Enhanced thermal reliability of Mn-doped (K, Na)NbO₃-based piezoelectric ceramics

Improving temperature stability of (K, Na)NbO₃-based ceramics can facilitate their development in practical application. In this work, 0.5 mol% Mn elements doped 0.95(Na_0.5K_0.5)NbO₃–0.05(Bi_0.5Na_0.5)HfO₃ (abbreviated as KNN) piezoelectric ceramics are reported. Permittivity–temperature curves reveal that the Mn-doped ceramics have higher Curie temperature and more dispersive orthorhombic–tetragonal phase transition compared with undoped ceramics, which improves the temperature stability of the KNN-based ceramics. The electric-field-induced strain varies less than 22% over a wide temperature range from 20 to 200 °C for the Mn-doped KNN-based ceramics, which is much better than the undoped KNN-based ceramics (variation: 38%). Therefore, our work provided a new promising candidate for temperature-insensitive piezoelectric ceramic devices.