Microstructural and dielectric characteristics of A-site high-entropy oxide ceramics with a perovskite structure

High entropy oxides with interesting physical properties can be obtained by the design of A-site cations. Herein, a series of medium entropy and high entropy perovskite ceramics (Ba0.25Sr0.25Ca0.25Bi0.25)TiO3, (Ba0.2Sr0.2Ca0.2Bi0.2La0.2)TiO3, (Ba0.2Sr0.2Ca0.2Bi0.2Na0.2)TiO3 and (Ba0.2Sr0.2Ca0.2La0.2Na0.2)TiO3 were synthesized by the solid-state method, which selected various valence elements to achieve a single-phase structure and increase the lattice distortion. The microstructure indicated that the high-entropy ceramics exhibited the same macroscopic single perovskite while the local configuration is different. Mesoscopic results show that high entropy can adjust the polarization and relaxation of ferroelectrics, so as to optimize the energy storage performance. Meanwhile, the results manifest that grain boundaries, oxygen defects and relaxation can be changed by entropy configuration. Our work proves that the properties of high entropy ferroelectric materials can be regulated by different valence states of the elements in high entropy and explores the relevant mechanism, which provides a possible opportunity for the design and application of high-entropy dielectric materials with excellent properties.