Crystallization Mechanisms and Energy-Storage Performances in BaO-SrO-Na2O-Nb2O5 Based Glass-Ceramics.

The [x BaO, (1 − x) SrO]-Na₂O (x = 0.0, 0.2, 0.5, 0.8) niobate-based glass-ceramics were prepared through the controlled crystallization method. Crystallization mechanism, phase structure, dielectric properties, and energy-storage properties were studied by adjusting Ba/Sr ratio. It was found that the surface and internal crystallization occurred simultaneously at first crystallization peak, while surface crystallization occurred at second crystallization peak. With Ba/Sr ratio increasing, dielectric constant increased firstly and then decreased, while dielectric loss firstly decreased and then increased. When x = 0.2, optimal dielectric constant of 88 and dielectric loss of 0.0055 were obtained, which is related to the solid solution phase Sr_0.5Ba_0.5Nb₂O₆. Breakdown strength (BDS) showed a behavior of increase before decrease. The highest BDS reaches 1975 kV/cm for x = 0.2, which is attributed to uniform and dense microstructure. Correspondingly, the theoretical energy-storage density was increased up to 15.4 J/cm³. Also, discharged efficiency reaches a high value of 91%. Discharged power density of 0.65 MV/cm³ was obtained for x = 0.2 in the RLC pulsed circuit. [ABSTRACT FROM AUTHOR]