Piezoelectric properties and stabilities of CuO-modified Ba(Ti,Zr)O3 ceramics

Due to the orthorhombic-tetragonal polymorphic phase transition near room temperature, undesirable large temperature dependence of piezoelectric properties is observed over common usage temperature range in BaTiO3 ceramics with high d33 values. Whereas shifting the phase transition temperature upward by partially substituting Ti with Zr is effective in reducing the piezoelectric temperature dependence, serious long-term degradation occurs. However, it is found that this could be overcome by incorporating a small amount of CuO additive. CuO-modified Ba(Ti0.9625Zr0.0375)O3 ceramics possess excellent piezoelectric properties of d33=300 pC/N, kp=0.493, and k33=0.651 with tan δ=0.011, and its kp remains larger than 0.40 in the broad temperature range from −43 to 73 °C and is almost constant between −25 and 55 °C. The results indicate that CuO-modified Ba(Ti,Zr)O3 ceramics are a promising low-cost lead-free material for practical applications.