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

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 (Wrec) of 1.6 J cm-3 at 140 kV cm-1. In addition, the incorporation of MnO2 into AgNbO3 can further increase Wrec, 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 Wrec = 2.5-2.9 J cm-3 over a temperature range of 20-180 °C at 150 kV cm-1 and 1 Hz.