Dielectric and piezoelectric properties in the BiScO3-PbTiO3-PbO•SnO2 ternary system

The effect of Sn substitution on the dielectric and piezoelectric properties of BiSCO3-PbTiO3 was investigated in the ternary system, (1 - x) {(1 - y)BiSCO3-yPbO.SnO2}-xPbTiO(3) (x = 0.43-0.63, y = 0.25-0.75). The ferroelectric phase transition temperature near morphotropic phase boundary (MPB) decreased with increasing Sn content from 450degreesC (x, y = 0.64, 0) down to similar to250degreesC for the composition with x, y = 0.46, 0.75. Piezoelectric activity (d(33) = 460-465 and k(p) = 0.54) in Sn-substituted MPBs remained at similar levels to the pure 0.46BiSCO(3)-0.64PbTiO(3) MPB, with Sn content of up to y = 0.5. However, further Sn-additions lead to decreased electromechanical performance and the formation of secondary phases such as SnO2. Broad temperature dependence of the permittivity near the ferroelectric phase transition was assessed by a diffuseness parameter delta, which generally decreased with firing temperature in the range of 1050-1250degreesC. The temperature of the permittivity maximum (T-max,) increased with measuring frequency, a characteristic consistent with relaxor ferroelectric materials.