Influence of Sr/Ba ratio on the energy storage properties and dielectric relaxation behaviors of strontium barium titanate ceramics

Sr _x Ba_1?x TiO₃ (x = 0.50–0.70) ceramics were prepared by conventional solid-state method. The effects of Sr/Ba ratio on the microstructures, energy storage properties and dielectric relaxation behaviors of ceramics were systematically investigated. Scanning electron microscopy observations revealed that the grain size was inhibited with increasing Sr molar fraction. The Sr_0.6Ba_0.4TiO₃ ceramics obtained the highest energy density of 0.3629 J/cm³ attributed to the increase of average breakdown strength resulting from the decrease of grain size and the optimizing of microstructure. In order to investigate the influence of Sr/Ba ratio on the dielectric relaxation behaviors, the activation energy has been calculated from the relaxation of dielectric loss and the complex impedance spectra by the Arrhenius relationship, respectively. The same results indicated that the decrease of grain size resulting in more grain boundaries, it was difficult for transferring charge and making an orientation under external electric field. Meanwhile, more defects existed at grain boundary and accelerated the thermally activated motions of defects, leading to the increase of activation energy.