Effect of LiSbO₃ and SrZrO₃ doping on the piezoelectric properties and microstructural behavior of K_0.5Na_0.5NbO₃ ceramics

The effect of LiSbO₃ and SrZrO₃ doping on the piezoelectric characteristics of K_0.5Na_0.5NbO₃-based ceramics was studied. First, (1 − x)K_0.5Na_0.5NbO₃–xLiSbO₃–CuO (0.00 ≤ x ≤ 0.07) was synthesized and a single phase of perovskite was observed in the range of 0.00 ≤ x ≤ 0.05. As LiSbO₃ content increased, the orthorhombic single phase changed to orthorhombic and tetragonal multiphase. T_O–T decreased from 176 °C (x = 0.00) to 85 ℃ (x = 0.05) and, the d₃₃ showed the highest value of 156 pC/N (x = 0.05). Next, (0.95K_0.5Na_0.5NbO₃–0.05LiSbO₃)–xSrZrO₃–CuO (0.00 ≤ x ≤ 0.05) was studied. All compositions were well synthesized as perovskite phases; orthorhombic and tetragonal mixed phases up to x = 0.02, rhombohedral, orthorhombic, and tetragonal mixed phases at x = 0.03 and 0.04; and rhombohedral and tetragonal phases at x = 0.05. T_O–T decreased from 78 ℃ (x = 0.00) to 32 ℃ (x = 0.04), and T_R–T was formed at 48 ℃ (x = 0.05). The d₃₃ value at x = 0.04 was 288 pC/N and significantly reduced to 134 pC/N at x = 0.05.