Perovskite solid solutions with multiferroic morphotropic phase boundaries and property enhancement

Abstract

Recently, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of phases in the BiFeO 3 -BiCoO 3 perovskite binary system, associated with the existence of a discontinuous morphotropic phase boundary (MPB) between multiferroic polymorphs of rhombohedral and tetragonal symmetries. This might be a general property of multiferroic phase instabilities, and a novel promising approach for room temperature magnetoelectricity. We review here our current investigations on the identification and study of additional material systems, alternative to BiFeO 3 -BiCoO 3 that has only been obtained by high pressure synthesis. Three systems, whose phase diagrams were, in principle, liable to show multiferroic MPBs have been addressed: the BiMnO 3 -PbTiO 3 and BiFeO 3 -PbTiO 3 binary systems, and the BiFeO 3 -BiMnO 3 -PbTiO 3 ternary one. A comprehensive study of multiferroism across different solid solutions was carried out based on electrical and magnetic characterizations, complemented with mechanical and electromechanical measurements. An in-depth structural analysis was also accomplished when necessary.