Piezoelectric properties and thermal stability of (Na0.53K0.47−xAgx)Nb1−xSbxO3 ceramics

Abstract

AbstractMany (K1−xNax)NbO3 (KNN)‐based ceramics with high piezoelectric performance exhibit undesirable strong temperature dependence due to the orthorhombic–tetragonal polymorphic phase transition near room temperature. In order to improve the temperature stability of the ceramics, many additives have been added into the KNN‐based ceramics to shift TO–T down to below room temperature. Contrary to the previous approach (Na0.53K0.47−xAgx)Nb1−xSbxO3 (NKANS) ceramics with TO–T well above room temperature have been prepared by a conventional solid‐state reaction method. The density and the electrical properties are effectively improved by the addition of AgSbO3, and optimum piezoelectric properties are found in the ceramics with 0.05 ≤ x ≤ 0.07, with maximum kp ∼ 0.46 for NKANS5 and maximum d33 ∼ 199 pC/N for NKANS7. More importantly, kp remains virtually almost unchanged up to the TO–T temperature (≥100 °C), indicating that the NKANS ceramics exhibit a much improved piezoelectric thermal stability. The analyses suggest that both the high TO–T value and diffuse orthorhombic–tetragonal phase transition should be responsible for the good temperature stability.