LAUSR

Ba0.95Ca0.05ZrxTi1−xO3 (x = 0.20, 0.25, 0.30) ceramics were prepared by a citrate method. The microstructure, crystal structure and energy storage properties were investigated. Moreover, the dielectric properties of these specimens were examined as a function of temperature, frequency and electric field. The dielectric constant of Ba0.95Ca0.05ZrxTi1−xO3 ceramics was determined to be 4446, 3541 and 2224 for x = 0.20, x = 0.25 and x = 0.30, respectively, under zero electric field and room temperature. The dielectric loss was detected to be 0.9%, 0.8% and 0.3%, respectively, under the same condition. However, these samples displayed nearly identical energy storage densities at a given high-electric field, such as 0.41, 0.36 and 0.40 J/cm3, respectively, under 120 kV/cm, which can be explained by means of intrinsic lattice phonon polarization. The energy storage efficiency manifested a complicated variation, relying on polar nano-regions (PNRs) and dipole polarization at weak electric field and highly dependent on leakage conduction under strong electric field. Complex impedance spectroscopy analysis demonstrated that the mobile charge carriers in the specimens were oxygen vacancies, arising from lattice oxygen release during sintering. This work emphasized an important effect of oxygen-ion motion on the energy storage efficiency.