Piezoelectric and dielectric properties of (Na0.5K 0.5)NbO3-Bi0.5(Na0.8K 0.2)0.5TiO3 lead-free ceramics

Abstract

Lead-free piezoelectric ceramics (1-x)(Na0.5K 0.5)NbO3-xBi0.5(Na0.8K 0.2)0.5TiO3 (abbreviated as NKN-BNKT100x, with x ranges from 0 to 0.08 mol) have been synthesized by a conventional solid state sintering method. The effects of amount of BNKT-content on electrical properties and crystalline structures have been investigated. X-ray diffraction analysis showed that a morphotropic phase boundaries (MPB) between orthorhombic and tetragonal phases exists in the composition range of 0.05 < x < 0.06, near which the dielectric and piezoelectric properties are enhanced. The NKN-BNKT5 ceramics exhibits good properties (d33 = 216pC/N, k p = 41%, ε33T/ε0= 1315). These results indicate that NKN-BNKT 100x ceramic is a promising lead-free piezoelectric candidate material. ©2008 The Ceramic Society of Japan. All rights reserved.