Significant improvement in electrical characteristics and energy storage performance of NBT-based ceramics

Abstract

Dielectric capacitors with superior power density and ultra-fast charge/discharge capability have attracted growing attention in the pulse power field. In this work, rare earth oxide (Sm2O3) was introduced into (0.74Na0.5Bi0.5-0.26Sr)Ti0.9Zr0.1O3 matrix, to enhance the comprehensive energy storage performance. The structure, dielectric and ferroelectric characteristics of these materials were systematically studied, to assess the potential application in multilayer ceramic capacitors. All samples yielded a perovskite structure, as the addition of Sm2O3 results in a substantial increase in density, along with the enhancement of relaxor behavior and local nanodomains. With increasing Sm2O3 concentration, a distinctly slim ferroelectric hysteresis loop as well as frequency dispersive dielectric characteristics have been detected. The NBSZT-0.02Sm ceramic has realized an excellent energy storage density of 4.62 J/cm3, with a moderately good energy efficiency of 84.38% and favorable temperature stability over a broad temperature range of 102.7–397.1 °C. The activation energy (Ea) of the ceramics increased from 1.40 eV to 1.72 eV with Sm2O3 concentration increasing from x = 0 to x = 0.04, which inhibits the appearance of the local electrical branch and thus improves the breakdown strength of the NBSZT-xSm ceramics. This study provides a novel possibility for designing lead-free ceramic materials for high-temperature capacitors.