Effect of sintering temperature on phase structure, microstructure, and electrical properties of (K0.5Na0.5)NbO3–(Ba0.6Sr0.4)0.7Bi0.2TiO3 lead-free ceramics

Lead-free 0.98(K0.5Na0.5)NbO3–0.02(Ba0.6Sr0.4)0.7Bi0.2TiO3 (abbreviated as 0.98KNN–0.02BSBT) ceramics were prepared by the conventional solid-state sintering method. Effect of sintering temperature on 0.98KNN–0.02BSBT ceramics was systematically investigated. The frequency dependent dielectric permittivities show that the ceramics sintered at different temperatures are indeed “relaxor-like” ferroelectric ceramics, which possess a diffuse phase transition without a strong frequency dispersion of dielectric permittivity. The diffuseness parameter γ, the comparison of the relaxor behavior based on empirical parameters (ΔTdiffuse) and the slimmer P–E hysteresis loops confirm that the “relaxor-like” characteristics of the ceramics are strengthened with increasing sintering temperature. At the optimum sintering temperature, the dielectric permittivity maximum (ɛmax) has a value of approximately 2795 (at 1 KHz), tanδ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \tan \delta $$\end{document} is lower than 2.5 % and the diffuseness parameter γ = 1.68 at a broad usage temperature range (150–350 °C), which indicate its potential application in high temperature multilayer ceramics capacitor field.