Temperature stability of multilayer symmetric KNN-based ceramics with continuous phase transitions

Temperature sensitivity of the lead-free piezoelectric ceramics based on potassium sodium niobate (KNN) has posed a significant challenge for practical applications. In this study, we developed a multi-layer symmetric KNN matrix composite ceramic in a strategy of compositional symmetry to enhance the thermal stability of its piezoelectric properties. The optimized piezoelectric properties of d33 and kp can last up to 121 and 105 °C (setting 10% performance reduction as standard), superior to its single composition sample. Importantly, the compositional symmetry effectively addresses the deformation issue during ceramic sintering. This finding of stability in KNN matrix ceramics will facilitate its industrial-scale production processes.