Enhanced energy storage density of Ba0.4Sr0.6TiO3–MgO composite prepared by spark plasma sintering

(100 − x) wt%Ba0.4Sr0.6TiO3–xwt%MgO composite (x = 3, 5, 10) were prepared by spark plasma sintering (SPS) and their phase constitutions, microstructure and electrical energy storage properties were investigated. It was found that the reaction between Ba0.4Sr0.6TiO3 and MgO was suppressed due to low sintering temperature and short sintering period. The Curie temperature of BST/MgO composite is independent of the MgO content, which confirms the absence of chemical interdiffusion between BST and MgO. Diffuse phase transition was observed due to the reduced grain size and lack of sufficient chemical diffusion during SPS process. The dielectric breakdown strength of Ba0.4Sr0.6TiO3/MgO composite was greatly improved, which results in a significant improvement of maximum energy storage density. The high dielectric breakdown strength of 300 kV/cm, highest maximum energy storage density of 1.50 J/cm3 and high energy storage efficiency of 88.5% were obtained in 95 wt%Ba0.4Sr0.6TiO3–5 wt%MgO composite.