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

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.