Effect of Li-substitution on piezoelectric and ferroelectric properties of (Bi_0.92Na_0.92-xLi_x)_0.5Ba_0.06Sr_0.02TiO₃lead-free ceramics

New lead-free ceramics (Bi0.92Na0.92-xLix)0.5Ba0.06Sr0.02TiO3have been fabricated by a conventional ceramic technique and their electrical properties have been studied. X-ray diffraction studies reveal that Li+, Ba2+and Sr2+diffuse into the Bi0.5Na0.5TiO3lattices to form a new solid solution with a pure perovskite structure. The partial substitution of Li+for Na+increases the remanent polarization Prof the ceramics. Because of the large Prand low coercive field Ec, the ceramics with x = 0.075-0.125 exhibit excellent piezoelectric properties: d33= 189-235 pC/N, kp= 33.6-36.3% and kt= 51.6-54.3%. The ceramics exhibit relaxor behaviors after the substitution of Li+for Na+. Our results also suggest that polar and non-polar phases may coexist in the ceramics at temperatures above the depolarization temperature Td.