无铅压电陶瓷K0.5Na0.5NbO3-BiFeO3的烧结工艺与压电性能研究

采用传统常压固相烧结工艺制备了掺杂0.8at%BiFeO₃(BF)的K_0.5Na_0.5NbO₃(KNN) 无铅压电陶瓷,着重研究了烧结温度与保温时间对陶瓷的晶体结构、相转变、致密度与压电、介电性能的影响. 研究结果表明, 所有陶瓷样品都为单一的钙钛矿结构, 烧结温度与保温时间对陶瓷样品的室温晶体结构与相转变温度几乎没有影响, 但对陶瓷的表面形貌、密度和压电性能有较大的影响. 当保温时间为3h，在1100℃至1150℃范围内, 随烧结温度的升高，陶瓷的压电常数d33、平面机电耦合系数Kp及机械品质因数Qm均一直升高, 介电损耗tanδ则显著降低. 当烧结温度为1150℃时, 随保温时间的增加, 陶瓷的压电性能先显著提高后基本保持不变. 1150℃保温2h烧结的陶瓷获得良好的性能：密度ρ=4.50g/cm³（致密度为95.63%）, d₃₃=132pC/N, K_p=45%, Q_m=333.73, tanδ=2.39%.

Sintering Processing and Piezoelectric Properties of K_(0.5)Na_(0.5)NbO_3-BiFeO_3 Lead-free Ceramics

Lead-free BiFeO_3 (BF) doped K_(0.5)Na_(0.5)NbO_3 (KNN) piezoelectric ceramics were prepared by a traditional ceramic processing. The effects of sintering temperature and holding time on the microstructure, phase transition, density and piezoelectric properties of BF doped KNN ceramics were investigated. The results show that all specimens exhibit a pure perovskite structure. The surface micrograph, density and piezoelectric properties of the ceramics depend strongly on the sintering temperature and holding time. When being sintered at temperature from 1100℃ to 1150℃ for 3h, the d_(33), K_p and Q_m of the ceramics increase, while the tanδ decreases with the sintering temperature increasing. When being sintered at 1150℃ for 1h to 3h, the d_(33), K_p and Q_m of the ceramics increase firstly and then remain unchanged, while the tanδ decreases firstly and then also remains unchanged with the holding time increasing. The BF-doped KNN ceramics sintered at 1150℃ for 2h exhibit excellent properties (ρ=4.50g/cm~3, d_(33)=132pC/N, K_p=45%, Q_m=333.73 and tan δ=2.39%).