High-entropy design in (Ba_0.85Sr_0.15)TiO₃–Bi(Mg_2/3Ta_1/3)O₃ ceramics with temperature-stable dielectric performance

Ceramic capacitors with stable dielectric responses at elevated temperatures are of great importance for advanced electronic applications. In this study, high-entropy-engineered (Ba_0.85Sr_0.15)TiO₃–Bi(Mg_2/3Ta_1/3)O₃ solid solutions were developed to achieve broad-temperature dielectric stability. Among them, the composition with 25% and 30% Bi(Mg_2/3Ta_1/3)O₃ exhibit excellent dielectric properties, exhibiting room-temperature relative dielectric constants of 663 and 680, and dielectric losses of 0.6% and 1.1%, respectively. Particularly, they meet the X9R and X10R specification and dielectric loss of ∼0.6%, with capacitance variation less than ±15% from −74 °C to 265 °C, satisfying the X9R. The composition with 30% Bi(Mg_2/3Ta_1/3)O₃ shows the room-temperature dielectric constant of ∼680 and the dielectric loss of ∼1.1%, and showing TCC values within ±15% from −60 °C to 300 °C, which meets the X10R requirement. The improved dielectric temperature stability is associated with high-entropy-induced relaxor behavior together with enhanced high-temperature insulation characteristics, which jointly suppress dielectric loss and leakage current over a broad temperature range. These results demonstrate that high-entropy design is an effective route for developing high-performance temperature-stable dielectric materials for high-temperature capacitor applications.