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and Technology. His research direction is electronic functional materials, including designing and exploiting piezoelectrics, ferroelectrics, and pyroelectrics. Ge Wang is currently working as a PDRA in functional materials and devices group at the University of Sheffield, UK. He obtained his Ph.D. from the University of Manchester in 2017 then moved to the University of Sheffield. His research interests include dielectric ceramic capacitors, piezoelectrics, solid oxide fuel cells, and Li batteries.

Single-phase homogeneous (Na0.2Bi0.2Ba0.2Sr0.2Ca0.2)TiO3 powder with high configurational entropy was synthesized by using a solid-state method. Calculations of thermodynamic parameters and related experiments indicate that both entropy and enthalpy drive the formation of a stable system. To further research the material's performance, we sintered the powder into a ceramic, which exhibited relaxation behavior because of the disorder of the microscopic composition. In addition, an applied electric field of 145 kV/cm produces a discharge energy density of 1.02 J/cm3. Meanwhile, the adiabatic temperature is 0.63 K at 60 kV/cm. These properties suggest that the electrocaloric effect of the (Na0.2Bi0.2Ba0.2Sr0.2Ca0.2)TiO3 ceramic is attractive for applications such as solid-state refrigeration and energy storage. High-entropy perovskite oxides are also highly tolerant to ions, and their properties can be tailored by tuning their composition, making them attractive for a broad range of applications.

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In this study, a high‐entropy perovskite oxide Sr(Zr0.2Sn0.2Hf0.2Ti0.2Nb0.2)O3 (SZSHTN) was first introduced to Na0.5Bi0.5TiO3 (NBT) lead‐free ferroelectric ceramics to boost both the high‐temperature dielectric stability and energy storage performance. Excellent comprehensive performance was simultaneously obtained in the 0.8NBT–0.2SZSHTN ceramic with high ε′ value (> 2000), wide ε′‐temperature stable range (TCC < 5%, 52.4–362°C), low tanδ value in a wide range (<0.01, 90–341°C) and high energy storage performance (Wrec = 3.52 J/cm3, Wrec and η varies ±6.08% and ±7.4% from 20 to 150°C), which endows it the promising potential to be used in high‐temperature environments.

Ba(FeTa)O/poly(vinylidene fluoride) (BFT/PVDF) flexible nanocomposite films are fabricated by tape casting using dopamine (DA)-modified BFT nanopowders and PVDF as a matrix polymer. After a surface modification of installing a DA layer with a thickness of 5 nm, the interfacial couple interaction between BFT and PVDF is enhanced, resulting in less hole defects at the interface. Then the dielectric constant (ε'), loss tangent (tan δ), and AC conductivity of nanocomposite films are reduced. Meanwhile, the value of the reduced dielectric constant (Δε') and the strength of interfacial polarization (k) are introduced to illustrate the effect of DA on the dielectric behavior of nanocomposite films. Δε' can be used to calculate the magnitude of interfacial polarization, and the strength of the dielectric constant contributed by the interface can be expressed as k. Most importantly, the energy-storage density and energy-storage efficiency of nanocomposite films with a small BFT@DA filler content of 1 vol % at a low electric field of 150 MV/m are enhanced by about 15% and 120%, respectively, after DA modification. The high energy-storage density of 1.81 J/cm is obtained in the sample. This value is much larger than the reported polymer-based nanocomposite films. In addition, the outstanding cycle and bending stability of the nanocomposite films make it a promising candidate for future flexible portable energy devices.

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