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Graphene–copper (Gr–Cu) composite conductors have demonstrated Gr‐enhanced electrical and thermal properties. However, the conductors’ coupled mechanical and electrical responses remain unexplored despite the importance of their mechanical flexibility and robustness. Here, the electromechanical behavior of a recently developed microscale Gr‐Cu composite, called axially continuous graphene–copper (ACGC) wire, has been investigated by developing and utilizing a customized tensile testing method. Experimental studies have shown that 80 μm‐diameter ACGC (hereafter ACGC80) wires exhibit 3.681% and 3.173% higher compared to as‐received and annealed Cu wires, respectively. More importantly, the Gr‐enhanced electrical performance of the ACGC80 has been observed even after significant plastic deformation under uniaxial tension. To be specific, the conductivity of ACGC80 is 3.139%, 3.144%, and 3.088% higher than that of annealed copper wire at 3, 6, and 9% strain, respectively. Analysis indicates that ACGC80 deforms by forming highly localized plastic deformation zones along its length. This result suggests that graphene in ACGC80 serves as an effective electron pathway even after applying a large strain because the pronounced damage to graphene is limited to only a small fraction of ACGC80. The ACGC80 conductor has great potential to advance emerging applications in flexible interconnects, wearable electronics, and high‐power transmission for microchips. This study investigates the electromechanical behavior of 80 μm‐diameter axially continuous graphene–copper (ACGC80) wires by developing a customized tensile testing method. Experimental studies have shown that ACGC80 wires exhibit higher electrical conductivity compared to as‐received and annealed Cu wires, and more importantly, the Gr‐enhanced electrical performance of the ACGC80 has been observed even after significant plastic deformation under uniaxial tension.

Olivine-type LiFe1−xMnxPO4 (0 ≤ x < 1) is a high-energy cathode utilized in next-generation power sources. However, its poor electrical/ionic conductivity and Jahn–Teller distortions upon cycling limit its practical behaviors. To overcome these barriers, the use of monovalent Ag+ doping is confirmed to promote all key parameters (e.g., inherent electrical conductivity, cyclic lifespan, rate capability) of LiFe0.5Mn0.5PO4 cathodes. Theoretical calculations predict that this monovalent doping can narrow its bandgap, help shift the density of states toward a higher energy, and raise the electronic state numbers near the Fermi level, guaranteeing the high intrinsic electrical conductivity of the cathode. Four-probe testing solidly confirms that its conductivity can be vastly enhanced by 155.6% after Ag+ doping. In addition, we prove that 1% Ag+ doping is an optimal/economical choice to promote these electrochemical behaviors. Also, in situ x-ray diffraction detections further confirm that our doping can reinforce the lattice structures and inhibit lattice distortions. The assembled cells can output discharge capacity greater than 153.5 mAh g−1 at 0.1 C and achieve a capacity retention rate of 92.5% after 500 cycles, surpassing those of counterpart cases. Our work provides a smart two-birds-with-one-stone strategy to effectively elevate LiFe0.5Mn0.5PO4 cathodes for practical use.

We investigated the effects of molecular ordering on the electro-optical characteristics of organic light-emitting diodes (OLEDs) with an emission layer (EML) of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The EML was fabricated by a solution process which can make molecules ordered. The performance of the OLED devices with the molecular ordering method was compared to that obtained through fabrication by a conventional spin coating method. The turn-on voltage and the luminance of the conventional OLEDs were 5 V and 34.75 cd/m2, whereas those of the proposed OLEDs were 4.5 V and 120.3 cd/m2, respectively. The underlying mechanism of the higher efficiency with ordered molecules was observed by analyzing the properties of the EML layer using AFM, SE, XRD, and an LCR meter. We confirmed that the electrical properties of the organic thin film can be improved by controlling the molecular ordering of the EML, which plays an important role in the electrical characteristics of the OLED.

