Effects of annealing temperature on the properties of potassium sodium niobate films grown by RF magnetron sputtering

Abstract

Potassium sodium niobate (KNN) is considered a promising alternative to conventional lead-based piezoelectric materials due to its high piezoelectric performance and environmental friendliness. However, owning to the volatility of alkali elements, the fabrication of KNN materials, especially thin films, remains challenging. This study employs the magnetron sputtering to deposit KNN thin films and systematically investigates the phase evolution and physical property variations under different annealing temperatures. The results indicate that under atmospheric annealing conditions, secondary phases appear in the films when annealed below 660°C, while over-sintering effects lead to a decline in crystallinity when annealed above 680°C. The films annealed at 670°C exhibit the optimal piezoelectric response. An appropriate annealing temperature range is crucial for optimizing phase purity and crystal quality, providing guidance for the fabrication of high- performance KNN thin films.