Enhanced recoverable energy storage density and breakdown strength in cation-site modified K0.5Bi0.5TiO3-based ergodic relaxor ferroelectric

Bi-containing ferroelectrics like Na0.5Bi0.5TiO3 (NBT) and K0.5Bi0.5TiO3 (KBT)-based materials are extensively investigated to achieve high recoverable energy storage density (Wrec) and efficiency (η). In this work, Bi-site modified KBT-based compositions have been studied for energy storage application at room temperature. KBT has been transformed from a non-ergodic to an ergodic relaxor state through the Eu3+ substitution. High breakdown voltage and slim polarization vs electric field loop are observed in 6 mol% Eu3+-substituted KBT, and high maximum polarization (Pmax) is retained along with low remnant polarization (Pr) in this composition. These features help to attain the Wrec and efficiency of 1.3 J/cm3 and 72%, respectively in 6 mol% Eu3+-substituted KBT at room temperature. This work demonstrates a strategy to enhance the Wrec and η by forming a stable ergodic relaxor state in the KBT-based material.