Dielectric and energy storage properties of SrTiO3 modified Bi0.5Na0.5TiO3 ceramics

[Formula: see text] Bi[Formula: see text]Na[Formula: see text]TiO3-x SrTiO3 lead-free ceramics were prepared using the traditional solid-state method to investigate the influences of SrTiO3 content on the material’s phase structure, microstructure, dielectric and energy storageproperties. All the investigated compositions possess a stable perovskite structure with the coexistence of R phase T phase, and the proportion of the R phase in the samples decreases from 71.57% ([Formula: see text]) to 28.61% ([Formula: see text]) with the increase in ST content. The introduction of SrTiO3 leads to the dielectric anomalies at Ts and Tm, exhibiting strong frequency dispersion as the typical relaxor ferroelectrics behavior over a broad temperature range. The ferroelectric hysteresis curve indicates that the energy storage properties of the ceramics initially increased (reaching 0.7[Formula: see text]J/cm3 at 90[Formula: see text]KV/cm) and subsequently decreased with the rise in ST content. By analyzing the dielectric relaxation behavior of the samples using special oxygen treatment, XPS and PAT tests, we believe that the trend of changes in ceramic energy storage performance is caused by the competition between two types of PNRs formed by vacancy defects and Sr[Formula: see text] substituting for Bi[Formula: see text] and Na[Formula: see text]. In addition, the reasons for the formation of PNRs and their impact on dielectric relaxation performance are also discussed in detail.