查看更多>>摘要：? 2022 Elsevier B.V.A novel L12/D03 biphase Fe-27Ga alloy with both high damping (0.007, equivalent to a specific damping capacity (SDC) of 0.04) and the near-zero (～?4 ppm) magnetostriction has been prepared by using an appropriate heat treatment process: annealing at 480 °C for 1 h. Here the L12 phase proportion is about 44.8%. More importantly, the damping mechanism of L12/D03 biphase Fe-27Ga alloy has been deeply studied based on the experiments of amplitude-dependent IF measurements with and without magnetic field, combined with the magnetostriction measurements. All the results indicate that for the L12/D03 biphase Fe-27Ga alloy, D03 phase with a magnetic damping plays a dominant role under a lower strain amplitude while L12 phase with a non-magnetic damping plays a main role under a higher strain amplitude. At the same time, the L12/D03 biphase Fe-27Ga alloy with more L12 phase has a higher damping capacity under a higher strain amplitude, which is mainly the non-magnetic damping contribution originated from the twin boundaries movement. This can provide a new way and design concept for high damping Fe-Ga alloys to satisfy more application requirements, such as micro-vibration field, strong vibration field, magnetic or non-magnetic field.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, amorphous Co-Cr-B/NG catalysts were prepared by the chemical reduction method. A descriptor of “valence band center” was introduced to the NaBH4 hydrolysis reaction to investigate the relationship between the valence band and the catalytic activity of amorphous Co-Cr-B/NG catalysts. The outcomes show that the valence band center of the Co-Cr-B/NG hybrids has been significantly changed after the Cr content is regulated by the preparation process, which can facilitate the modulation of the electronic structure of the catalysts. The hydrogen release rate shows a shape of a volcano with the valence band center. The hydrolysis performance test results of the optimum catalyst demonstrated that the hydrogen release rate of NaBH4 water at 25 °C was 2231.7 mL·min?1·g?1 with an activation energy of 38.41 KJ·mol?1, according to the volcano curve.
查看更多>>摘要：? 2022 Elsevier B.V.The hydrogen-absorbing alloys currently used in industry form residual hydrogen that reduces the alloy's reversible hydrogen capacity, decreasing its useful life. RNi3 intermetallic compounds, which have a PuNi3-type crystal structure composed of MgZn2-type and CaCu5-type cells that exhibit structural change in relation to their hydrogenation properties, have been the focus of much research, but only a few of those reports focus on the interplay between residual hydrogen and alloy structure. Thus, this study seeks to clarify the residual hydrogen occupation mechanisms in MgZn2-type and CaCu5-type cells during the hydrogen absorption-desorption process. The structural changes and deuterium occupation in NdNi3Dx were investigated using X-ray diffraction (XRD) and neutron powder diffraction (NPD). Rietveld refinement was performed for NdNi3, NdNi3D2.6, NdNi3D3.2, NdNi3D4.0, and NdNi3D4.8, during the deuterium absorption-desorption process. The deuterium capacity reached 0.9 D/M at the first absorption process and 0.7 D/M of residual deuterium was formed after the first desorption at 248 K. For NdNi3D2.6 (phase II), the residual deuterium contents of MgZn2-type and CaCu5-type cells were determined to be 1.0 D/M and 0.4 D/M, respectively. The residual deuterium preferred the deuterium site in the MgZn2-type cell. The deuterium capacity was 1.2 D/M in the first absorption process at 213 K and the residual deuterium was 1.0 D/M at the end of the first desorption. The severe peak broadening observed in the XRD and neutron diffraction patterns of NdNi3D4.0 and NdNi3D4.8 indicate that the deformation of the metal sublattice of the deuteride phase was deformed over 0.8 D/M.
查看更多>>摘要：? 2022 Elsevier B.V.Exploring better Gamma, X-Ray and IR-Mid-R detectors, adequately sensitive to ambient temperatures and environmental conditions, is highly desirable. Therefore, following this path, we present detecting opportunities, based on data of experimental and theoretical investigation of the electronic and optical properties, photocurrent behavior at different bias voltages as well as the reflection for the He-Cd cw laser after irradiation by three different IR laser wavelengths, for recently grown TlPb2BrI4 single crystal with strong anisotropic, two-dimensional (2D) layered structure. The X-ray photoelectron spectroscopy brings data on binding energy values of core levels of TlPb2BrI4 for both as-grown and Ar+-ion-treated crystal surfaces as well as for elucidation of the energy distribution of the valence electronic states. In opposite to well-known IR-detector materials, TlPb2BrI4 crystal surface shows high chemical stability concerning Ar+-ion bombardment. Further, we carry out ab initio band-structure calculations to gain curves of total and partial densities of states and to elucidate the principal optical constants of TlPb2BrI4. The present studies indicate that, in spite of the fact that the TlPb2BrI4 crystal contains two very hazardous/toxic chemical elements, thallium and lead; however, it is chemically stable and reveals very low hygroscopic behavior when being exposed to environmental conditions.
