查看更多>>摘要：? 2022 Elsevier B.V.We have found that body-centered cubic (bcc) HfMoNbTiZr is a type-II BCS high-entropy alloy (HEA) superconductor with a superconducting critical temperature of Tc = 4.1 K. By employing a Debye temperature θD of 263 K and Tc, the electron-phonon coupling constant λe-p is calculated to be 0.63. The electronic structure calculation revealed band broadening with energy uncertainties due to atomic disorders. The superconducting properties are compared among equiatomic quinary bcc HEA superconductors. Tc decreases with decreasing λe-p, which is negatively correlated with θD. The negative correlation between λe-p and θD would be caused by a shorter phonon lifetime at a higher θD, which is based on phonon broadening due to atomic disorder and the uncertainty principle. The Vickers microhardness was measured for several bcc HEA superconductors. Tc is exceptionally low in a superconductor with relatively high hardness, because the hardness generally increases with increasing θD, and θD is negatively correlated with Tc in the high-entropy state.
查看更多>>摘要：? 2022 Elsevier B.V.Efficient cleanup of oil spills is still a global challenge due to the high viscosity of crude oil and complicated topographic features. Herein, magnetic porous carbon powders (MPCs) with photothermal effect prepared at a Fe(NO3)3: bamboo mass ratio was 1/1 carbonized at 700 °C. After modifying with the n-octadecylamine, the oleophilic MPCs exhibited rapid and selective absorption of different oils from polluted water, with an optimal absorption capacity of 3.2–8.1 g/g. Since oil's viscosity is highly temperature-sensitive, MPCs with photothermal characteristics offer apparent advantages in absorbing high viscosity oil. Moreover, due to the incorporation of magnetic components, powder-like MPCs can be conveyed to a specified oil pollution spot (including gaps or cracks) conveniently and collected through a remote magnetic field. This work demonstrates a simple and low-cost way of designing and producing oil/water separation materials, particularly floating high-viscosity oil recovery.
查看更多>>摘要：? 2022In this paper, the microwave dielectric properties of SrSm2O4 ceramics were reported, and the relationship between the phase composition, structure, density, microscopic morphology and properties is investigated. The SrSm2O4 ceramics have a good crystal structure corresponding to the standard card of PDF:032–1254. After sintered at the optimum temperature of 1400 ℃, the ceramic grains are closely connected, with clear grain boundaries and uniform grains are observed. The bulk density of SrSm2O4 ceramics sintered at 1400 ℃ for 4 h is 6.35 g/cm3 and the relative density reaches 91.63 %. Finally, the ceramics sintered at 1400 ℃ have the best performances of Q×f = 40646 GHz (at 8.64 GHz), εr = 18.16, τf = ?17.6 ppm/℃. The results show that SrSm2O4 has a good application prospect in 5 G/5 G+ field.
查看更多>>摘要：? 2022Owing to open-circuit voltage (VOC) deficits, Cu2ZnSn(S,Se)4 (CZTSSe) alloy film solar cells have limited improvements in device performance. Cation replacement in CZTSSe absorbers is key in studying the enormous potential of kesterite solar cells and thus in developing cost-effective photovoltaic technology. In this study, Cu2CrxZn1?xSn(S,Se)4 (0 ≤ x ≤ 0.2) (CCZTSSe) films were prepared using solution-processing and a two-step annealing technique. The device properties and effects of Cr-doping on the structure, morphology, and optoelectrical performance of the CCZTSSe films were investigated. The results showed that appropriate Cr-doping promotes grain growth, which enables the production of compact CCZTSSe films with larger grain sizes and fewer holes. In addition, the significantly enhanced absorption of the CCZTSSe thin films indicates the presence of intermediate bands (IB) in the band gaps, which promotes the absorption of low-energy photons. Cr-doping can also reduce the CuZn antisite defects. Finally, the efficiency of the CCZTSSe (x = 0.1) device was enhanced from 3.74 % to 5.44 %, and the VOC was boosted from 0.35 V to 0.39 V, compared to the pure CZTSSe (x = 0) device. These findings pave the way for improvements in the efficiency of CZTSSe devices.
查看更多>>摘要：? 2022 Elsevier B.V.Polycrystalline Zn1?xCrxTe samples for x = 0.00, 0.05, 0.10, 0.15, 0.18, and 0.20 were synthesized by solid-state reaction, and their physical properties were studied for the purpose of identifying a novel non-oxide transparent diluted magnetic semiconductor (DMS). Their transport properties exhibit semiconducting behavior for low Cr concentrations and become conductors for higher Cr concentration concentrations. Ferromagnetic behavior was observed in Cr-doped ZnTe with Curie temperature Tc increasing as Cr concentration increases. At x = 0.20 Cr concentration, the system has Tc above room temperature, indicating an interesting II-VI ferromagnetic semiconductor. Furthermore, optical transparency in the visible light range was found to be 30–85 % for different Cr concentration concentrations. Also, according to the electrical transport measurement data in this study, the resistivity doesn't exhibit any significant change as the temperature increases for x = 0.20. This consistent resistivity exhibits a possible candidacy for further studies of the sample Zn0.80Cr0.20Te for half-metallic ferromagnetic properties.
