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A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.

Organic phase change materials (PCMs) have exhibited many promising potentials for thermal energy conversion and storage, but they are still confronted with many technical bottlenecks for practical application, such as low conductivity, leakage during phase transition process, and lack of functionality. In this article, a highly-efficient electro/photo to heat conversion system of polyurethane@graphite foam (PU@GF) phase change composites was successfully fabricated through in situ polymerization of polyethylene glycol (PEG) in GF. The obtained PU presents solid–solid phase transition behavior that is different from the solid–liquid phase change of original PEG, which can prevent PU from leakage even if it was loaded in micrometer pores in the GF during application. On the other side, PU can improve the thermal stability and decrease the overcooling degree of the composites in effect. Excellent conductive network was provided by the GF, with which the light absorption and thermal conductivity of the composites were enhanced dramatically. Consequently, the solid–solid phase change composites can effectively store electricity or sunlight energy. The electro-heat storage efficiency of the composites can exceed 80% at 1.2 or 1.4 V, meanwhile, the photo-heat storage efficiency can close to 67% under simulated solar illumination. This result presents the highest efficiency for electro-to-heat conversion by PCMs techniques driven by a quite low voltage up to now, and will give rise to a new expectation of functional PCM application for energy conversion and storage.

Here we report catalyst-free combined synthesis of metal/semiconductor Zn/ZnO core/shell microspheres with hollow interiors on Si substrate and metallic Zn polygonal microparticles on glass substrate in a single experiment via thermal evaporation and condensation technique using nitrogen (N 2 ) as carrier agent at 800 °C for 120 min. The Zn/ZnO hollow microspheres were observed to have dimensions in the range of 70–80 μm whereas metallic Zn microparticles with polygonal cross section and oblate spherical shape were found to be of 8–10 μm. Some of the Zn/ZnO core/shell hollow spheres were also observed to have single crystalline ZnO pointed rods in extremely low density grown on the outer shell. The structural, compositional and morphological characterization of the products obtained on the substrates were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapor–liquid–solid (VLS) process based growth mechanism was proposed for the formation of Zn/ZnO core/shell microspheres with hollow interior. The optical properties of Zn/ZnO core/shell microspheres were investigated by measuring the photoluminescence (PL) spectra at room temperature (RT). Two very strong emission bands were observed at 373 and 469 nm in the ultraviolet and visible regions respectively under excitation wavelength of 325 nm. Also the effect of the various excitation wavelengths on the PL behaviour was studied at room temperature. PL studies of Zn/ZnO core/shell microspheres show the promise of the material for applications in UV and blue light optical devices.

Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

We have utilized the lattice mismatch between two adjacent nanocrystals in polycrystalline BFO ceramics to introduce a layer of highly strained BFO phase by taking advantage of crystal growth course. Therefore, a spin-valve like structure has been fabricated that consists of ferromagnetic phase (highly strained BFO phase)/antiferromagnetic phase (bulk BFO nanoparticles), without any substrates or alloy layers. BFO ceramics can present an exchange biasing effect ((|HEB|) ∼ 36 Oe) with an enhanced magnetic moment (Ms ∼ 0.11 μB Fe−1) and in addition saturated polarization (2Pr ∼ 57.4 μC cm−2) at room temperature. A low working electric field (Ec ∼ 4.8 kV cm−1) shows an advantage of low energy consumption in application. These results imply that there is potential for room temperature applications of single phase BFO with exchange biasing, enhanced magnetization and saturated polarization.

This paper reports on the non-traditional corrosion method for the synthesis of hematite mesocrystals in the size range of 30 μm. The results clearly show that the self-assembly of hematite mesocrystals were consisted of many small building units which were densely packed. The formation mechanism for hematite mesocrystals is proposed, which belongs to nonclassical crystallization. Ammonium chloride (NH4Cl), as a reagent in the reaction, has played a key role in the formation of hematite mesocrystals. The high coercivity of hematite mesocrystals of 4437.80 Oe was recorded. The origin of the large coercivity is also discussed. The size of the building units is the main reason, the anisotropies of the mesocrystals, defects, strain and exchange coupling are attributed to the enhancement of the large coercivity. All of the reasons for the explanation of the large coercivity can be attributed to the presence of N. The synthesis route is economical and environmentally friendly and is a promising way to fabricate other kinds of mesocrystals.