查看更多>>摘要：? 2022Mechanical performances have a strong correlation with processing technology for Al0.3CoCrFeNiMn high-entropy alloy. Thus, the current study adopts solution treatment, cold rolling and annealing to investigate their corresponding microstructure and mechanical properties, and the models of backpropagation artificial neural network are established by using collected data set. The results indicate that twinning induced plasticity contributes to the synergized strength and plasticity, and excellent phase stability is found in both solid solution and cold rolling conditions. The neural network structures of 3–1–1, 3–3–1 and 3–3–1 are built for elongation, yield and tensile strength, respectively, the average accuracy of which is up to 93.4% providing an outstanding agreement between predicted and experimental results. According to coefficients matrix measuring the importance of a parameter, the order of significant factors is reduction rate, annealing temperature and solutionizing temperature.
查看更多>>摘要：? 2022 Elsevier B.V.Exploring an appropriate and economical efficient cathode material for zinc ion batteries plays an important role in overcoming current existing challenges and realizing final practical application. A novelty explored phosphate ZnMn2(PO4)2 coated by a thin carbon layer [ZnMn2(PO4)2 @C] was synthesized and employed as cathode material for both aqueous and nonaqueous zinc storage system, featuring with a tunnel structure and working as a host for the Zn2+ extraction and insertion. It shows a reversible specific capacity of 67 mA h g?1 in 1 M Zn(CF3SO3)2 aqueous system. When coupling with FePO4, the full batteries containing ZnMn2(PO4)2 @C presented a capacity of 174 mA h g?1 with a high voltage plateaus of 1.17 V vs. Zn/Zn2+ in Zn(TFSI)2 nonaqueous electrolyte. The Zn2+ diffusion behavior for ZnMn2(PO4)2 contributes the main electrochemical process and the diffusion coefficient is in a scope of 10?11–10–14 cm2 s?1 for aqueous system and 10?12–10–14 cm2 s?1 for nonaqueous system, respectively. Combined with the high thermal stability, the low ion apparent activation energy and high diffusion coefficient can guarantee the superior electrochemical performance. A new phosphate family member for next-generation aqueous and nonaqueous zinc ion batteries was explored.
查看更多>>摘要：? 2022 Elsevier B.V.Layered P-type structures are integral to most competitive cathodes for sodium-ion batteries (SIBs). However, the performance of P2-type cobalt-based layered materials is unsatisfactory owing to a low initial discharge capacity caused by Na deficiency. Here, Mn-doped NaxCoO2 with a P3 structure is synthesized by using a modified solvent-thermal method with calcination. A structural analysis shows that partial Mn doping can effectively control P3 phase formation and increase D-layer spacing, thereby improving the diffusion of Na+. In addition, enhanced electrochemical performance is observed in optimized P3-type Na0.26Co0.48Mn0.52O2(NCMO-1), which exhibits a reversible specific capacity of 64 mAh g?1 at 3 A g?1 and a good capacity retention of 58% after 500 cycles. Furthermore, the Na-ion full cell constructed with an NCMO-1 cathode and a hard carbon anode yields a competitive energy density of 175.9 Wh kg?1 at 0.4 A g?1 with excellent cycle stability. Thus, this work provides a new viewpoint on the development of P3 structural materials with higher electrochemical performance for SIBs.
查看更多>>摘要：? 2022 Elsevier B.V.The precipitation behavior of M23C6 carbides in LF25 high nitrogen austenitic heat-resistant steel was investigated from 700 °C to 850 °C. The results demonstrated that the precipitates in LF25 steel included Nb (C, N) and M23C6 during the aging treatment. M23C6 carbides with four morphologies formed during aging followed a sequence of intergranular precipitates, parallel plate-like precipitates, cellular precipitates, and intragranular precipitates with increasing aging temperature. The four types of morphologies of M23C6 retained a cube-on-cube crystallographic relation with the matrix. Firstly, the M23C6 precipitated as discontinuous particles along the grain boundaries due to the faster diffusion rate of the elements. With the aging temperature increasing, intergranular M23C6 grew and connected to form a film-like morphology. The partial dislocations slipped out from the non-coherent twin boundaries due to the stresses resulting from quenching and elastic modulus together with atomic volume difference between the M23C6 and austenite matrix. M23C6 nucleated at the slipped dislocations and grew along the (111) or (110) planes to form a parallel plate-like morphology. Cellular precipitates were precipitated from supersaturated austenite matrix and then formed an alternating morphology of lamellae M23C6 and austenite during the discontinuous precipitation reaction. Due to high resistance to intracrystalline growth, the intragranular precipitates were short rods or granules with small sizes.