The mobility of pristine amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) is insufficient to meet the requirement of the future ultra-high-definition displays. Reported herein is the fabrication of hydrogenated long-channel IGZO TFTs exhibiting a transconductance and an on/off ratio that are orders of magnitude superior to those of the regular devices. The gate bias stability of the treated IGZO TFTs was greatly enhanced, with the threshold voltage shifting by less than 1 V after 1 h stress. Experimentally, the hydrogenation of the active layer was achieved via the deposition of a SiN x /SiO x bilayer on top of the IGZO via plasma-enhanced chemical vapor deposition followed by post-annealing under optimized conditions. The elemental depth profiles indicated that this enhanced performance originated from the hydrogen doping of the IGZO film. Furthermore, a dual-gate structure was fabricated to alleviate the deterioration of the subthreshold properties induced by the excess hydrogen doping.

Polyethylene glycol (PEG)-carbon nanotubes (CNTs) with expanded vermiculite (EVM) form-stable composite phase change materials (PCE-CPCMs) were constructed via the efficient synergistic effect between EVM and CNTs. The resultant material demonstrated simultaneously enhanced latent heat and heat transfer. The unique EVM pore structure and CNTs surfaces contributed to the form stability of PCE-CPCMs. The adsorption capacity was 77.75–81.54 wt %. The latent heat of the PCE-CPCMs increased with increasing CNTs content due to the decreasing inhibition effect of EVM and the increasing adsorption capacity of PEG, which was 83.9 J/g during melting and 104.2 J/g during solidification for PCE7.09. The pore confinement and surface EVM interactions inhibited the heat storage capacity of the PCE-CPCMs. Moreover, the inhibition effect on the heat storage capacity of PCE-CPCMs during the melting process was stronger than during solidification due to the crystallization-promoting effect. The heat transfer of PCE-CPCMs was significantly enhanced by the CNTs filler (0.5148 W/(m·K) for PCE7.09) due to the decrease in interfacial thermal resistance and the formation of rapid thermally conductive pathways. Fourier transform infrared spectroscopy, thermogravimetric analysis, and thermal cycles test results confirmed that the PCE-CPCMs exhibited excellent chemical compatibility, thermal stability, and reliability.

The effect of severe plastic deformation on the structure, strength, and electric conductivity of a Cu-Cr copper-based alloy has been studied. In ultrafine-grained specimens produced by severe plastic deformation by torsion and equal-channel angular pressing, the average grain size has been determined and particles of precipitates have been identified. The dependences of the strength and electric conductivity on conditions of severe plastic deformation and subsequent heat treatment have been assessed. The effect of dynamic aging in the Cu-Cr alloy has been found that leads to an increase in both the strength and the electric conductivity. It has been found that the ultrafine-grained alloy can demonstrate a combination of a high ultimate strength (790–845 MPa) and an increased electric conductivity (81–85% IACS).

Context Industrial production and humans cannot exist without energy, but the low efficiency of the heat transfer in the excessive use of energy is the most significant aspect of energy saving and emission reduction. Molecular dynamics simulation methods are devoted to simulate the heat transfer efficiency of a nanofluid system with different particle sizes, and the heat transfer enhancement mechanism of the nanofluid is simulated and studied from a microscopic perspective. The analysis showed that as nanoparticle size increases, the thermal conductivity of the Al–Ar nanofluid tends to decrease, but all of them are still higher than the thermal conductivity of the liquid argon system. According to the findings of the density and radial distribution function analyses, it can be seen that the microstructure of the system changes after putting solid nanoparticles to the original fluid. This alteration in the system’s microstructure is the primary component responsible for the increased heat transfer efficiency of nanofluids. Methods In this paper, based on the theory of molecular dynamics, the simulation calculations were mainly performed using LAMMPS software, which is a commonly used open source computational program in the field of MD simulation research. VMD is used for visualization and analysis. The Lennard–Jones potential function was used in the simulation to accurately describe the forces acting between the atoms.

