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Polycrystalline ceramics with the composition 0.45BaTi0.80Zr0.20O3-0.55Ba0.69Ca0.30Sm0.01Ti0.99Fe0.01O3 were prepared using the solid-state reaction route. The phase formation of the prepared sample was confirmed by x-ray diffraction (XRD) study. The temperature-dependent dielectric permittivity (ε) showed a diffuse phase transition. The observance of ferroelectricity at temperatures above the Curie temperature (TC) suggests the presence of nano-polar regions in the sample. The efficiency (ƞ), recoverable energy density (Wrec), and loss (Wloss) were determined from the P–E loops. The efficiency (ƞ) increased with an increase in temperature, while Wloss showed a reverse trend. The measured value of Wrec was 0.10 J/cm3, and a value of 94% was found for ƞ. The electrocaloric effect (ECE) was studied using the indirect method, and an adiabatic change in temperature (ΔT) of 0.34 K was found at 25 kV/cm with an electrocaloric coefficient = 0.0136 K cm kV−1. These results suggest that this composition can be used in energy storage and electrocaloric applications. [ABSTRACT FROM AUTHOR]

The effect of an electric field on thermal and dielectric properties as well as electrocaloric response in the ferroelectric NH 4 HSeO 4 has been studied using a universal multifunctional adiabatic calorimeter. The phase transition temperature between the ferroelectric and incommensurate phases is found to be highly sensitive to the electric field, d T 2 /d E ≈ 1.6 K/(kV/cm), at a low electric field strength. The intensive electrocaloric effect at E = 1.35 kV/cm observed by direct measurements, Δ T AD ≈ 0.045 K, as well as determined indirectly by analyzing the entropy-temperature-electric field phase diagram, Δ T AD ≈ 0.03 K, is quite large compared to the effects in other ferroelectrics. • Electric field effect on dielectric and thermal properties of NH 4 HSeO 4. • The highly sensitive to the electric field, d T 2 /d E , at a low electric field strength. • The maximum magnitude of the Δ S max ECE , at E = 3.0 kV/cm tends to the value of anomalous phase transition entropy Δ S 2 at T 2. • The magnitude of the intensive ECE is significantly larger than in related ferroelectrics NH 4 HSO 4 and (NH 4) 2 SO 4. • NH 4 HSeO 4 can be undoubtedly recommended we can undoubtedly recommend as a solid-state element for small cooling devices. [ABSTRACT FROM AUTHOR]