High temperature stable dielectric properties and enhanced energy-storage performance of (1-x)(0.85Na(0.5)Bi(0.5)TiO(3)-0.15Ba(0.8)Ca(0.2)Ti(0.8)Zr(0.2)O(3))-xK(0.5)Na(0.5)NbO(3) lead-free ceramics

摘要

Novel high temperature ceramic capacitors (1 - x)(Na0.5Bi0.5TiO3 - 0.15Ba(0.8)Ca(0.2)Ti(0.8)Zr(0.2)O(3))-xK(0.5)Na(0.5)NbO(3) were synthesized in the solid-state reaction route. The influence of K0.5Na0.5NbO3 modification on dielectric behavior, energy-storage properties, ac impedance and temperature stable dielectric performance were systematically investigated. The reduced grain size and enhanced relaxor properties are obtained with the addition of KNN. The content of x = 0.1 exhibits a stable permittivity (similar to 1630) and dielectric loss ( 0.05) over a relatively broad temperature range (66-230 degrees C). A variation in permittivity within +/- 15% can be observed over a pretty wide temperature range of 66-450 degrees C. Beyond that, this ceramic shows enhanced energy-storage properties with the density (W-rec) of 0.52 J/cm(3) and efficiency (eta) of 80.3% at 110 kV/cm. The possible contributions of the grain and the grain boundary to the ceramic capacitance are discussed by the ac impedance spectroscopy.