Structure, dielectric and relaxor properties in lead-free ST-NBT ceramics for high energy storage applications

(1-x)SrTiO3-x(Na0.5Bi0.5)TiO3 ((1-x)ST-xNBT) ceramics have been prepared by solid-state route and their structure, electric and energy storage properties have been investigated. Dielectric anomalies at Tm and T′m show strong frequency dispersion as the typical relaxor ferroelectrics behavior over a broad temperature range. The Tm of (1-x)ST-xNBT ceramics dramatically shifted to a higher temperature (from −118 °C to 106 °C at 1 kHz) with increasing x. All samples showed the broad relaxor behavior due to the increase in the degree of lattice disorder and the thermal evolution of PNRs, and exhibited a discharge energy density of more than 1.18 J/cm3. The x = 0.4 sample exhibited a maximum discharge energy density of 1.70 J/cm3, consistent with the high value of Eb (∼21 kV/mm) and Pm (∼25 μC/cm2). The results indicate that (1-x)ST-xNBT ceramics might be a promising environmental friendly material for energy storage application.