xPb(Mg_(1/3)Nb_(2/3))O_3–(1–x)Pb(Zr_(0.48)Ti_(0.52))O_3压电陶瓷的准同型相界与介电性能

THE MORPHOTROPIC PHASE BOUNDARY AND DIELECTRIC PROPERTIES OF xPb(Mg_(1/3)Nb_(2/3))O_3-(1-x)Pb(Zr_(0.48)Ti_(0.52))O_3 PIEZOELECTRIC CERAMICS

采用铌铁矿预产物合成法制备组成在准同型相界(morphotropic phase boundary,MPB)附近的xPb(Mg1/3Nb2/3)O3-(1-x)Pb(Zr0.48Ti0.52)O3(PMN-PZT,x=0.125,0.15,0.175,0.2,0.225,0.25,摩尔分数)压电陶瓷。X射线衍射和Raman光谱分析表明:所有陶瓷样品的相组成均为纯钙钛矿相,未探测到其他杂相;随PMN含量的增加,PMN-PZT压电陶瓷的相结构从四方相逐渐向菱方相转变,该体系的MPB组成在x=0.2附近,而且其相结构为四方相与菱方相共存。陶瓷断口的扫描电镜观察表明:陶瓷的晶粒尺寸约1～3μm。陶瓷的介电温谱表明:x=0.2,陶瓷的Curie温度为308.8℃,峰值介电常数约为16380,室温压电常数为351pC/N;陶瓷的Curie温度随PMN含量增加线性下降。

Piezoelectric ceramics xPb（Mg1/3Nb2/3） O3–（1–x） Pb（Zr0.48Ti0.52） O3（PMN–PZT,x=0.125,0.15,0.175,0.2,0.225,0.25,mole fraction） near the morphotropic phase boundary（MPB） were prepared using the columbite precursor method.A single perovskite phase was identified by the X-ray diffraction and Raman spectra results for all specimens.The phase transition from tetragonal to rhombohedra was also observed with increasing PMN mole fraction.The coexistence of the tetragonal and rhombohedral phases is identified near the 0.2PMN–0.8PZT composition,clearly implying that the MPB of this PMN–PZT system lies near the x=0.2 composition.The grain size is about 1–3μm judging by the scanning electronic microscope photographs of the fracture face.The temperature dependence of the di-electric constant illustrates that the Curie temperature descends linearly with the content of PMN increases.For x=0.2,the maximum value of dielectric constant is 16 380 at the Curie temperature of 308.8℃,and the piezoelectric constant is 351 pC/N.