Processing and properties of hafnium‐doped tin‐modified lead zirconate titanate 95/5 ceramics

Abstract

AbstractNiobium (Nb)‐doped lead‐tin‐zirconate‐titanate (PSZT) ceramics near the lead‐zirconate‐titanate 95/5 orthorhombic AFE‐rhombohedral FE morphotropic phase boundary (PSZT 13.5/81/5.5 ‐1.6Nb) were prepared with up to 10 mol.% of hafnium (Hf) substituted for zirconium. The ceramics were prepared by a traditional solid‐state synthesis route and sintered to near full density at 1150°C for 6 h in sealed alumina crucibles with self‐same material as the lead vapor source. All compositions were ∼98% dense with no detectable secondary phases by X‐ray diffraction. The grain size was ∼3 μm for all compositions, consisting of equiaxed grains with intergranular porosity. The compositions exhibited remnant polarization values of ∼32 μC/cm2. Depolarization by the hydrostatic pressure‐induced FE‐AFE phase transition occurred at 310 MPa for all compositions, resulting in a total depolarization output of 32.4 μC/cm2 for the PSZT ceramics. Evaluation of the R3c‐R3m and R3m‐Pm m phase transition temperatures by impedance spectroscopy showed temperatures on heating ranging from 86 to 92°C and 186 to 182°C, respectively, for increasing nominal Hf content. Thermal hysteresis of the phase transitions was also observed in the ceramics, with the transition temperature on cooling being 1–4°C lower. The study demonstrated that the PSZT ceramics are relatively insensitive to variations in Hf content in the range of 0 to 10 mol.%.