1. Physics Department, University of Arkansas, Fayetteville, Arkansas 72701, USA

Correspondence to: L. Bellaiche Correspondence and requests for materials should be addressed to L.B. (e-mail: Email: laurent@comp.uark.edu).

Abstract

Complex insulating perovskite alloys are of considerable technological interest because of their large dielectric and piezoelectric responses. Examples of such alloys include (Ba_1-xSr_x)TiO₃, which has emerged as a leading candidate dielectric material for the memory-cell capacitors in dynamic random access memories¹; and Pb(Zr_1-xTi_x)O₃ (PZT), which is widely used in transducers and actuators². The rich variety of structural phases that these alloys can exhibit, and the challenge of relating their anomalous properties to the microscopic structure, make them attractive from a fundamental point of view. Theoretical investigations of modifications to the atomic ordering of these alloys suggest the existence of further unexpected structural properties³ and hold promise for the development of new functional materials with improved electromechanical properties. Here we report ab initio calculations that show that a certain class of atomic rearrangement should lead simultaneously to large electromechanical responses and to unusual structural phases in a given class of perovskite alloys. Our simulations also reveal the microscopic mechanism responsible for these anomalies.