Dielectric, Piezoelectric, and Pyroelectric Properties of Lead Zirconate—Lead Zinc Niobate Ceramics

New piezoelectric and pyroelectric ceramics consisting of antiferroelectric lead zirconate (PZ) and relaxor ferroelectric lead zinc niobate (PZN) are studied from an application view-point of the field-induced antiferroelectric-to-ferroelectric phase transition. An antiferroelectric-ferroelectric phase boundary exists in PbZr_x(Zn_1/3Nb_2/3)_1−xO₃ (PZZN-1000x) close to x = 0.93 to 0.94 at room temperature. A new ferroelectric rhombohedral phase change, F_α–F'_α, at low temperature is found and studied by the temperature dependence of the pyroelectric coefficient. Electrical poling in these ceramics is easy, and the coercive field E_c∼8 to kV/cm is rather low. Samples with compositions in the range PZZN-86 to PZZN-92 have a large electromechanical coupling constant, k (k_t and k₁₅∼50% to 60%), and a low dielectric constant, ɛ_s (ɛ^T₃₃/ɛ₀= 260 to 320, ɛ^T₁₁/ɛ₀= 380). PZZN ceramics appear to be potential candidates for high-frequency ultrasonic transducers used in the thickness shear mode. The pyroelectric figure of merit (F_v) of these ceramics is comparable to the values published for the PZT-based or PbTiO₃-based materials.