Ti/Ba摩尔比对准同型相界组成BiFeO_3-BaTiO_3高温陶瓷微观结构和电性能的影响

Effect of Non-Stoichiometric Ti/Ba Mole Ratio on Microstructure and Electrical Properties of BiFeO_3-BaTiO_3 High-Temperature Ceramic Near Morphortropic Phase Boundary

为了建立A、B位非化学计量与压电介电性能的联系,进而对材料性能的演变作出准确的预测和判断,研究了Ti/Ba摩尔比(x)对BiFeO3-BaTiO3(BF-BT)高温压电陶瓷在准同型相界(MPB)附近的组分0.70BF-0.30BT(BFBT-xTi,其中x=0.980、0.985、0.990、0.995、1.000、1.010)微观结构与电性能的影响。结果表明,随着摩尔比x的变化,所有组成均为纯钙钛矿结构固溶体,Ti不足时晶体结构出现明显三方畸变,促进晶粒生长,但是过量的Ti抑制晶粒生长。压电常数d33、机电耦合系数kp随着x的增加先增加后减少,在x=0.99时压电性能达到最大值:d33=152pC/N,kp=0.301。退极化温度Td随x的增加一直降低,适量Ti不足有利于提高压电性能的温度稳定性。

To establish a correlation between A, B-site non-stoichiometric and piezoelectric, dielectric properties, and predict the evolution of properties with composition, the effect of non-stoichiometric Ti/Ba mole ratio（x） on the mierostructure and electrical properties for high-temperature piezoelectric ceramics BiFeO3-BaTiO3 （BF-BT） near the morphortropic phase boundary （MPB） composition of 0. 70BF-0. 30BT（BFBT-xTi, x = 0. 980,0. 985,0. 990,0. 995,1. 000, 1. 010） was investigated. The a- nalysis by X-ray diffraction shows that all the samples have a single perovskite phase when x increases, and the rhombohedral distortion degree increases for titanium deficiency BFBT-xTi ceramics. The deficiency of titanium promotes the growth of grains, but the excess titanium suppresses the growth of grains. The piezoelectric constant （d33） and the planar electromechan- ical coupling factor （kp） firstly increase and then decrease with increasing x, giving the optimum values （d33 = 152 pC/N and kv = 0.301） for x = 0. 99 BFBT-xTi ceramic. The depolarization temperature （Td） decreases monotonically with increasing x, and moderation titanium deficiency was favor to improve the temperature stability of piezoelectric properties.