Solid-state cooling technology based on electrocaloric effect (ECE) has been advanced as an alternative to replace the vapour-compression approach to overcome the releasing of the global warming gases. However, the development in high ECE materials is still a challenge. In this work, polarization merging strategy was proposed to achieve a large ECE in xBa(Sn_0.07Ti_0.93)O₃–(1−x)Ba(Hf_0.1Ti_0.9)O₃ ferroelectric ceramics, where x = 0, 0.2, 0.4, 0.6, 0.8, and 1. Ba(Sn_0.07Ti_0.93)O₃ with an orthorhombic phase and Ba(Hf_0.1Ti_0.9)O₃ with a rhombohedral phase at room temperature were prepared beforehand as precursors, and phase-coexisted xBSnT–(1−x)BHfT ceramics were formed via a solid-state reaction approach. Phase coexisting structures were confirmed using the X-ray diffraction. The merged polarization was confirmed by the dielectric and ferroelectric properties. Optimal ECEs were obtained for 0.2BSnT–0.8BHfT ceramics, i.e., adiabatic temperature change ΔT = 2.16±0.08 K at 80 ℃ and 5 MV/m, and ΔT = 3.35±0.09 K at 80 ℃ and 7 MV/m.

Intra porous fibrous membranes have enhanced metal ionic adsorption and oil separation abilities than those of intra nonporous fibrous membrane. In this paper, we prepared highly intra porous fibrous poly (vinylidene fluoride) (PVDF) membranes using an innovated water-mediated electrospinning approach. FTIR-ATR and XRD techniques confirmed the conversion of non-polar α-phase to polar β-phase in electrospun membranes. The porous fibrous membrane M–16 had adsorbed oil almost 120% and metal adsorption around 15%, 12%, 5%, 13% respectively for Pb²⁺, Cd²⁺, Cu²⁺ and Zn²⁺, which are larger than the counterpart of nonporous M–18. The nonporous fibrous membranes have better peak to peak output voltage (V_p-V_p) 2 to 3 times than the porous fibrous membranes (M–16). The results show apparent potential applications in wastewater/oil spill treatment as well as piezoelectric sensors.

(Ba_1−xSr_x)(Mn_yTi_1−y)O₃ (BSMT) ceramics with x = 35, 40 mol% and y = 0, 0.1, 0.2, 0.3, 0.4, 0.5 mol% were prepared using a conventional solid-state reaction approach. The dielectric and ferroelectric properties were characterized using impedance analysis and polarization–electric field (P–E) hysteresis loop measurements, respectively. The adiabatic temperature drop was directly measured using a thermocouple when the applied electric field was removed. The results indicate that high permittivity and low dielectric losses were obtained by doping 0.1–0.4 mol% of manganese ions in (BaSr)TiO₃ (BST) specimens. A maximum electrocaloric effect (ECE) of 2.75 K in temperature change with electrocaloric strength of 0.55 K·(MV/m)^–1 was directly obtained at ~21 ℃ and 50 kV/cm in Ba_0.6Sr_0.4Mn_0.001Ti_0.999O₃ sample, offering a promising ECE material for practical refrigeration devices working at room temperature.