Improved dielectric energy storage performance of BaO-Na₂O-Nb₂O₅ glass ceramics by various amount Dy³⁺ doping

Dielectric glass ceramics that combine high power density and high energy density have important application value in achieving lightweight, miniaturization, and integration of pulse power devices. Compared to dielectric ceramics and polymers, dielectric glass-ceramics are composites consisting of a ceramic phase dispersed within a glass phase. Through the processes of high-temperature melting, rapid cooling, and specific-temperature crystallization, the ceramic phase becomes uniformly distributed within the dense glass matrix. This results in a composite structure characterized by low porosity, uniform grain size, and high density. Owing to the introduction of the high-dielectric-constant ceramic phase, the glass-ceramics exhibit excellent dielectric response. Furthermore, the pore-free, continuous, and highly insulating glass matrix effectively enhances the overall breakdown resistance of the material. Different molar concentrations of rare earth Dy³⁺ doped BaO-Na₂O-Nb₂O₅ based glass ceramics were prepared using high-temperature melting combined with temperature-controlled crystallization process. Raw materials of glass ceramics were weighed according to the stoichiometric ratio and homogeneously mixed using a ball mill. The thoroughly mixed raw materials were placed in a high-temperature glass furnace and melted at 1550 ℃ for 2.5 hours to ensure complete fusion. The melt was then rapidly cast into a preheated metal mold to obtain bulk glasses. These glasses were annealed at 650 ℃ for 3 hours to relieve residual stresses. Subsequently, the transparent bulk glass blocks were cut into thin slices. Finally, these slices were heat-treated at 1100 ℃ for 3 hours. Upon cooling, Dy³⁺ doped BaO-Na₂O-Nb₂O₅-based glass-ceramics with varying molar concentrations of the rare-earth ion were obtained. The effects of different molar concentrations of rare earth Dy³⁺ doping on the microstructure, crystallization behavior, and dielectric energy storage performance of BaO-Na₂O-Nb₂O₅ based glass ceramics were systematically studied. The test results show that rare earth Dy³⁺ doping has almost no effect on the phase structure of BaO-Na₂O-Nb₂O₅ based glass ceramics. Moderate rare earth Dy³⁺ doping can effectively promote the precipitation of Ba₂NaNb₅O₁₅ ceramic phase in tungsten bronze structure, while improving the crystallinity of glass ceramics and increasing the dielectric constant of glass ceramics. In addition, rare earth Dy³⁺ doping also has the effect of inhibiting the growth of glass ceramic grains, which can improve the breakdown strength of BaO-Na₂O-Nb₂O₅ based glass ceramics. When the rare earth Dy³⁺ doping molar concentration is 4 mol%, the dielectric constant of BaO-Na₂O-Nb₂O₅ based glass ceramic is 97, the breakdown strength reaches 1485kV/cm, and the highest energy storage density reaches 8.01 J/cm³, which is 1.87 times that of undoped glass ceramics. This result provides experimental basis and technical reference for improving the performance of glass ceramic materials in the field of energy storage.