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Recent findings of a large electrocaloric (EC) effect in polymeric and inorganic ferroelectric materials open a potential possibility of development of solid-state cooling or heating devices of new generation with better energy efficiency that may be less harmful for the environment. We investigate by using direct measurements, the temperature and electric field dependence of the electrocaloric response in Pb1-xLax(ZryTi1-y)1-x/4O3 bulk ceramics (PLZT) with x = 0.06 and 0.12. Here, the properties of the EC response were probed in a part of the PLZT composition phase diagram with low y = 0.40 composition, in which the EC effect was not previously studied. Measurement results show the existence of the sizeable EC response in the 12/40/60 PLZT sample with the EC temperature change (ΔTEC) of 2.92 K at 430 K and 80 kV/cm. This value exceeds previously obtained ΔTEC values in relaxor ferroelectric x/65/35 PLZT compositions, rivaling the best EC response in lead magnesium niobate-lead titanate ceramics. The electrocaloric responsivity (ΔT/ΔE) value of 0.41 × 10−6 Km/V determined at a lower electric field of 20 kV/cm and 410 K is comparable to those observed in other perovskite ferroelectrics. [ABSTRACT FROM AUTHOR]

Direct and indirect electrocaloric measurements were performed on the new Tellurium (Te) doped Ba0.8Ca0.2TiO3 (BCT) ceramics. The effects of Te addition on structural, electrical, and electrocaloric properties of BCT ceramics were investigated. The incorporation of the Te element in the BCT induced the decrease of the Curie temperature and the enhancement of the electrocaloric effect. The significant electrocaloric temperature change DT = 1.237 K determined by the direct method was obtained at the relatively moderate field of ~25 kV/cm in Ba0.8Ca0.2Ti(1-x)TexO3 with x = 0.02. The corresponding electrocaloric responsivity DT/DE = 0.495 × 10-6Km V-1 is higher than that observed in pure BCT ceramics and is one of the highest reported so far in lead-free ferroelectric materials. The material's coefficient of performance was determined at the phase transition with a maximal value of 14.7. [ABSTRACT FROM AUTHOR]

High-performance lead-free multiferroic composites are desired to replace the lead-based ceramics in multifunctional device applications. Laminated compounds were prepared from ferroelectric and ferromagnetic materials. In this work, we present the laminated ceramics compound by considering the ferromagnetic La0.5Ca0.5MnO3 (LCMO) and the ferroelectric BaTi0.8Sn0.2O3 (BTSO) in two different proportions. Compounds ($1-x$) LCMO–($x$) BTSO with $x = 1$ and 0 (pure materials) were synthesized by the sol–gel method, and $x = 0.7$ and 0.5 (laminated) compounds were elaborated by welding appropriate mass ratios of each pure material by using the silver paste technique. Structural, dielectric, ferroelectric, microstructure, and magnetic characterizations were conducted on these samples. X-ray scattering results showed pure perovskite phases confirming the successful formation of both LCMO and BTSO. Scanning electron microscope (SEM) images evidenced the laminated structure and good quality of the interfaces. The laminated composite materials have demonstrated a multiferroic behavior characterized by the ferroelectric and the ferromagnetic hysteresis loops. Furthermore, the enhancement of the dielectric constant in the laminated composite samples is mainly attributed to the Maxwell–Wagner polarization. [ABSTRACT FROM AUTHOR]

Over the past decades, there has been significant interest in new cooling technology based on the large electrocaloric effect observed in polymeric and inorganic ferroelectric materials. We report a dramatic impact of annealing on the electrocaloric effect observed by direct measurements in Pb 0.88 La 0.12 (Zr 0.65 Ti 0.35) 0.97 O 3 bulk ceramics (12/65/35 PLZT). In addition, the EC response was measured deep in a relaxor part of the PLZT composition phase diagram. After additional one-hour sample annealing at 600 °C, the EC response increased by about six times. Electrocaloric results confirm the existence of the significant electrocaloric response with the EC temperature change (Δ T EC) of 4.5 K at 360 K and 90 kV/cm in an annealed sample. This value exceeds previously obtained maximum Δ T EC values at the same field in perovskite relaxor ferroelectrics such as Pb(Mg1/3Nb2/3)O 3 -PbTiO 3 (PMN-PT) and 8/65/35 PLZT ceramics. The electrocaloric responsivity Δ T /Δ E = 5.09 × 10−7 Km/V determined at 360 K is among the highest observed in bulk perovskite ferroelectrics at a relatively high electric field of 90 kV/cm. • Relaxor ferroelectrics exhibit mostly an electrocaloric effect (ECE) of about 3 K. • The stress field makes the ferroelectric state more supercritical with smaller ECE. • The annealing enhances the ECE in 12/65/35 PLZT ceramics by about six times. • ECE of 4.5 K exceeds previously obtained values in bulk relaxor ferroelectrics. • The ECE responsivity is the highest observed at a relatively high electric field. [ABSTRACT FROM AUTHOR]