Enhanced electrical properties of (Bi0.2Na0.2Ba0.2Ca0.2Sr0.2)TiO3 high-entropy ceramics prepared by hydrothermal method

In this study, (Bi0.2Na0.2Ba0.2Ca0.2Sr0.2)TiO3 (BNBCST) high-entropy ceramics (HECs) were prepared by using hydrothermal-synthesized powders. According to the characterizations of microstructure and crystal structure, the BNBCST HECs sintered at 1180–1220 °C exhibit a great chemical homogeneity and a single tetragonal phase. Compared to BNT, the chemical element disorder at A-site of BNBCST results in a large lattice distortion, which effectively disturbs the symmetry of the TiO6 octahedron and leads to dielectric relaxation as well as enhanced energy storage performance in HECs. The dielectric, ferroelectric and energy storage performances are density dependent. For the sample sintered at 1200 °C, a dielectric constant of 3788 and a recoverable energy storage density (under 127 kV/cm) of 1.37 J/cm3 can be achieved. This work shows that powder preparation by hydrothermal method is a promising approach to fabricate high-entropy ferroelectric ceramics and the prepared BNBCST is a practicable alternative for electrical energy storage applications.