查看更多>>摘要：? 2022 Elsevier B.V.In the present work, microstructural evolution, and mechanical behavior of a novel high entropy alloy (HEA) are investigated through thermo-mechanical processing. The homogenized samples possess a single-phase cubic structure with high ductility. The rolled and subsequently annealed samples at various treatment conditions exhibit multi-phase microstructures. This study confirms that the sigma phase contribution becomes more significant on the mechanical response at higher annealing temperatures. Effects of phase distribution and degree of recrystallization on the microstructural evolution are examined in detail to probe the variation in the mechanical response. Samples subjected to annealing exhibit transformation-induced plasticity (TRIP) under plastic deformation. As such, the designed TRIP-assisted multi-phase HEA enables a combination of 1 GPa yield strength and about 10% of strain at failure.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, we have investigated the effect of Bi surfactant on structural, morphological and optical properties of 5 monolayers self-assembled InGaAs quantum dots (QDs) grown on GaAs (001) substrates at various growth temperatures (435, 467 and 495 °C) by Molecular Beam Epitaxy. Two types of InGaAs QDs samples grown with and without exposure to bismuth were studied using Atomic Force Microscopy, Scanning Electron Microscopy, Transmission Electron Microscopy and Photoluminescence (PL). Our results have demonstrated that Bi-mediated growth provides improved control of several properties of InGaAs QDs including an enhancement of the QD PL peak intensity by 1.7 times as compared to InGaAs/GaAs control sample grown without Bi. In addition, a red-shift of the PL peak energy of about 40 meV was also observed when the InGaAs QDs were grown by using Bi evidencing that Bi surfactant affects considerably the size of QDs. Furthermore, the QDs grown with Bi surfactant exhibited a higher degree of size uniformity as demonstrated by the observation of narrower Full Width at Half Maximum (FWHM) of the PL peaks. We have also shown that both Bi surfactant and substrate temperature play an important role to control the density of InGaAs QDs. The QD density decreased from 8.9 × 1010 cm?2 (control sample) to 2.0 × 1010 cm?2 for the sample grown at the lowest temperature of 435 °C under Bi flux. All these approaches to control and improve the properties of self-assembled QDs are important for device applications that require high optical efficiency and low QD density.
查看更多>>摘要：? 2022 Elsevier B.V.New noncentrosymmetric alkali rare-earth double borate Rb3SmB6O12 was found in the ternary system Rb2O–Sm2O3–B2O3. The Rb3SmB6O12 powder was prepared by the solid state reaction method at 750 °C for 40 h and the crystal structure was obtained by the Rietveld method. Rb3SmB6O12 crystallized in space group R32 with unit cell parameters a = 13.4874 (3) and c = 30.9398 (6) ?, V = 4874.2 (2) ?3, Z = 15. In the three-dimensional framework structure of Rb3SmB6O12, each [B5O10]5? group is linked to four different Sm-O polyhedra and, likewise, each Sm-O polyhedron is connected to four neighboring [B5O10]5? groups. The Sm-O polyhedra are formed by the face-sharing linked SmO6 octahedra. Rb+ cations are located in large cavities of the framework structure. From the thermal stability measurements, the incongruent melting of Rb3SmB6O12 is observed at 1104 K with as high melting enthalpy as Hm = –161.5 J/g. The nonlinear optical response of Rb3SmB6O12 tested via SHG is estimated to be similar to that of K3YB6O12. The Raman spectrum of Rb3SmB6O12 is mainly governed by the vibrations of BO4 and BO3 borate groups observed over the wavenumber range of 287–1550 cm–1. The spectral bands below 270 cm–1 were attributed to rotational, translational and mixed vibrations of Rb3SmB6O12 structural units. The luminescence spectrum of Sm3+ ions in the specific local environment of the Rb3SmB6O12 crystal lattice shows the ability to control the individual band intensity ratio originating from 4G5/2 level.
