Preparation and dielectric properties of BaCu(B2O5)-doped SrTiO3-based ceramics for energy storage

BaCu(B2O5) (BCB) was used as sintering aids to lower the sintering temperature of multi-ions doped SrTiO3 ceramics effectively from 1300 °C to 1075 °C by conventional solid state method. The effect of BCB content on crystalline structures, microstructures and properties of the ceramics was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and dielectric measurements, respectively. The addition of BCB enhanced the breakdown strength (BDS) while did not sacrifice the dielectric constant. The enhancement of BDS should be due to the modification of microstructures, i.e., smaller and more homogeneous grain sizes after BCB addition. The dielectric constant of BCB-doped ceramics maintained a stable value with 1.0 mol% BCB, which was dominated by the combination of two opposite effects caused by the presence of second phases and the incorporation of Cu2+ and Ba2+, while further increase was owing to the increase of dissolved Ba2+ ions when the content of BCB is more than 2.0 mol%. The multi-ions doped SrTiO3 ceramics with 1.0 mol% BCB addition showed optimal dielectric properties as follows: dielectric constant of 311.37, average breakdown strength of 28.78 kV/mm, discharged energy density of 1.05 J/cm3 and energy efficiency of 98.83%.