Microstructural features and electrical properties of copper oxide added potassium sodium niobate ceramics

In this study, effects of 0.5, 1.0 and 1.5 mole% CuO addition on the properties of potassium sodium niobate (K0.5Na0.5)NbO3-KNN ceramics were investigated. Pure KNN and CuO-added KNN pellet samples were sintered at 1100 and 1090 °C for 4 h, respectively. Phase analysis showed that all samples crystallized in pure orthorhombic perovskite phase. Addition of 1.0 and 1.5 mole% CuO caused grain growth, densification and formation of a liquid phase at the grain boundaries. Curie temperature has shifted from 480 to 435 °C with increasing CuO ratio. The most remarkable characteristic of the hysteresis loops were the constricted nature of the 0.5 mole% CuO-added KNN's curve and the antiferroelectric-like appearance of the 1.5 mole% CuO-added KNN's curve. Piezeoelectric properties of d33 = 120 pC/N, kp = 0.27 and Qm = 772 were obtained from the 1.5 mole% CuO-added KNN.