Phase diagram of the perovskite system (1-x)BiScO3-xPbTiO3

The perovskite (1-x)BiScO3-xPbTiO(3) (BS-PT) system exhibits a large piezoelectric coefficient (d(33)>460pC/N in polycrystalline form) and a high Curie temperature T-C=450degreesC in the vicinity of the morphotropic phase boundary (x=0.64 mol 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<0.62 mol 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. (C) 2004 American Institute of Physics.