization leakage and asymmetric Raman line broadening in microwave dielectric ZrTiO4

Abstract

Nano-scale structural characteristics and broken symmetry associated with the formation of incommensurately ordered phase from the high-temperature disordered phase of ZrTiO4 were studied using Raman scattering method. For this purpose, the Raman peak at 815 cm(-1) caused by the A(g)-symmetry normal mode was employed as a nano-structural probe. A polarization leakage was observed in the polarized Raman spectra of single-crystal ZrTiO4. The observed leakage was attributed to the random orientation of the short-range ordered domains in the beginning stage of the normal-to-incommensurate transformation. The computational result based on the phonon-confinement model indicated that the asymmetric Raman line broadening in the incommensurately ordered ZrTiO4 single-crystal was directly related to the existence of the faulted boundary having the average periodicity of 3.9 nm along the a-axis. (C) 2003 Elsevier Science Ltd. All rights reserved.