Piezoelectric properties of low-temperature sintered Li-modified (Na, K)NbO3 lead-free ceramics

LiNbO3-doped (Na, K)NbO3 lead-free piezoceramics were prepared by conventional sintering at a temperature as low as 950 degrees C using excess Na2O additives. The crystal structure changed from orthorhombic to tetragonal with increasing LiNbO3 amount since the phase transition temperature TO-T shifted downward. In the region of two-phase coexistence, enhanced piezoelectric constant d(33) (280 pC/N) and electromechanical coupling factor k(p) (48.3%) with a high Curie temperature T-C (475 degrees C) were obtained in the nominal composition 0.92(Na0.535K0.48)NbO3-0.08LiNbO(3). Our results open up the way to low-temperature sintering of (Na, K)NbO3-based lead-free piezoceramics with high performance. (c) 2008 American Institute of Physics.