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

Abstract A series of ceramics (1 − 2 x )K 0.47 Na 0.47 Li 0.06 NbO 3  −  x (BaCO 3 and SrCO 3 ) (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 BaCO 3 and SrCO 3 , the phase transition temperature of tetragonal → cubic ( T c ) decreases and the dielectric constant ( ɛ 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 ɛ r  = 570, T c  = 485 °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.