Developing thermal storage materials is crucial for the efficient recovery of thermal energy. Salt-based phase-change materials have been widely studied. Despite their high thermal storage density and low cost, they still face issues such as low thermal conductivity and easy leaks. Therefore, a new type of NaCl-Al2O3@SiC@Al2O3 macrocapsule was developed to address these drawbacks, and it exhibited excellent rapid heat storage and release capabilities and was extremely stable, significantly reducing the risk of leakage at high temperatures for industrial waste heat recovery and in concentrated solar power systems above 800 °C. Thermal storage macrocapsules consisted of a double-layer encapsulation of silicon carbide and alumina and a self-standing core of NaCl-Al2O3. After enduring over 1000 h at a high temperature of 850 °C, the encapsulated phase-change material exhibited an extremely low weight loss rate of less than 5% compared with NaCl@Al2O3 and NaCl-Al2O3@Al2O3 macrocapsules, for which the weight loss rate was reduced by 25% and 10%, respectively, proving their excellent leakage prevention. The SiC powder layer, serving as an intermediate coating, further prevented leakage, while the use of Al2O3 ceramics for encapsulation enhanced the overall mechanical strength. It was innovatively discovered that the Al2O3 particles formed a network structure around the molten NaCl, playing an important role in maintaining the shape and preventing leakage of the composite thermal storage phase-change material. Furthermore, the addition of Al2O3 significantly enhanced the rapid heat storage and release rate of NaCl-Al2O3 compared to pure NaCl. This encapsulated phase-change material demonstrated outstanding durability and rapid heat storage and release performance, offering an innovative approach to the application of salt phase-change materials in the field of high temperature rapid heat storage and release and encapsulating NaCl as a high-temperature thermal storage material in a packed bed system. Compared with conventional salt-based phase-change materials, the developed product is expected to significantly improve the reliability and thermal efficiency of thermal storage systems.

The heat transfer surfaces of heat exchangers are usually made of metals which may suffer from severe corrosion. When corrosive fluids are present, highly corrosion-resistant metals, graphite or ceramics are used, resulting in high costs. This study presents measured data on the thermophysical and mechanical properties of recently developed corrosion-resistant polymer composite tubes for use in heat exchangers. Extruded polymer composite tubes based on polypropylene or polyphenylene sulfide filled with graphite flakes were investigated. The anisotropic thermal conductivities of the polymer composite tubes were measured at various temperatures. The through-wall thermal conductivity of the tubes made of polypropylene filled with 50 vol.% graphite is increased by a factor of 30 compared to pure polypropylene, resulting in a thermal conductivity of 6.5 W/(m K) at 25 °C. The tubes composed of polyphenylene sulfide filled with 50 vol.% graphite have a through-wall thermal conductivity of 4.5 W/(m K) at 25 °C. The mechanical properties of the polymer composites were measured using tensile and flexural tests at different temperatures. The composite materials are more rigid and keep their mechanical properties up to a higher temperature level compared to the unfilled polymers. Surface roughness measurements show the very smooth and sealed surface of the composite tubes. The results contribute to establishing the viability of using polymer composites for heat exchanger applications with corrosive fluids.

Coal fly ash (FA) valorization is of great significance and sustainable interests to addressing the current environmental challenges faced by coal power industry. Herein, this work attempted a novel molten salt Na2CO3 treatment for processing FA into a robust matrix to support lauric acid (LA) toward construction of latent phase change composite. Their micromorphology, physiochemical, and thermal properties were monitored with scanning and transmission microscopy, X-ray diffraction and FT-IR spectroscopy, differential scanning calorimetry, among others. As Na2CO3 dosage increased from 20% to 40%, the FA experienced firstly higher loss of SiO2 and then substantial loss of Al2O3, and yet exhibited merely varied porosity. Then, both the composites revealed a maximum LA content of 20% that doubled that of pristine FA. Nevertheless, the optimal composite was disclosed with thermal conductivity of 0.5668 W/mK, which was 69% higher than its FA-based counterpart. It was proposed that the surface roughness evidenced by the formation of tremendous grooves and gaps during thermal alkaline processing were accountable for the promoted carrying capacity toward organic component. Furthermore, the latent phase change composite revealed excellent durability, including negligibly varied phase transition temperature and enthalpy even after 1500 thermal cycling, which promised great interest in passive building cooling. Meanwhile, the finds here led to a new understanding into the structural origin of adsorption capacity by inorganic FA, and may provide guidance for better exploration of its characteristics for other applications.