Enhanced energy storage property in glass-added Ba(Zr _0.2 Ti _0.8 )O ₃ -0.15(Ba _0.7 Ca _0.3 )TiO ₃ ceramics and the charge relaxation

Glass additive BaO-SrO-TiO ₂ -Al ₂ O ₃ -SiO ₂ -BaF ₂ is employed to enhance the microstructures and energy storage properties of the Ba(Zr _0.2 Ti _0.8 )O ₃ -0.15(Ba _0.7 Ca _0.3 )TiO ₃ ceramics. To clarify the energy storage mechanism, the charge transportation and polarization process are investigated by thermally simulated depolarization current (TSDC). The dielectric breakdown strength increases from 4.3 kV/mm to 10.8 kV/mm for BZT-0.15BCT ceramics with 11 wt% glass additives, indicating that glasses could refine the grain size, uniform the structure, and decrease defects. Due to the micro-domain region, dielectric relaxation behavior is observed with a broadened and reduced dielectric constant peak at a large dielectric constant of about 3000 at room temperature. The largest charge energy density of 1.45 J/cm ³ and discharge density of 0.17 J/cm ³ are achieved for BZT-0.15BCT glass ceramics with 7 wt% glass additives. TSDC results demonstrate that dipole origin movement and charge transportation have an important effect on the dielectric properties and dielectric breakdown strength, respectively, which are largely influenced by the defects distribution state at the interfaces. Moderate domain walls could restrain the defects to inhibit the charge transportation and are harmful for the dielectric properties inversely. To achieve excellent energy storage performance, moderate domain walls are compromise of slightly degrading dielectric properties and greatly improving dielectric breakdown strength.