查看更多>>摘要：? 2022Self-powered sensors have great application prospects in the field of analytic chemistry because they can determine analytes without inputting external electricity. In this work, Fe2O3 electrode with nanorod morphology was synthesized by chemical bath method, then a layer of Ni(OH)2 was decorated on the surface of Fe2O3 nanorods via successive ion adsorption. Furthermore, a Ni(OH)2/Fe2O3-based photo fuel cell (PFC) was fabricated as a novel self-powered sensor. The produced maximum power density (Pmax) of the sensor shows a linear relationship with glucose concentrations in the range of 0.05–0.25 mM with a sensitivity of 24.59 μW cm–2 mM–1, which is much higher than that of bare Fe2O3-based self-powered sensor (only 3.53 μW cm–2 mM–1). The better performance achieved on the Ni(OH)2/Fe2O3-based sensor is because Ni(OH)2 has high electrocatalytic activity for glucose oxidation and it can improve photo-generated charge inject efficiency (ηinj) to substrate. In addition, the sensor also possesses good selectivity, stability and applicability for glucose sensing. In a word, this work provides a non-enzymatic, simple-construction, cost-effective and sustainable PFC based self-powered sensor, which may guide future designs for the determination of analytes and offer a new route for utilization of widespread solar energy.
查看更多>>摘要：? 2022In this study, a multi-component single-phase CoNiCr-based MP159 alloy with a high dislocation density is investigated when subjected to cold rolling. The alloy has an ultra-high yield strength of 1807 MPa and large ductility of more than 20% at 77 K, with a significant temperature dependence. The difference in mechanical properties between cryogenic and room temperatures is illustrated by the analysis of the deformation structures, and the deformation twinning is found to make an critical contribution to high strength and large ductility. It provides an alternative way to strengthening metallic materials in the current investigation.
查看更多>>摘要：? 2022For the development of nuclear energy, it is important to remove the fission products which hinder nuclear reactions. In this paper, Gd was extracted by an electrochemical method in LiCl-KCl molten salts. The electrochemical reactions of GdCl3 and SnCl2 are measured by a series of electrochemical means. Three kinds of Sn-Li and four Sn-Gd alloys are obtained by cyclic voltammetry and other electrochemical means. Thermodynamic and kinetic parameters of electrode processes for Gd(III) and Sn(II) ions are calculated by different electrochemical test methods. The diffusion coefficient and diffusion activation energy of the Sn(II) ion are reactions as 2.23–3.78 × 10-5 cm2 s-1 and 24.4 kJ mol-1, respectively. Thermodynamic parameters of Sn3Gd intermetallic compounds were calculated based on open circuit chronopotentiometry at different temperatures (ΔHf0(Sn3Gd)=?229.225kJmol-1 and ΔSf0(Sn3Gd)=?38.2Jmol-1K-1). Metallic Gd is extracted by potentiostatic and galvanostatic electrolysis on liquid Sn electrode in melts, respectively. According to X-ray diffraction (XRD) and scanning electron microscopy and elemental dispersive spectrometry (SEM-EDS), the products are mainly composed of the intermetallic compound Sn3Gd and Sn metal. The experimental results show that the fission element Gd can be extracted with high extraction rate by electrolysis in molten salt system.
查看更多>>摘要：? 2022Lead-free BaZr0.25Ti0.75O3 films were grown on Pt/Ti/SiO2/Si substrates via a sol-gel method. The effects of different annealing temperatures (650–750 °C) on microstructure, dielectric and energy storage performances were systematically investigated. It was found that grain size, degree of crystallization and surface roughness of the films increased with the increasing temperature. Moderate polarization and high breakdown strength could be obtained in the film annealed at 700 °C, which not only achieved the optimal energy storage density of 60.8 J/cm3, but also exhibited good temperature stability in energy storage ranging from 20 °C to 200 °C. These results showed that BaZr0.25Ti0.75O3 films were expected to become a candidate material for lead-free energy storage capacitors.
查看更多>>摘要：? 2022 Elsevier B.V.Mg-based alloy anodes suffer from severe corrosion in conventional electrolytes (KOH solution) and this substantially obstructs the cycle life, which is a great challenge for using them in the Ni-MH battery. Herein, a high concentration tetramethylammonium hydroxide (TMAH) aqueous electrolyte with a special hydrate structure is explored and enables excellent cycle stability and high capacity for Mg-based alloy anodes. In this electrolyte, the Mg0.4Ti0.1Ni0.5 alloy anode delivers a maximum discharge capacity of 466 mAh g?1, and maintains 210 mAh g?1 after 100 cycles owing to the reduced corrosion rate, which are much better than that in 6 M KOH electrolyte, being 425 mAh g?1 and 69 mAh g?1, respectively. Furthermore, by in-situ forming Cu coating on the Mg0.4Ti0.1Ni0.5 electrode surface during charging process with the adding 0.01 M of Cu(OH)2 in TMAH electrolyte, the corrosion of the electrode is further suppressed and the reversible capacity can reach 313 mAh g?1 after 100 cycles. The high conducting Cu coating can also increase the rate capability of the electrode by promoting the charge transfer. Thus, using TMAH electrolytes provides a new approach to promote the electrochemical performances of Ni-MH batteries with Mg-based alloy anodes.
