Structure and energy storage performance of Ba-modified AgNbO3 lead-free antiferroelectric ceramics

The AgNbO3 antiferroelectric (AFE) ceramics have attracted increasing attention for their high energy storage performance and environmentally friendly characters. In this work, Ag1–2xBaxNbO3 ceramics were successfully prepared by the conventional solid-state reaction method. The effect of Ba-modification on phase structure, microstructure, and electric properties was systematically investigated. The introduction of Ba2+ ion led to complex cell parameter evolution and significant refinement of grain size. Room temperature dielectric permittivity increased obviously from ~260 for the pure AgNbO3 counterpart to ~350 for those after adding a small amount of Ba element. Slim P-E hysteresis loops with improved AFE phase were achieved after Ba modification, due to the decrease of tolerance factor. A high recoverable energy density up to 2.3 J/cm3 with energy efficiency of 46% can be obtained for the composition of Ag0.96Ba0.02NbO3, in correlation with the enhanced AFE stability, reduced Pr, increased Pm and decreased ΔE. Moreover, the Ag0.96Ba0.02NbO3 ceramics also exhibited excellent temperature stability in both energy density and efficiency with small variation of < 5% over 20–120 ℃. The results suggest that the electric properties of AgNbO3 system can be largely tuned after Ba modification, making it a promising candidate for energy storage applications.