Phase-composition dependent domain responses in (K0.5Na0.5)NbO3-based piezoceramics
Phase-composition dependent domain responses in (K0.5Na0.5)NbO3-based piezoceramics
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DOI：
10.1016/j.jeurceramsoc.2019.11.046
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发表时间：
2020-04-01
影响因子：
5.7
通讯作者：
Tan, Xiaoli
中科院分区：
文献类型：
--
作者：
Fan, Zhongming;Zhang, Shujun;Tan, Xiaoli
据报道，室温下在正交相和四方相之间具有多晶相界（PPB）的无铅（K0.5Na0.5）NbO3基（KNN）压电陶瓷具有高压电性能，但循环稳定性较差，而单四方相陶瓷表现出改善的循环稳定性，但压电系数较低。在这项工作中，对两种基于 KNN 的组合物进行了电偏压原位透射电子显微镜 (TEM) 研究，它们分别处于 PPB 和非 PPB 状态。我们的观察揭示了这两种陶瓷在循环场下的独特域响应。 PPB 下极化 KNN 中较高的磁畴壁密度有助于提高压电性能。然而，在循环时，可以在这种 PPB 组合物中直接观察到一种新的微观结构特征，即“域交叉”。相比之下，非 PPB KNN 陶瓷在极化过程中会形成较大的区域，在循环过程中受到的破坏程度要小得多。我们的比较研究为理解相组成和压电性能之间的关系提供了基础。
Lead-free (K0.5Na0.5)NbO3-based (KNN) piezoceramics featuring a polymorphic phase boundary (PPB) between the orthorhombic and tetragonal phases at room temperature are reported to possess high piezoelectric properties but with inferior cycling stability, while the ceramics with a single tetragonal phase show improved cycling stability but with lower piezoelectric coefficients. In this work, electric biasing in-situ transmission electron microscopy (TEM) study is conducted on two KNN-based compositions, which are respectively at and off PPB. Our observations reveal the distinctive domain responses in these two ceramics under cyclic fields. The higher domain wall density in the poled KNN at PPB contributes to the high piezoelectric properties. Upon cycling, however, a new microstructure feature, "domain intersection", is directly observed in this PPB composition. In comparison, the off-PPB KNN ceramic develops large domains during poling, which experience much less extent of disruption during cycling. Our comparative study provides the basis for understanding the relation between phase composition and piezoelectric performance.