Achieving high energy storage properties in perovskite oxide via high-entropy design

In recent years, “high-entropy” materials have attracted great attention in various fields due to their unique design concepts and crystal structures. The definition of high-entropy is also more diverse, gradually expanding from a single phase with an equal molar ratio to a multi-phase with a non-equimolar ratio. This study selected (Na0.2Bi0.2Ba0.2Sr0.2Ca0.2)TiO3 high entropy ceramics with excellent relaxation behavior. The A-site elements are divided into (x = Na, Bi, Ba) and ((1-3x)/2 = Sr, Ca) according to their inherent properties. A novel ABO3 structural energy storage ceramics (NaBaBi)x(SrCa)(1-3x)/2TiO3 (x = 0.19, 0.195, 0.2, 0.205 and 0.21) was successfully fabricated using the high entropy design concept. The ferroelectric and dielectric properties of non-equimolar ratio high-entropy ceramics were studied in detail. It was found that the dielectric constant of ∼4920 and the recoverable energy storage density of 3.86 J/cm3 (at 335 kV/cm) can be achieved simultaneously at x = 0.205. The results indicate that the design concept of high-entropy materials with a non-equal molar ratio is an effective means to achieve distinguished energy storage performance in lead-free ceramics.