Bi0.5(Na1-x-yKxLiy)0.5TiO3陶瓷的介电性能与微观结构

利用传统陶瓷工艺制备了新型的Bi0.5(Na1-x-yKxLiy)0.5TiO3无铅压电陶瓷,研究了陶瓷的介电性能和微观结构。研究结果表明,介电常数εr和介质损耗tgδ在K含量为0.20~0.25(摩尔分数)时达到最大值,且随Li含量的增加而增大;介温曲线表明,Bi0.5(Na1-x-yKxLiy)0.5TiO3陶瓷在110~210℃之间出现介质损耗峰,在300~350℃附近出现比较平坦的介电常数峰;陶瓷的最佳烧结条件为1 100~1 150℃,2~3 h;陶瓷晶粒有规则的几何外形,晶粒尺寸为1.2~2.5 m;Li含量越高,陶瓷的烧结温度越低;K促进了晶粒特定方向的生长。

Studies on Dielectric Properties and Microstructures of Bi0.5(Na1-x-yKxLiy)0.5TiO3 Piezoelectric Ceramics

Lead-free piezoelectric ceramics Bi0.5(Na1-x-yKxLiy)0.5TiO3 were prepared by the conventional ceramic sintering technique. The dielectric properties and the microstructures of these piezoelectric ceramics were also studied. The measurement results of the dielectric properties reveal that the dielectric constants and the dielectric losses of the materials reach a maximum at x=0.20~0.25, the dielectric constants and the dielectric losses increase with y increasing, and the dielectric constant peaks appear in the temperature of 300~350℃ in the dielectric constant - temperature curves. And the dielectric loss peaks appear in the temperature of 120~200℃ in the dielectric loss-temperature curves. It is found that the optimized sintering condition is at 1 100~1 150℃, 2~3 h, the grains of the ceramics have very regular shape, the grain size of the ceramics is in the range of 1.2~2.5 μm. The ceramics of high Li concentration have lower sintering temperature, and K promotes the growth in some directions of crystalline grains.