Diffuse scattering and Monte Carlo studies of relaxor ferroelectrics

Abstract

A renewed interest in the field of ferroelectricity has taken place in recent years since the finding of exceptional piezoelectric properties in the lead-oxide class of relaxor ferroelectric materials typified by the disordered perovskite PbZn1/3Nb2/3O3 (PZN). Although PZN and numerous related materials have been extensively studied over a long period, a detailed understanding of the exact nature of their polar nanostructure has still not emerged. In this article, we describe the development of Monte Carlo computer models, which seek to account for the detailed three-dimensional (3-D) diffuse neutron scattering data that have been recorded from a single crystal of PZN. It has been established that the observed diffuse patterns are due to planar nanodomains oriented normal to the six 〈110〉 directions, but there is still some uncertainty concerning the direction of the local Pb ionic shifts, which remains an area of controversy. It is argued that further detailed analysis and experiments in which data are recorded with the crystal in an applied field should allow these remaining issues to be resolved.