Stability And Electromechanical Properties Of PMS-PNW-PZT Piezoelectric Ceramics

Pb_1.02(Mn_1/3Sb_2/3)_0.05(Ni_2/3W_1/3)_x(Zr_0.495Ti_0.505)_0.95-xO₃(PMS-PNW-PZT)quaternary piezoelectric ceramics were prepared by conventional solid solution method. The X-ray diffraction (XRD) and the scanning electronic microscope (SEM) were applied to analyze phases and microstructure, respectively. The effects of the composition and the sintering temperature on the dielectric and piezoelectric properties and temperature stability of the system were also discussed. The study on the properties of the system doped by NiW indicated that the MPB of the tetragonal and rhombohedral phase lay in a broad composition region. The optimum properties were obtained with x=0.01at calcination temperature of 850℃and sintering temperature of 1090℃. The main parameters:ε₃₃^T/ε₀=1560, tanδ=0.5%, d₃₃=360pC/N, K_p =66.5%, Q_m=1900, T_c=287℃. Partial substitution of NiW for TiZr shifted compositions away from the tetragonal phase across the MPB toward the rhombohedral phase, greatly reduing the Curie temperature and broadening the dielectric constant maximum.In addition, The temperature coefficient of resonant frequency shifted from plus (+) into minus (-) value with increasing NiW ratio and obtained a minimum value (TKfr=1.01×10^-4/℃) at x=0.01, which reflected the transition from tetragonal phase to rhombohedral phase. The addition of NiW greatly enhanced the temperature stability of PMS–PNW–PZT system and the temperature coefficient of resonant frequency (TKfr) in the range of -25⁸0℃. When calcination temperature is 850℃and sintering temperature is 1090℃, the optimum aging properties of PMS–PNW–PZT quaternary system were obtained with x=0.01. When the temperature of aging is 100℃, aging behaviors of piezoelectric and dielectric constant follow the linear logarithmic time law,which follow the stretched exponential law with the logarithmic time while the temperature of aging is 150℃.The optimum sintering temperature(1090℃) of PMS–PNW–PZT system compared with the PMSZT system(1240℃),which showed that NiW as function of fiuxing agent play an important part to low sintering temperature.