Study on PSN-PZN-PZT quaternary piezoelectric ceramics near the morphotropic phase boundary

Pb(Sn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbZrO3-PbTiO3 quaternary piezoelectric ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared by conventional solid solution method. The phase structure, the piezoelectric and dielectric properties of the system were investigated. X-ray diffraction patterns indicated that the MPB of the tetragonal and rhombohedral phase lay in a broad composition region. The properties optimized for high-power applications such as transformers, ultrasonic motors, and electromechanical transducers were obtained with Zr/Ti=44/44 at calcination temperature of 960oC and sintering temperature of 1260oC. The main parameters: ε33T/ε0=1665, d33=314pC/N, Kp=57.8%, Qm=2614, tanδ=0.4%, Tc=279oC. The temperature coefficient of resonant frequency shifted from plus (+) into minus (-) value with increasing Zr/Ti ratio and obtained a minimum value (Δfr/fr25oC=0.67%) at Zr/Ti=44/44, which reflected the transition from tetragonal phase to rhombohedral phase