BiCoO₃-doped (K_0.475Na_0.475Li_0.05)(Nb_0.8Ta_0.2)O₃ lead-free piezoelectric ceramics

Abstract

(1--x)(K_0.475Na_0.475Li_0.05)(Nb_0.8Ta_0.2)O₃--xBiCoO₃ (KNLNT--BC) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, microstructure and electrical properties of KNLNT--BC ceramics were investigated. XRD patterns reveal that all the ceramic samples are in the pure perovskite-type structure, and the phase structure changes from the tetragonal to pseudo-cubic phase with the increase of the BC content. After the substitution of BC, the grain size is significantly reduced and relaxer behaviors are induced. By adding a small amount of BC to KNLNT ceramics, piezoelectric properties are improved, while further addition of BC makes the piezoelectric properties deteriorate markedly. The optimized electrical properties at x = 0.005 are as follows: d₃₃ = 194 pC/N, k_p = 0.44.

Keywords

lead-free ceramic / potassium sodium niobate / BiCoO₃ / piezoelectric property