查看更多>>摘要：? 2022 Elsevier B.V.The microstructure adjustment of Ni-based superalloys focuses heavily on the types of precipitated phases because the failures of Ni-based superalloys often occur at γ-matrix/γ′- or γ′′-precipitated phase heterogeneous interfaces. As different types of precipitate phases result in different interface damage resistances, the influences of the types of precipitated phases on the damage resistances of heterogeneous interfaces were investigated in this work. Based on the results of this work, the interfacial works of adhesion for the three interfaces composed of the γ-matrix and typical precipitated phases (γ′-Ni3Al, γ′-Ni3Ti, and γ′′-Ni3Nb) are 4.81, 3.88, and 4.26 J/m2, respectively, indicating that the γ-Ni/γ′-Ni3Al interface shows the highest cleavage fracture resistance. This can be attributed to the highest interfacial average charge density among all three interfaces. During interface tensile processing, all fractures occur in the precipitated phase, indicating that the ductility of heterogeneous interfaces is determined by that of the precipitated phase. Due to the highest ductility of γ′-Ni3Ti, the γ-Ni/γ′-Ni3Ti interface demonstrates the best plastic fracture resistance with the smallest Rice ratio of 4.89 and the largest maximum strain of 10 %, followed by the γ-Ni/γ-Ni3Al and γ-Ni/γ′′-Ni3Nb interfaces. The γ-Ni/γ′-Ni3Ti interface also exhibits the highest fatigue fracture resistance attributed to its strongest ability in hindering dislocation slipping with the lowest unstable stacking fault energy, followed by the γ-Ni/γ′′-Ni3Nb and γ-Ni/γ′-Ni3Al interfaces. These results conclude that Ni-based superalloys with γ′-Ni3Al as the main precipitated phase demonstrate high strength, while those with γ′-Ni3Ti as the main precipitated phase demonstrate high plastic and fatigue fracture resistances.
Gokulkumar K.Wang S.-F.Jenisha Daisy Priscillal I.
10页
查看更多>>摘要：? 2022 Elsevier B.V.Nitrophenols (NPs) extensively used in the manufacture of pesticides, dyes, and pharmaceuticals are categorized as anthropogenic, lethal, and refractory compounds that require massive effects ardent to mitigate the devastating influences on the living environment. A novel, simple and cost-effective tactic to create a sensing platform with excellent electrochemical performance for rapid detection of 3-nitrophenol (3-NP) is necessary for human health and the environment. An electrochemical sensor constructed through a glassy carbon electrode modified by ZnS nanoparticles doped on functionalized CNF coated with PDA had been developed for the detection of 3-NP. The modification of the electrode gives excellent electrocatalytic action and virtuous selectivity towards the reduction of 3-nitrophenol due to its exceptional adsorptive ability, hefty active surface area, and electrical conductivity contributed by the synergism followed by ZnS and PDA@f-CNF. Under optimal experimental conditions, this newly fabricated sensor exhibits good linearity towards 3-NP concentration with a lower detection limit. Moreover, the ZnS/PDA@f-CNF sensor showed good repeatability, reproducibility, and stability. Further, effectual recognition of 3-nitrophenol in urine samples additionally benefits the real time monitoring and practicability of the proposed sensor.