查看更多>>摘要：? 2022 Elsevier B.V.High-efficient and low-cost oxygen evolution reaction (OER) electrocatalysts are of considerable significance for large-scale electrocatalytic water splitting to produce hydrogen. In this work, we have introduced O2 plasma to engineer Fe-doped Ni2P (Fe-Ni2P) nanosheets, which is grown on the conductive NiFe foam. Interestingly, this facile and rapid plasma treatment can simultaneously achieve defect engineering (P vacancies) and the formation of new species (phosphate). The P vacancies could modulate the electronic structure of the electrocatalyst for the OER process, while the formed phosphate species could facilitate water adsorption and improve the charge transfer. Consequently, the O2-plasma treated Fe-Ni2P nanosheets with rough surface and nanoholes exhibit low overpotentials of 207 and 218 mV at 50 and 100 mA cm?2, small Tafel slope of 45 mV dec?1 and excellent durability in alkaline electrolyte. Our work reveals the delicate structural transformation of the plasma-engineered material, and provides insights of the structure-property relationship of high-performance OER electrocatalyst.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, we report a ZnO@Ti3C2 MXene composite obtained using a simple hydrothermal method for increasing the photocatalytic degradation ability of methylene blue (MB). When the addition amount of Ti3C2 MXene is 50%, the ZnO@Ti3C2 MXene composite exhibited the best photocatalytic degradation performance (94.84%), and the reaction rate constant is 0.01223 min?1, which is 47 and 30 times of pure ZnO (5.59%, 0.026 ×10–2 min?1) and pure Ti3C2 MXene (7.56%, 0.04050 ×10–2 min?1), respectively. Moreover, the ZnO@Ti3C2 MXene composite exhibited good stability. The photocatalytic mechanism of ZnO@Ti3C2 MXene composite is proposed. The addition of Ti3C2 MXene forms a Schottky junction between ZnO and Ti3C2 MXene. The Schottky junction prevents the photogenerated electrons from returning to ZnO and promotes the separation of photogenerated electrons and holes, thus effectively improving the photocatalytic performance of ZnO@Ti3C2 MXene composite.
查看更多>>摘要：? 2022 Elsevier B.V.Hydrolysis of LiBH4 (LB in short) is considered as a potential means of releasing the hydrogen stored in the hydride and the water. However, the hydrolysis of LB occurs only above 0 °C and efficient catalysts are required to accelerate the hydrogen kinetics. Here, we demonstrate an efficient non-catalytical hydrogen generation system that enables H2 production of LB over a wide range of temperatures with methanol (referred to MeOH), ethylene glycol, and MeOH/water mixtures as reaction solvents. The results indicate that the hydrogen kinetics of LB is controllable by MeOH dose, MeOH species, reaction temperature, and solution components. For instance, the hydrogen evolution rate could be accelerated from 266 to 515 mLH2 min?1 g?1 (per unit weight of LB) with a H2 yield up to 93% by tailoring the dose of methanol at 25 °C. Notably, the glycolysis kinetics is much faster than that for the methanolysis of LB, delivering a hydrogen rate varying from 523 to 10,125 mLH2 min?1 g?1. By optimizing reaction conditions, a gravimetric hydrogen density of ~4.6 wt% H2 was realized in the LB-MeOH system. Interestingly, the methanolysis/glycolysis products of LB can spontaneously convert into MeOH and hydrated byproduct (LiBO2?2H2O) by reacting with water, and MeOH may be separated and reused as an intermediate. Here, LiBO2?2H2O can be easily regenerated back to LB by ball milling with Mg under ambient conditions. Thus, a hydrogen cycle combining hydrogen generation and storage in a closed material cycle is achieved, which may lay the foundation for developing practical hydrogen sources for mobile/portable applications.
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