Coexistence of tetragonal and rhombohedral phases at the morphotropic phase boundary in pzt powders I. X-ray diffraction studies

Abstract

The morphotropic phase boundary (MPB) in PbZr_xTi_1-xO₃ (PZT) powders prepared by a novel semi-wet route is shown to be around x = 0.525. XRD evidence is presented for the first time to demonstrate the coexistence of the tetragonal (T) and rhombohedral (R) phases in such powders over a very narrow composition range of Δx ~ 0.01 around the MPB composition. High temperature XRD studies show that the mixture of T and R phases first transforms into T phase and then to cubic phase on annealing at successively higher temperatures suggesting that the two phase region is slightly tilted towards the Zr rich end. Tentative arguments are advanced in favor of the first order nature of the MPB.