Piezoelectric and ferroelectric properties of [Bi0.5(Na1-x-yKxLiy)0.5]TiO3 lead-free piezoelectric ceramics

The piezoelectric and ferroelectric properties of [Bi-0.5(Na1-x-yKxLiy)(0.5)]TiO3 (BNKLT-x/y) lead-free piezoelectric ceramics were studied. The ceramics show excellent piezoelectric and ferroelectric properties, and the optimum properties measured are as follows: piezoelectric constant d(33)=231 pC/N, planar and thickness electromechanical coupling factors k(P)=41.0% and k(t)=50.5%, remanent polarization P-r=40.2 mu C/cm(2), and coercive field E-c=2.47 kV/mm, respectively. Polarization versus electric (P-E) hysteresis loops of the ceramics are well rectangle shaped, and the dependence of P-E loops on temperature reveals that the depolarization temperature T-d of BNKLT-0.15/0.075 ceramics, which simultaneously have good piezoelectric properties (d(33)=164 pC/N,k(p)=36.3%,k(t)=48.6%) and strong ferroelectricity (P-r=38.8 mu C/cm(2),E-c=3.73 kV/mm) at room temperature, is about 195 degrees C. (c) 2006 American Institute of Physics.