BNT-BKT-BiCrO_3压电陶瓷的压电性能和退极化温度

Piezoelectric properties and depolarization temperature of the lead-free piezoelectric ceramics of BNT-BKT-BiCrO_3

采用传统陶瓷制备方法，制备了一种新型无铅压电陶瓷材料（1-x-y）Bi0．5Na0．5TiO3-xBi0．5K0．5Ti03-yBiCrO3（简写为BNT-BKT—BC—x／y）．研究了该体系陶瓷微观结构、压电性能和退极化温度的变化规律．结果表明：除x=0．18、y=0．025的组成析出第2相外，其他组成陶瓷均能够形成纯钙钛矿固溶体，陶瓷三方、四方共存的准同型相界（MPB）成分范围为．27=0．18～0．21，y=0～0．02．在准同型相界成分附近该体系陶瓷压电性能达到最大值：d33=168pC·N^-1，kp=0．326．采用平面机电耦合系数kp和极化相位角θmax与温度的关系确定的退极化温度基本相同，陶瓷的退极化温度随BC含量的增加一直降低。随BKT含量的增加先降低后升高．

A （Bi0.5Na0.5）TiO3-based lead-free piezoelectric ceramic, （1 - x - y）Bi0.5Na0.5TiO3-xBi0.5K0.5TiO3-yBiCrO3（BNT-BKT-BC-x/y）, was prepared by a conventional ceramic sintering technique. Its crystal structure, and piezoelectric properties and depolarization temperature were investigated. The morphotropic phase boundary （MPB） of the system between rhombohedral and tetragonal locates in the range of x = 0.18 to 0.21 and y = 0 to 0.02. Moreover, an obvious second phase was observed in the samples with y = 0. 025 and x = 0.18. The optimum piezoelectric properties were obtained near the MPB composition, and the piezoelectric constant d33 and the electromechanical coupling factor k p of the ceramics attain the maximum values of 168 pC·N^-1 and 0. 326 at x = 0.18, y=0.015 and at x = 0.18, y = 0.01, respectively. The depolarization temperatures confirmed by kp and θmax are almost identical. The depolarization temperature keeps decreasing with an increase content of BC and first increases and then decreases with an increase content of BKT.