Phase transformation via a monoclinic phase in relaxor-based ferroelectric crystal (PbMg1/3Nb2/3O3)1-x(PbTiO3)x

Abstract

A monoclinic phase is evidenced between rhombohedral and cubic phases in a 〈111〉-cut single crystal (PbMg1/3Nb2/3O3)0.67(PbTiO3)0.33 (PMN-33% PT) from observation of domain structures. Near 360 K the structure begins to distort from the rhombohedral toward the tetragonal phase through monoclinic domains (probably MA type but perhaps MB type). However, the present 〈111〉-cut crystal seems to disfavor the tetragonal phase and persists in the monoclinic phase up to T∼420K, where the cubic phase begins to develop. Temperature-dependent orientations of optical indicatrices of domains indicate polarization rotations within the monoclinic planes. In addition, a previously electric-field-cooled process enhances a long-range transformation.