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

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 (Sm 2 O 3 ) was introduced into (0.74Na 0.5 Bi 0.5 -0.26Sr)Ti 0.9 Zr 0.1 O 3 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 Sm 2 O 3 results in a substantial increase in density, along with the enhancement of relaxor behavior and local nanodomains. With increasing Sm 2 O 3 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/cm 3 , 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 ( E a ) of the ceramics increased from 1.40 eV to 1.72 eV with Sm 2 O 3 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- x Sm ceramics. This study provides a novel possibility for designing lead-free ceramic materials for high-temperature capacitors.