Lead-free AgNbO3 anti-ferroelectric ceramics with an enhanced energy storage performance using MnO2 modification

Abstract

Dielectric ceramic materials have been actively studied for advanced pulsed power capacitor applications. Despite the good properties obtained in lead-based ceramics, lead-free counterparts are highly desired due to environmental regulations. This study revealed the potential of AgNbO₃ to be a promising lead-free ceramic for energy storage applications. AgNbO₃ ceramics fabricated using a conventional solid-state reaction method under an O₂ atmosphere show a characteristic anti-ferroelectric (AFE) double hysteresis loop at an electric field of >130 kV cm⁻¹, with a peak recoverable energy storage density (W_rec) of 1.6 J cm⁻³ at 140 kV cm⁻¹. In addition, the incorporation of MnO₂ into AgNbO₃ can further increase W_rec, exceeding 2.3 J cm⁻³ at 150 kV cm⁻¹ by the reduction of the remnant polarization, which is due to the enhanced AFE stability induced by the addition of MnO₂. Of particular importance is that the 0.1 wt% MnO₂-doped AgNbO₃ ceramics were found to possess a good thermal stability with W_rec = 2.5–2.9 J cm⁻³ over a temperature range of 20–180 °C at 150 kV cm⁻¹ and 1 Hz.