An ultrahigh energy storage density up to 4.87 J cm ⁻³ was achieved in Sm/Ta co-doped AgNbO ₃ ceramics, by decreasing the cation displacement and [Nb/TaO ₆ ] octahedral tilting angle.

Ferroelectric/antiferroelectric thin/thick films with large positive or negative electrocaloric (EC) effects could be very useful in designing commercial refrigeration devices. Here, a giant negative EC effect (maximum ΔT ∼ −42.5 K with ΔS ∼ −29.3 J K⁻¹ kg⁻¹) comparable to the best positive EC effects reported so far is demonstrated for 0.5(Ba_0.8Ca_0.2)TiO₃–0.5Bi(Mg_0.5Ti_0.5)O₃ (BCT–BMT) lead-free relaxor ferroelectric thin films prepared on Pt(111)/TiO_x/SiO₂/Si substrates using a sol–gel method. An electric-field induced structural phase transition (nanoscale tetragonal and orthorhombic to rhombohedral) along the out-of-plane [111] direction plays a very key role in developing the giant negative EC effect. This breakthrough will pave the way for practical applications of next-generation refrigeration devices with high cooling efficiency in one cycle by ingeniously utilizing and combining both the giant negative and positive EC effects. Moreover, a large energy density of 51.7 J cm⁻³ with a high power density of 1.15 × 10¹⁰ W kg⁻¹ at room temperature is also achieved in the thin film, indicating that it is also an attractive multifunctional material for energy storage.

The Ba_(1−x)Ca_xZr_yTi_(1−y)O₃ (BCZT), a lead-free ceramic material, has attracted the scientific community since 2009 due to its large piezoelectric coefficient and resulting high dielectric permittivity. This perovskite material is a characteristic dielectric material for the pulsed power capacitors industry currently, which in turn leads to devices for effective storage and supply of electric energy. After this remarkable achievement in the area of lead-free piezoelectric ceramics, the researchers are exploring both the bulk as well as thin films of this perovskite material. It is observed that the thin film of this materials have outstandingly high power densities and high energy densities which is suitable for electrochemical supercapacitor applications. From a functional materials point of view this material has also gained attention in multiferroic composite material as the ferroelectric constituent of these composites and has provided extraordinary electric properties. This article presents a review on the relevant scientific advancements that have been made by using the BCZT materials for electric energy storage applications by optimizing its dielectric properties. The article starts with a BCZT introduction and discussion of the need of this material for high energy density capacitors, followed by different synthesis techniques and the effect on dielectric properties of doping different materials in BCZT. The advantages of thin film BCZT material over bulk counterparts are also discussed and its use as one of the constituents of mutiferroic composites is also presented. Finally, it summarizes the future prospects of this material followed by the conclusions.

KNN-based crystals with ultrahigh piezoelectric coefficients ( d ₃₃ = 1050 pC N ⁻¹ , and d ₃₃ * = 2290 pm V ⁻¹ ) were fabricated.