Excellent temperature stability, high relative permittivity, and piezoelectric properties of K0.5Na0.5NbO3–Bi(Li1/3Ti2/3)O3 lead-free ceramics

Abstract

(1 − x)K0.5Na0.5NbO3–xBi(Li1/3Ti2/3)O3 [(1 − x)KNN–xBLT, x = 0, 0.005, 0.01, 0.015, 0.02] ceramics were prepared via a solid-state reaction method. The sintering behavior, phase structure, dielectric properties, piezoelectric performances and conductive behavior of ceramics were investigated. The BLT additive could effectively improve the performances of KNN ceramics. When x = 0.01, piezoelectric constants d33 of 145 pC/N, relative permittivity er of ~ 1551, temperature stability (Δe/e110 °C) of ± 9% (110–330 °C), dielectric loss tanδ ≤ 0.036 (101.5–388 °C) were obtained. The values of activation energy E rel and electrical conductivity activation energy E con changed from 1.1572 to 1.5918 eV and 0.8959 to 1.1088 eV, respectively. Furthermore, a possible mechanism of high temperature dielectric relaxation and conductivity could be attributed to the oxygen vacancy defect of secondary ionization.