Domain Growth in Pb(Mg1/3Ta2/3)O3 Perovskite Relaxor Ferroelectric Oxides

Abstract

Extensive studies that have been conducted on the Pb(Mg1/3Nb2/3)O3 (PMN) family of relaxor ferroelectrics have led to the establishment and acceptance of the“space‐charge” model as a basis for explaining their structures and dielectric properties. In this model, the arrangement of the metal cations on the octahedral sites of the perovskite structure is interpreted in terms of the formation of nega‐tively charged ordered nanodomains that are dispersed in a positively charged disordered matrix. The primary experi‐mental support for this interpretation has come from the apparent absence of any growth of the domains or change in the degree of ordering as the heat treatment is extended. Here, we report on experiments that have been conducted on the tantalate relaxor, Pb(Mg1/3Ta2/3)O3(PMT), and its solid solutions with PbZrO3, in which the size of the do‐mains and the degree of cation ordering have been in‐creased by two orders of magnitude through annealing that has been conducted at a temperature of 1325°C. Moreover, fully ordered ceramics that are comprised of large domains retain relaxor behavior. These results cannot be explained by the space‐charge model and support a charge‐balanced, “random‐site” model for the ordering of the metal cations