查看更多>>摘要：? 2022 Elsevier B.V.A tunable nanocomposite structure, consisting of Ni nanoparticles (NPs) with various morphologies and controllable BaTiO3 (BTO) films, was designed using a pulse laser deposition method. The morphological transformation of NPs and the crystal structure of BTO could be modulated by the Ni NP concentration. The experimental demonstration of absorption and photoluminescence enhancement using surface plasmon resonance (SPR) excitation in the deep-ultraviolet (DUV) region was investigated. The splitting of the Ni SPR peak was found in the DUV region, accompanied by decreased band gaps as the Ni NP concentration increased. By photoluminescence analysis, more Ni NPs embedding could provide more electron-hole recombination possibilities, enhancing the optical emission intensity and widening the emission range from red to ultraviolet luminescence. The DUV optical response of Ni NPs with various morphologies was further verified by finite-difference time-domain calculations. Compared with the reported metal NPs using the DUV SPR effect, the smaller Ni NPs provide a new non-noble metal NPs alternative with a high performance SPR excitation in the DUV region beyond the previous Al-based materials, giving new opportunities for manipulating high-energy photons.
查看更多>>摘要：? 2022The present work reports one-pot modified Pechini synthesis of porous Co3O4-CeO2 (CC) nanostructures with the templating environment of succinic acid, and further it is decorated with graphitic carbon nitride (g-C3N4 or CN) substrate. Interfacial architecture of the multicomponent nanocomposites can promote the synergistic effect by adjusting the weight percent of CC guest (30%, 50% and 70%) into CN host. The consequent changes in the compositional, morphological features and porosity of the resulting composites are unraveled by a combination of XRD, Raman, FE-SEM, HR-TEM, and BET analyses. Remarkably, the redox reactivity and considerable electronic conductivity of nanostructured electrode materials ascertains by cyclic voltammetry (CV) and chronopotentiometry charge–discharge (CCD) techniques in 2.0 M KOH medium. Fabricated Co3O4–CeO2/g-C3N4 (CC-CNx%) nanocomposites proved as the energetic electrode materials for realizing hydrogen storage performance at current of 1 mA. It is demonstrated that the CC/Cu platforms can produce the discharge efficiency of 619.25 mAhg?1 after 15 cycles. However, among the various adding, the ternary nanocomposites with 50.0 wt% CC nanoparticles achieved the higher discharge capacity of about 1020.53 mAhg?1 in three electrode cell. The coupling effect of interfacial architecture presented here suggests alternative insights into constructing uniformly nanocomposites for highly efficient energy storage applications.
查看更多>>摘要：? 2022 Elsevier B.V.Heterostructure electrolytes made of semiconductor and ionic conductor have drawn significant attention in solid oxide fuel cells (SOFCs) field owing to their attractive ionic conductivity at low operating temperatures. In this study, a new heterostructure is proposed by introducing a layered semiconductor NaCo0.5Fe0.5O2 (NCF) into fluorite structure ionic oxide CeO2 for SOFC electrolyte uses. The prepared samples are characterized in views of phase structure, surface and interface property, and electrical conductivity, followed by being applied in SOFCs for performance, impedance spectra and durability assessment. It is found the NCF-CeO2 forms nanoscale heterostructure with massive hetero-interfaces and enriched oxygen vacancies. The best-performing sample 35NCF-65CeO2 gains improved ionic conduction and promising SOFC performance with power density of 68–1010 mW cm-2 at 350–550 °C. Moreover, durability measurement verifies the NCF-CeO2 based SOFC can be stably operated for 160 h under fixed current density of 100 mA cm-2, whereas there is an obvious degradation in the initial 5 h. A particular attention is paid to investigate the dynamic electrochemical process and junction rectification effect of the NCF-CeO2 cell to interpret the degradation behaviour. Our findings thus certify the great promise of layered and fluorite oxide based NCF-CeO2 nanoscale heterostructure for low-temperature SOFC electrolyte uses.
查看更多>>摘要：? 2022InGaN-based multiple quantum wells (MQWs) embedded nanoporous (NP) GaN layers were fabricated by metal-organic chemical vapor deposition (MOCVD) and followed by electrochemical (EC) etching in oxalic, HF or HNO3 electrolytes. The oxalic-etching and HF-etching do not lead to enhanced luminescence of MQWs, which should be contributed to the damage of InGaN/GaN stacking layers. For the HNO3-etching, the photoluminescence (PL) strength of MQW layer is increased by a factor of 0.52 compared with the as-grown sample, which should be contributed to stress relaxation, light scattering and reflection of quasi vertical nanopore array, and amplify spontaneous emission by resonant cavity. If the nanopore walls in NP-GaN layer are smoothed by the annealing in NH3 atmosphere, the light extraction efficiency of MQWs can be further improved. The study provides a useful method for improving the light extraction efficiency of GaN-based light emitting devices.
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Elsevier