Dielectric and piezoelectric properties of K0.47Na0.47Li0.06NbO3 doped with BaCO3 and SrCO3

A series of ceramics (1 - 2x)K0.47Na0.47Li0.06NbO3 - X(BaCO3 and SrCO3) (0 <= x <= 0.6%), were prepared by the solid state reaction method. The structures, dielectric and piezoelectric properties of the ceramics were investigated. The ceramics show pure perovskite phase with typical orthorhombic structure when x <= 0.4%. As doped with BaCO3 and SrCO3, the phase transition temperature of tetragonal -> cubic (T-c) decreases and the dielectric constant (epsilon(r)) increases, and a diffuse phase transition is induced. The ferroelectric properties (P-r and E-c). piezoelectric constant (d(33)) and electromechanical coupling factor (k(p)) increase with increasing x, and then decrease. The optimum piezoelectric properties of epsilon(r) = 570, T-c = 485 degrees C, d(33) = 235 pC/N and k(p) = 0.415 were obtained at x = 0.1%. The increase in piezoelectric properties might be due to the donor-doping of Ba and Sr. (C) 2009 Elsevier B.V. All rights reserved.