0．98Bi0．5（Na0．82 K0．18）0．5 TiO 3-0．02NaNbO 3无铅压电陶瓷的烧结工艺及性能研究∗

摘要

0.98Bi0.5 (Na0.82 K0.1 8 )0.5 TiO 3-0.02NaNbO 3 lead-free piezoelectric ceramics were prepared by solid state reaction method.The effect of sintering process on the phase,microstructure and electric-properties were stud-ied.The results show the calcinated powder was perovskite structure at 900 ℃.The crystal structure was not changed with the sintering process beginning.The grain size increases with sintering temperature increasing, but glass phase appears in the system because of high sintering temperature.The excellent electric properties ofεr=1 620,tanδ=0.030,d 3 3 =138 pC/N,k p =0.40 are obtained at 1 200 ℃.The lowest Curie temperature of 370 ℃ was tested at 1 200 ℃ and the curie temperature was enhanced without sintering temperature was higher or lower than 1 200 ℃.The dielectric constant was deceased with the frequency increasing.The space charge po-larization loss contribution around 150 kHz at the range of 300 Hz-700 kHz,and the dielectric constant changes very small when the frequency was more than 150 kHz.%采用固相反应方法制备0．98Bi0．5(Na0．82 K0．18)0．5 TiO 3-0．02NaNbO 3无铅压电陶瓷.研究该体系陶瓷的烧结工艺对压电陶瓷的物相、显微结构及电性能的影响.结果表明,900℃合成温度下,合成粉料为 ABO 3型钙钛矿结构,烧结温度变化不会使晶体结构发生改变.随着烧结温度增加,晶粒尺寸变大,陶瓷致密性提高,但过高的烧结温度使体系中出现玻璃相.电性能表明,1200℃烧结温度下,压电陶瓷的电性能最佳：εr ＝1620、tanδ＝0．030、d 33＝138 pC/N、k p ＝0．40.居里温度在1200℃时最低,T C ＝370℃,烧结温度降低或升高,都会使居里温度增加.在300 Hz~700 kHz 的频率范围内,150 kHz 左右空间电荷极化失去贡献,之后介电常数趋于稳定.