Piezoelectric properties and phase transition temperatures of the solid solution of (1-x)(Bi0.5Na0.5)TiO3-xSrTiO3

The phase diagram of (1 - x)(Bi0.5Na0.5)TiO3-xSrTiO(3) was completed and investigations on polarization and strain in this system were carried out. (1 - x)(Bi0.5Na0.5)TiO3-xSrTiO(3)-ceramics were prepared by conventional mixed oxide processing. The depolarization temperature (T-d), the temperature of the rhombohedral-tetragonal phase transition (Tr-1) and the Curie temperature (T-m) were determined by measuring the temperature dependence of the relative permittivity. All solid solutions of (1 - x)(Bi0.5Na0.5)TiO3-xSrTiO(3) show relaxor behavior (A-site relaxor). From XRD-measurements a broad maximum of the lattice parameter can be observed around x = 0.5 but no structural evidence for a morphotropic phase boundary was found. SEM-analysis revealed a decrease of the grain size for increasing SrTiO3-content. At room temperature a maximum of strain of about 0.29% was found at x = 0.25 which coincides with a transition from a ferroelectric to an antiferroelectric phase. The temperature dependence of the displacement indicates an additional contribution from a structural transition (rhombohedral-tetragonal), which would be of certain relevance for the existence of a morphotropic phase boundary. (C) 2010 Elsevier Ltd. All rights reserved.