Improved energy-storage performance and breakdown enhancement mechanism of Mg-doped SrTiO_3 bulk ceramics for high energy density capacitor applications

摘要

We investigated the structure, dielectric properties and energy density performances of cubic perovskite-structured Mg-doped SrTiO_3 ceramics that were prepared by the solid-state reaction method. SrTiO_3 ceramic exhibited a relatively stable permittivity about 265-290 and enhanced dielectric breakdown strength (DBS) by Mg isovalent doping. Doping effects on the energy-storage properties in SrTiO_3 ceramics was performed by complex impedance analysis and polarization-electric field hysteresis loops. The energy storage density was dependent on DBS while energy efficiency was closely related to the remnant polarization. The possible physical mechanisms, including grain, gain boundary and interfacial polarization effects, were discussed to explain the improvement of dielectric breakdown strength. The bulk Mg-doped SrTiO_3 materials have shown interesting energy densities (1.86 J/cm~3) with good energy storage efficiency (about 89.3%) indicating that they can be a promising candidate for high energy density capacitor applications.