Electromechanical and dielectric properties of Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3-BaTiO3

Electromechanical and dielectric properties of (1-3x)NBT-2x KBT-xBT lead-free ceramics were investigated. XRD results show that the crystalline structure of the ceramics was perovskite. The morphotropic phase boundary (MPB) of the ternary system between rhombohedral and tetragonal locates in the range of x = 0.025-0.035. The preferred piezoelectric constant d(33) = 150 pC N-1 and planar electromechanical coupling factor k(p) = 0.298 are observed at x = 0.035, corresponding to a relatively large remanent polarization of P-r = 35.0 mu C cm(-2) and a relatively low coercive field of E-c = 4.55 kV mm(-1). Temperature dependence of dielectric constant at different frequencies shows that the ferroelectric characteristic of (1-3x)NBT-2xKBT-xBT lead-free ceramics transforms from relaxor ferroelectric to normal ferroelectric with increasing of KBT and BT concentration. (c) 2005 Elsevier B.V. All rights reserved.