Microstructure, crystalline phase and electrical properties of Li0.06(Na0.5K0.5)0.94Nb(1-2x/5)MgxO3

MgO-modified Li0.06(Na0.5K0.5)0.94NbO3 (L6NKN) lead-free piezoelectric ceramics were synthesized by normal sintering at a rela-tively low temperature of 1000℃. The crystalline phase, microstructure, and electrical properties of the ceramics were investigated with a special emphasis on the influence of MgO content. The addition of MgO effectively improves the sinterability of the L6NKN ceramics. X-ray diffraction analysis indicates that the morphotropic phase boundary (MPB) separating orthorhombic and tetragonal phases for the ceramics lies in the range of Mg doping content (x) from 0.3at% to 0.7at%. High electrical properties of the piezoelectric constant (d33=238 pC/N), planar electromechanical coupling coefficient (Kp=41.5%), relative dielectric constant (εr=905), and remanent polarization (Pr=38.3μC/cm2) are obtained from the specimen with x=0.5at%, which suggests mat the Li0.06(Na0.5K0.5)0.94Nb(1-2x/5)MgxO3 (x=0.5at%) ceramic is a promising lead-free piezoelectric material.