Properties of B-site non-stoichiometric (K_(0.5)Na_(0.5))(Nb_(0.9)Ta_(0.1))_(1+x)O_3 lead-free piezoelectric ceramics

摘要

The non-stoichiometric (K_(0.5)Na_(0.5))(Nb_(0.9)Ta_(0.1))_(1+x)O_3 (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 ℃ 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.