Phase Transitions in Bi/Ca Modified AgNbO <sub>3</sub> Ceramics with Excellent Energy Storage Density and Storage Intensity
Zhongna Yan, Jia He, Haiyan Chen, Dou Zhang, Yuan Liu, Hang Luo, Chuanchang Li, Isaac Abrahams, Haixue Yan
Abstract
Abstract Lead‐free antiferroelectric (AFE) ceramics based on AgNbO 3 represent attractive materials for energy storage applications but are limited by their recoverable energy density ( W rec ). Here Bi 3+ /Ca 2+ A‐site modification of AgNbO 3 ceramics has yielded a particularly high W rec of 4.4 J cm −3 and a superhigh recoverable energy storage intensity ( ρ ) of 21.46 × 10 −3 J kV −1 cm −2 at 205 kV cm −1 , the latter being the highest known value obtained at such a relatively low field for a lead‐free ceramic. The modification shifts the dipole freezing temperature, T f , to below room temperature, enhancing the room temperature stability of the AFE structure. The high W rec is attributed to the enhancement of the maximum field‐induced dielectric displacement and improved forward ( E F ) and backward ( E B ) fields. The work has also allowed for an examination of the poorly understood ± E U current peaks evident in current–electric field loops of AgNbO 3 ‐based ceramics, which is proposed to be related to a field‐induced AFE to ferroelectric (FE) phase transition in the M 1 or M 2a phases and is absent in the M 2b phase due to increased stability of the AFE phase. The exceptional performance of Bi 3+ /Ca 2+ modified AgNbO 3 ceramics is promising for potential use in ceramic capacitors for high pulsed power applications.