Lead-free BiFeO3-BaTiO3 based high-Tc ferroelectric ceramics: Antiferroelectric chemical modification leading to high energy storage performance
Hongliang Wang, Liang Shu, Liyu Wei, Xin Zhang, Qian Li, Jing‐Feng Li
Abstract
Dielectric capacitors have been widely used in pulsed power devices owing to their ultrahigh power density, fast charge/discharge speed, and excellent stability. However, developing lead-free dielectric materials with a combination of high recoverable energy storage density and efficiency remains a challenge. Herein, a high energy storage density of 7.04 J/cm3 as well as a high efficiency of 80.5% is realized in the antiferroelectric Ag(Nb0.85Ta0.15)O3-modified BiFeO3-BaTiO3 ferroelectric ceramic. This achievement is mainly attributed to the combined effect of a high saturation polarization (Pmax), increased breakdown field (Eb), and reduction of the remnant polarization (Pr). The modification of pseudotetragonal BiFeO3 by Ag(Nb0.85Ta0.15)O3 leads to a high Pmax, and the enhanced relaxor behavior gives rise to a small Pr. The promoted microstructure (such as a dense structure, fine grains, and compact grain boundaries) after modification results in a high breakdown strength. Furthermore, both the recoverable energy density and efficiency exhibit high stability over a broad range of operating frequencies (1–50 Hz) and working temperatures (25–120 °C). These results suggest that the (0.67–x)BiFeO3-0.33BaTiO3-xAg(Nb0.85Ta0.15)O3 ceramics can be highly competitive as a lead-free relaxor for energy storage applications.