查看更多>>摘要：? 2022 Elsevier B.V.Different phases of copper sulfide were synthesized by the Flash Evaporation method, followed by annealing at various temperatures. Pure and mixed crystal structures of the covellite, digenite and djurleite phases were identified by the X-ray diffraction patterns and Raman spectroscopy. Scanning Electron Microscopy revealed the effect of annealing on the surface morphology. The carrier concentration was found to decrease with increasing the annealing temperature due to the disappearance of copper vacancies. This results in an increase in the Seebeck coefficient and a decrease in the electrical conductivity. The thermoelectric power factor is better when the digenite phase dominates and doping may be a possible solution towards the integration of this material in the thermoelectric technology. Finally, annealing provided access to the Density Of States engineering, which is useful for future investigations.
查看更多>>摘要：? 2022 Elsevier B.V.Tremendous effort has been put into radiative cooling for its great potential of alleviating energy consumption and greenhouse gas emission. However, there remains a big challenge to tackle the puzzle of combining the color display and radiative cooling with scalable and simplified membrane structure. Here, we report a novel monolayered hybrid membrane (MHM) using dielectric core-shell microsphere-embedded polydimethylsiloxane to achieve luminescence and radiative cooling bifunctionality. The dielectric shell constructed through the zinc ion diffusion upon the surface of spheric silica serves as both color display and infrared radiative improvement, while the core-shell structure provides high-efficient light scattering pathway, allowing enhancement of solar reflection. We show that the fabricated MHM exhibits a high solar reflectivity of 93 % and infrared emissivity over 0.96. Under typical outdoor environment with the solar intensity over 800 W m?2, such MHM can achieve a sub-ambient temperature drop of 7.8 °C with the mainstream method and 3.9 °C with the Stevenson screen one. More interestingly, the dielectric shell enables the MHM with a brilliant green coloration, potential UV resistance, and certain aesthetic purposes.
查看更多>>摘要：? 2022 Elsevier B.V.The microstructure evolution and deformation mechanism of a Ti-6Cr-5Mo-5 V-4Al (Ti-6554) alloy during high temperature compression is investigated based on the power dissipation efficiency (η). It is found that raising the temperature and decreasing the strain rate can promote the DRX process. Two types of DRX are found: discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX). Furthermore, combined with the change of η in the whole strain range and the peak η under different conditions, this study links η with the corresponding deformation mechanism of Ti-6554 alloy. It can be summarized as follows: the corresponding efficiency value of the DDRX process needs to exceed 0.45; the occurrence of CDRX requires that the η value is higher than 0.3. Dynamic recovery (DRV) becomes dominant when the η value is less than 0.3. Some typical instability phenomena appear when the η value is less than 0.2. This study can provide an effective means to determine the deformation mechanism of the Ti-6554 alloy.
查看更多>>摘要：? 2022 Elsevier B.V.Electrospun fibrous materials are promising electrolytic candidates suitable for all-solid-state lithium batteries (ASSLBs), owning to high ionic conductivity and energy density. However, the limited conductivity is yet to overcome and exploring chemistries for decorating them using electro-active filler of dopants is suggested by experts. In this direction, copper oxide (CuO), nickel oxide (NiO), and cobalt oxide (Co3O4) have also gained considerable attention due to their intriguing properties in various electrochemical devices. Herein, nano CuO, NiO, and Co3O4 were synthesized and used as the filler in the polyethylene oxide-based electrospun fibers to approach a proper electrochemical behavior. The obtained electrolytes were fully characterized using appropriate analytical systems. Based on the careful analysis of the results, incorporating 0.21 wt% nano CuO into the membrane led to approaching the most desirable characteristics by showing a higher concentration of free Li+ ions, greater amorphous domains, and lower Tg. Therefore, the highest ionic conductivity of 0.32 mS cm?1 was achieved at 25 °C. In addition, the CuO-filled fibers resulted in the activation energy drop from 53 to 19 kJ mol?1. The observed trends were confirmed through the estimation of dielectric and electrical properties. In a Li|LiCoO2 half-cell, reversible CV curves after 25 cycles as well as a stable structure up to 5.00 V were attained for the filled electrospun fibers. More significantly, the presence of CuO nanoparticles caused the discharge capacity increment from 68 to 120 mA h g?1 at 0.5 C for up to 100 cycles. Overall, the upgraded designing of the electrospun fibers through embedding the filler particles opens an influential way toward high-performance ASSLBs with appropriate safety.
查看更多>>摘要：? 2022 Elsevier B.V.Direct alcohol fuel cells (DAFCs) are renewable energy sources with the potential to replace fossil fuels. Investigating high-performance electrocatalysts that promote alcohol oxidation is critical. In this study, we demonstrate simple electrodeposition for the controlled synthesis of PdCo catalysts on Ni bowl-like micro/nano array films with the assistance of the monodisperse colloidal sphere template. The PdCo catalysts with the optimal properties was synthesized by optimizing the stirring rate of the electrolyte and the solution concentration. The Pd8Co1/Ni array film catalyst synthesized at a stirring speed of 200 Revolutions Per Minute (RPM) exhibited the highest electrochemical active surface area (ECSA, 95.65 cm2/mg) and specific and mass activities in methanol (173.2 mA/cm2 and 2032.9 mA/mgPd, respectively) and ethanol (240.1 mA/cm2 and 2846.1 mA/mgPd, respectively) oxidation in alkaline media. This was a considerable improvement compared to the electrocatalytic activities of single-phase Pd and a commercial Pd/C catalyst, and the superior performance of the Pd8Co1 micro/nano array film could be attributed to the bowl-like structure with a high ECSA and the synergistic effect of Pd and Co. Therefore, this study yields necessary insights into the development of high-performance electrocatalysts with potential applications in DAFCs.
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