Energy storage and charge-discharge performance of B-site doped NBT-based lead-free ceramics

Dielectric ceramic materials with high energy-storage density and excellent charge-discharge performance are desirable for use in dielectric capacitors. In this study, (Na0.5Bi0.5)0.75Sr0.25TiO3–xNb2O5 (denoted as NBSTNx) lead-free ceramics were prepared by a solid-state reaction method. Polarization-electric field hysteresis loops (P–E loops) reflected the energy storage characteristics of the NBSTNx ceramics. Introducing Nb into a pure NBST ceramic can reduce the large remnant polarization (Pr) and make the P–E loops slimmer. Through repeated trials and calculations, the maximum recoverable energy-storage density (Wrec ~ 3.25 J/cm3) and energy storage efficiency (η ~ 74.5%) were achieved for the NBSTN0.03 ceramic at 140 kV/cm. We also tested the stability performance of the NBSTNx ceramics, where the NBSTN0.03 ceramic exhibited the highest thermal stability (30–100 °C) and frequency stability (10–1000 Hz). The NBSTN0.03 ceramic also had a fast discharge rate (<300 ns) and a good discharge energy-storage density (Wd ~ 1.80 J/cm3). Therefore, the NBSTN0.03 ceramic with a good energy-storage density and charge-discharge performance has excellent application prospects for practical dielectric capacitors.