Pyrochlore-based high-entropy ceramics for capacitive energy storage

Abstract

High-performance dielectrics are widely used in high-power systems, electric vehicles, and aerospace, as key materials for capacitor devices. Such application scenarios under these extreme conditions require ultra-high stability and reliability of the dielectrics. Herein, a novel pyrochlore component with high-entropy design of Bi1.5Zn0.75Mg0.25Nb0.75Ta0.75O7 (BZMNT) bulk endows an excellent energy storage performance of Wrec ≈ 2.72 J/cm3 together with an ultra-high energy efficiency of 91% at a significant enhanced electric field Eb of 650 kV/cm. Meanwhile, the temperature coefficient (TCC) of BZMNT (∼ −220 ppm/°C) is also found to be greatly improved compared with that of the pure Bi1.5ZnNb1.5O7 (BZN) (∼ −300 ppm/°C), demonstrating its potential application in temperature-reliable conditions. The high-entropy design results in lattice distortion that contributes to the polarization, while the retardation effect results in a reduction of grain size to submicron scale which enhances the Eb. The high-entropy design provides a new strategy for improving the high energy storage performance of ceramic materials. [Figure not available: see fulltext.]