Properties of B-site non-stoichiometric (K0.5Na0.5)(Nb0.9Ta0.1)1+xO3 lead-free piezoelectric ceramics

The non-stoichiometric (K0.5Na0.5)(Nb0.9Ta0.1)1+x O3 (x = 0, ±0.005, ±0.010) [KN(NT)1+x ] lead-free piezoelectric ceramics were prepared by normal sintering. The samples were characterized by X-ray diffraction and scanning electron microscopy. All the KN(NT)1+x ceramics possess orthorhombic perovskite structure. The grain growth of the ceramics is inhibited and the relative density is improved with increasing x. 0.5 mol% (NT)5+ excess KN(NT)1+x ceramic which sintered at 1,120 °C has the highest piezoelectric performances among with other samples. Meanwhile, the (NT)5+ excess ceramics have better time stability than the (NT)5+ deficient ones. These results show that the KN(NT)1+x ceramic with x = 0.005 is a promising lead-free piezoelectric material.