Excellent low electric field energy storage properties in Bi5Mg0.5Ti3.45Zr0.05O15 films via ion pair engineering

The Bi5Mg0.5Ti3.5−xZrxO15 (BMTZxO, x = 0.00, 0.05, 0.10, 0.15) ergodic relaxor ferroelectric films were prepared using a combined sol–gel and plasma technique. The polarization intensity of the films is enhanced by introducing multi-oriented B-site defect ion pairs and increasing local lattice distortion. The relaxor ferroelectric properties are improved by the interaction between defect ions pairs and weakly electronegative ions (Zr4+ and Mg2+ ions), which decouples domains and provides a restoring force for field-induced macrodomains. The BMTZxO (x = 0.05) film demonstrated superior energy storage performance under low-to-medium electric fields, achieving a recoverable energy storage density of 72.5 J/cm3 with an efficiency of 70.0%. This research offers a design approach for achieving superior energy storage performance in dielectric films.