Phase Diagram of the Perovskite System (1−x)BiScO3-xPbTiO3

Abstract

The perovskite (1−x)BiScO3-xPbTiO3 (BS-PT) system exhibits a large piezoelectric coefficient (d33>460pC∕N in polycrystalline form) and a high Curie temperature TC=450°C in the vicinity of the morphotropic phase boundary (x=0.64mol fraction PbTiO3), which separates the rhombohedral and tetragonal phases. The present contribution reports on revisions to the BiScO3-PbTiO3 phase diagram specifically, (i) the compositional dependence of the octahedral tilt-transition temperature (x<0.62mol fraction PT), as determined using variable-temperature transmission electron microscopy, (ii) high-temperature curvature of the rhombohedral-tetragonal morphotropic phase boundary determined using dielectric measurements on single crystals, and (iii) Curie temperatures in the tetragonal phase field, which exceed that of the PbTiO3 end member.