Energy storage performance of Na0.5Bi0.5TiO3-SrTiO3 lead-free relaxors modified by AgNb0.85Ta0.15O3

Exploring eco-friendly energy-storage ceramics simultaneously featuring large recoverable energy storage density (W-rec), high energy storage efficiency (eta), and excellent temperature/frequency stabilities is highly desirable for the applications of pulsed power systems. Herein, AgNb0.85Ta0.15O3 was used to modify Na0.5Bi0.5TiO3 based lead-free relaxor ferroelectric ceramics in an effort to enhance the breakdown electric field strength. The ceramics (1-x)(0.75Na(0.5)Bi(0.5)TiO(3)-0.25SrTiO(3))-xAg(Nb0.85Ta0.15)O-3 (x = 0, 0.05, 0.1, and 0.15) were prepared by the conventional solid-state reaction method. The microstructure, dielectric, and energy storage properties of all the ceramics have been systematically studied. Our results show that the introduction of AgNb0.85Ta0.15O3 leads to a homogeneous microstructure and small grain size, thereby increasing the strength of the dielectric breakdown field (29 kV/mm). In addition, it can also decompose the macroscopic long-range ferroelectric order into randomly-oriented polar nano-regions (PNRS), resulting in a board diffusive phase. A large W-rec (3.6 J/cm(3)) and high eta (80%) as well as excellent temperature and frequency stabilities were simultaneously achieved in the sample with x = 0.1. This work provides a feasible method for designing lead-free ceramics with high energy storage performances.

Automated summary

In this study, AgNb0.85Ta0.15O3 was successfully introduced to modify lead-free relaxor ferroelectric ceramics based on Na0.5Bi0.5TiO3, achieving the goal of enhancing breakdown electric field strength. The addition of AgNb0.85Ta0.15O3 resulted in ceramics with superior performance in terms of energy storage properties.