Utilization of Nonstoichiometric Nb<sup>5+</sup> to Optimize Comprehensive Electrical Properties of KNN-Based Ceramics
Hongjiang Li, Lixu Xie, Zhi Tan, Jie Xing, Xu Li, Hao Chen, Fei Wang, Yuan Cheng, Manjing Tang, Jianguo Zhu
Abstract
An easy approach is suggested to obtain excellent piezoelectric performances in potassium sodium niobate (KNN)-based ceramics simultaneously with low dielectric loss (tanδ), high Curie temperature (TC), and electromechanical coupling factor (kp). Herein, a KNN-based ceramics system with nonstoichiometric Nb5+ is designed. Excessive Nb5+ occupying the B-site significantly influences the microstructural features and electrical properties of KNN-based ceramics. Furthermore, the excessive Nb5+ improves the temperature stability of ceramics by providing the domain wall pegging effect and defect dipole. A high TC = 300 °C, large kp = 0.516, and d33 = 450 pC/N can be simultaneously obtained in the KNN-based ceramics with nonstoichiometric Nb5+. These results confirm that the comprehensive electrical properties of KNN-based ceramics can be tuned by optimizing the content of nonstoichiometric Nb5+.