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, the microstructure, micro zone performance and compressive properties of FeCoNi1.5CuB0.5Y0.2 high-entropy alloys under different cryogenic treatment parameters (cryogenic temperature T, holding time t and cooling rate V) are studied. The results show that there are significant lattice distortions and changes in the morphology and size of each phase under different cryogenic conditions. In the optimized sample with cryogenic treatment conditions of T = ?196 ℃, t = 36 h and V= 5 ℃/min, the number of HCP phase and M3B phase increases significantly, the size is significantly reduced and a large number of nanoparticles appear. In terms of the mechanical properties of the micro zone, the nano-hardness and elastic modulus of each phase have been significantly improved compared with the untreated sample. For the optimized sample, the nano-hardness, compressive strength and fracture toughness also reach the maximum, which are 34.4%, 44.6% and 145% higher than that of the untreated sample respectively. It is analyzed that the cryogenic treatment of HEA results in dislocation strengthening, fine-grain strengthening, nano-heterogeneous particle strengthening, which promote the simultaneous improvement of the overall strength-ductility of the HEA.
查看更多>>摘要：? 2022 Elsevier B.V.We report synthesis of Carbon nanofibers (CNFs) and hybrid nanocomposites namely, CNF-Sn and C-Sn microspheres using simple electrospinning technique, followed by annealing in controlled atmosphere. The as-prepared materials were characterized using X-raydiffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Ultra-violet photoelectron spectroscopy (UPS), and Raman spectroscopy to reveal their physico-chemical properties. As carbon family members are potential materials for field emission (FE) based applications, owing to their high aspect ratio FE characteristics of the synthesized materials were explored at base pressure of 1 × 10?8 mbar. Interestingly, the hybrid nanocomposite CNF-Sn and C-Sn emitters showed improved FE behavior (with the turn-on field of 3.4 and 1.36 V/μm, respectively) in contrast to the pristine CNFs emitter (turn-on field of 5.4 V/μm). Furthermore, the maximum emission current density is substantially enhanced, 7.75 and 4.6 mA/cm2 for CNF-Sn and C-Sn emitters, respectively. The improvement in the FE behavior of nanocomposite emitters is attributed to the combined effect of morphology and modulation of electronic properties at the interface of nanocomposites. The results confirm that FE characteristics of pristine nanostructures can be greatly improved upon formation of their nanocomposites and this approach can be extended to other nanostructures for improving their multi-functionalities.
查看更多>>摘要：? 2022 Elsevier B.V.The deformed mixed grains of the initial aged GH4169 superalloy need to be refined by annealing treatment. However, for the isothermal annealing treatment, the deformed mixed grains can only be refined to about 10 μm because the increase of nucleation rate needs to increase the temperature while the decrease of grain growth rate requires to decrease temperature. In the paper, an innovative method including an aging treatment and a subsequent continuous-cooling recrystallization annealing treatment (CC-RAT) is proposed. This method can not only increase the nucleation rate but decrease the grain growth rate. The effects of heat treatment parameters on microstructure are investigated. Besides, the grain refinement mechanism is studied using a developed cellular automaton (CA) model. The results show that the recrystallization takes place slowly during aging, while large number of δ precipitates appear. In subsequent CC-RAT, increasing starting temperature (Ts), decreasing cooling rate (V) or ending temperature (Te) can remarkably promote recrystallization, thereby refining grain microstructure. This attributes to the increase of recrystallization nucleation rate and the effective control of grain growth rate. In the early stage of CC-RAT, δ precipitates hinder the quick growth of recrystallized grains nucleated firstly. Moreover, the increase of Ts accelerates the nucleation rate, and the decrease of V prolongs the time for nucleation. Both of them promote the rapid formation of new recrystallized nuclei, especially at δ phase boundaries. As the annealing temperature decreases, newborn grains grow slowly, and these new grains restrict the growth of grains nucleated first. Therefore, a fine and uniform microstructure with an average grain size of 5.82 μm is obtained. However, when Ts is too high or V is too low, some coarse recrystallized grains appear. Hence, the feasible process is concluded as follows: aging treatment (900 °C×12 h), followed by CC-RAT (Ts = 990–1010 °C, V=1–2 °C/min, Te=950–970 °C).
查看更多>>摘要：? 2022 Elsevier B.V.We have employed Gd55Co30NixAl15?x (x = 10, 5 and 0) amorphous microwires as a model system to unravel the impact of multiple magnetic interactions on the magnetism and the magnetocaloric behavior in Gd-alloy microwire systems. Our study shows that in addition to the RKKY ferromagnetic (FM) interaction (Gd-Gd), antiferromagnetic (AFM) interactions (Gd-Co, Gd-Ni) coexist and contribute to the magnetic and magnetocaloric response of the system. The dilution effect of Al element on the FM Gd-Gd interaction is responsible for the decrease of the Curie temperature (TC), whereas the increase of the saturation magnetization (MS) is originated from the reduced AFM Gd-Ni interaction. A thorough analysis of critical exponents suggests that the presence of the AFM interactions hinders the system to exhibit a long-range FM order below the TC. Adjusting these interactions is shown to preserve the large refrigerant capacity (RC) while tuning the TC over a wide temperature range, which is desirable for active magnetic refrigeration.
查看更多>>摘要：? 2022 Elsevier B.V.Four equiatomic five-component rare earth monosilicates solid solutions were prepared by spark plasma sintering. Two compositions with larger deviation of ionic radii, (Dy0.2Ho0.2Er0.2Tm0.2Yb0.2)2SiO5 and (Dy0.2Ho0.2Er0.2Y0.2Lu0.2)2SiO5, exhibit single-phase structures and homogenous elemental distributions. Extremely low high-temperature thermal conductivities below 1 Wm?1 K?1 and similar coefficients of thermal expansion with SiC were achieved for both compositions. Further, they both displayed good high-temperature stability and high corrosion resistance in water vapor. When exposed to 1400 °C, 90%RH water vapor, only slight weight losses were observed for both compositions during the initial half hours, after which almost no further weight losses were observed.
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