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 d(33) 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)O-3 ceramics possess excellent piezoelectric properties of d(33)=300 pC/N, k(p)=0.493, and k(33)=0.651 with tan delta=0.011, and its k(p) remains larger than 0.40 in the broad temperature range from -43 to 73 degrees C and is almost constant between -25 and 55 degrees C. The results indicate that CuO-modified Ba(Ti,Zr)O-3 ceramics are a promising low-cost lead-free material for practical applications.