Piezoelectric properties and thermal stability of (Na 0.53K 0.47-xAg x)Nb 1-xSb xO 3 ceramics

Abstract

Many (K 1-xNa x)NbO 3 (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 T O-T down to below room temperature. Contrary to the previous approach (Na 0.53K 0.47-xAg x)Nb 1-xSb xO 3 (NKANS) ceramics with T O-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 AgSbO 3, and optimum piezoelectric properties are found in the ceramics with 0.05 ≤x≤ 0.07, with maximum k p ∼ 0.46 for NKANS5 and maximum d 33 ∼ 199 pC/N for NKANS7. More importantly, k p remains virtually almost unchanged up to the T O-T temperature (≥100 °C), indicating that the NKANS ceramics exhibit a much improved piezoelectric thermal stability. The analyses suggest that both the high T O-T value and diffuse orthorhombic-tetragonal phase transition should be responsible for the good temperature stability. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.