Good comprehensive performances of piezoelectric properties and thermal stabilities in 0.98(K0.50Na0.50)0.98Li0.02(Nb0.965Sb0.035)O3-0.02(Bi0.50Na0.50)HfO3 ceramics

Simultaneously achieving high piezoelectric properties and good piezoelectric thermal stabilities (of weak temperature dependence and little thermal-aging degradation) in (K,Na)NbO 3 -based ceramics is quite challenging due to the orthorhombic-tetragonal (O-T) phase transition. We have found recently an intriguing composition of 0.98(K 0.50 Na 0.50 ) 0.98 Li 0.02 (Nb 0.965 Sb 0.035 )O 3 -0.02(Bi 0.50 Na 0.50 )HfO 3 (abbreviated as KNNLS-BNH). Its ordinary ceramic shows high piezoelectric properties of d 33  = 330 pC/N, k p  = 0.52, k t  = 0.45 and k 33  = 0.65 at room temperature and considerably good piezoelectric thermal stabilities. The <00l>-textured ceramic has a highly diffused O-T phase transition, and the largely enhanced piezoelectric temperature stability in general. Specifically, the d 33 value is about 320 pC/N and remains almost unchanged over a wide temperature range from room temperature to 180 °C. It seems that the good piezoelectric thermal stabilities observed in this textured KNNLS-BNH ceramic should be ascribed to its compositional character of inherent thermal-aging stability and the highly diffused O-T phase transition.