| Pb(Sn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbZrO3-PbTiO3 (PSN-PZN-PZT) quaternary piezoelectric ceramics were prepared by conventional solid solution method. The samples were gained by adding MnO2, Sb2O3, Cr2O3, SrCO3 and BaCO3 in order to enhance the properties. 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 Cr indicated that the MPB of the tetragonal and rhombohedral phase lay in a broad composition region. The optimum properties were obtained with Zr/Ti=44/44 at calcination temperature of 960℃and sintering temperature of 1260℃. The main parameters:ε33T/ε0=1665, tanδ=0.4%, d33=314pC/N, Kp =57.8%, Qm=2614, Tc=279℃. The temperature coefficient of resonant frequency shifted from plus (+) into minus (-) value with increasing Zr/Ti ratio and obtained a minimum value (TKfr=1.1×10-4/℃) at Zr/Ti=44/44, which reflected the transition from tetragonal phase to rhombohedral phase.In addition, PSN-PZN-PZT quaternary system doped by Sr, Ba close to the the morphotropic phase boundary (MPB) were investigated systematically as a function of Sr doping and Zr/Ti ratio. Partial substitution of Sr for Pb shifted compositions away from the rhombohedral phase across the MPB toward the tetragonal phase, greatly reduing the Curie temperature and broadening the dielectric constant maximum. When calcination temperature is 960℃and sintering temperature is 1260℃, the optimum properties ofε33T/ε0 (1381), tanδ(0.4%), d33 (295pC/N), Kp(61.5%), Qm(1447), Tc(254℃) were obtained with Sr=0.02 and Zr/Ti=44/44. The addition of Sr greatly enhanced the temperature stability of PSN-PZN-PZT system and the temperature coefficient of resonant frequency (TKfr) in the range of -2580℃is 3.0×10-5/℃.
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