Realizing high low-electric-field energy storage performance in AgNbO3 ceramics by introducing relaxor behaviour

TLDR

Lead‑free dielectric capacitors with high energy density at low electric fields are needed for sustainable development and high‑power system safety. Improved anti‑ferroelectric stability from reduced tolerance factor and electronegativity difference, combined with Sr‑induced relaxor behavior from increased local disorder, underpins the performance. Ag₀.₉Sr₀.₀₅NbO₃ ceramics deliver 2.9 J cm⁻³ energy density and 56 % efficiency at 190 kV cm⁻¹, maintain <5 % energy density variation from 20–140 °C, and are promising low‑field capacitors.

Abstract

Both sustainable development in environment and safety of high-power systems require to develop a novel lead-free dielectric capacitor with high energy density (Wrec) at low applied electric field. In this work, a remarkably high Wrec of 2.9 J/cm3 accompanying with energy storage efficiency of 56% was achieved in Ag0.9Sr0.05NbO3 ceramic at a low applied electric field of 190 kV/cm, by improving anti-ferroelectricity and introducing relaxor behaviour. The improved anti-ferroelectric stability was attributed to the decreased tolerance factor and average electronegativity difference, while the relaxor behaviour was associated with the increased disordered local structure by Sr-doping. Moreover, the Ag0.9Sr0.05NbO3 ceramics also exhibited outstanding temperature stability in energy density with small variation less than 5% over 20–140 °C. The results indicate that the Ag0.9Sr0.05NbO3 ceramic is a promising candidate for low-electric-field driving capacitors.