查看更多>>摘要：Three distinct initial microstructures, including the coarse grains (Al0 sample), fine grains (Al0-T sample) and fine grains with particles (Al0.3-TA sample), are prepared to investigate the deformation substructure development in AlxCoCrFeNi (X = 0, 0.3) high entropy alloy under the different influencing factors (grain size, strain temperature, strain level and particle). Results suggest slip dislocation is recognized in all deformed samples under the different strain conditions, while the strain temperature and the strain level are the critical factors for producing deformation twins for Al0 sample and Al0.3-TA sample, respectively. The effect of slip dislocation on deformation substructure development in Al0 sample is investigated via analyzing how orientation spread builds up inside the grains, confirming three different kinds of dislocation induced deformation patterns. The main difference between annealing twins and deformation twins are systematically investigated, revealing the different morphological features and the different number of activated twin variants. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, we prepare a kind of supercapacitor (SC) through all-in-one assembled method with redoxactive ionogel electrolyte and carbon paper electrodes. The ionogel is compounded with poly (vinyl alcohol) (PVA), polyacrylamide (PAAM), lithium sulfate (Li2SO4), and 1-butyl-3-methylimidazolium bromide ionic liquid (BMIMBr IL). The device reveals outstanding long-term stability of 99.6% percent after 5000 times charge/discharge test in high current density, which is largely owed to the all-in-one method and low loss rate of ionogel that provides confined space, stable structure and good contact between electrodes and electrolytes interfaces. Due to the existence of double cross-link structure, ionogels exhibit excellent mechanical properties, which are proved by bending tests of flexible devices. Additionally, wide potential window of 1.6 V and pseudocapacitance provided by bromide ions redox reaction (Br-/Br-3(-)) make the device have a relatively high area capacitance of 284.8 mF cm(-2) in the activated carbon field. Moreover, the device also possesses a high energy density of 25.3 Wh kg(-1) with the power density of 99.8 W kg(-1) at 0.5 mA cm(-2) current density. (C) 2021 Elsevier B.V. All rights reserved.
Naumov, S. P.Mushnikov, N., VTerentev, P. B.Oshtrakh, M., I...
7页
查看更多>>摘要：To ascertain the nature of the magnetostructural phase transition in Ce(Fe1-xSix)(2) compounds with low silicon content, which crystalize into the structure of cubic Laves phase, we studied local structure peculiarities using high-precision Fe-57 Mossbauer spectroscopy (with a high discretization of the velocity reference signal). Unlike the earlier published works on this type of compounds, in the study presented, the occurrence of at least two different types of local surrounding of Fe atoms in the binary compound CeFe2 and non-random Si distribution in the Ce(Fe1-xSix)(2) crystal structure is reported for the first time. To specify the type of ordering of Si atoms, the experimental data are compared with results of mathematical simulation of different types of ordering, and, in this way, a conclusion on the mechanism of magnetostructural phase transition is made. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The MgH2-Nb2O5-carbon nanotube (CNT) composite was fabricated to accommodate the volume change of particles during the hydrogen storage cycles by holding the MgH2-Nb2O5 particles within the sponge-like matrix of the CNT. This allowed for preservation of the composite structure and led to more stable hydrogen sorption properties during 20 cycles, as compared to without CNT. To investigate this effect of CNT on the cyclic stability of MgH2-Nb2O5, CNT and expanded graphite (EG) were added to MgH2-Nb2O5 via ball mil-ling. The MgH2-Nb2O5-CNT powder showed stable cyclic performance, similar to the MgH2-Nb2O5-CNT composite, whereas the MgH2-Nb2O5-EG powder exhibited cyclic degradation similar to MgH2-Nb2O5. From SEM-EDS, it was found that the C/Mg ratio of the surface of the MgH2-Nb2O5-CNT powder was higher than that of the MgH2-Nb2O5-EG powder. Thus, the fibrous CNT on the surface of the MgH2 particles could be responsible for the greater cyclic stability of the MgH2-Nb2O5-CNT composite. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Developing highly efficient earth-abundant catalysts for the electrochemical oxygen evolution reaction (OER) is essential to promote the commercial application of water splitting. Herein boron-doped cobalt-iron bimetal phosphides nanosheets as OER electrocatalysts have been successfully prepared by hydrothermal boronation of bimetallic metal-organic frameworks precursors with the subsequent low-temperature phosphidation. The synergistic effect between non-metal elements (B and P) and metals (Co and Fe) is found to play an important role on tuning the local electronic configuration surrounding the active metal centers. Moreover, the resultant nanosheet structures are beneficial for exposing the catalytically active sites and facilitating the mass/charge transport. As expected, the optimal catalyst exhibits superior catalytic performance toward the OER with long-term durability in 1.0 M KOH, affording a current density of 10 mA cm(-2) at low over-potential of 294 mV and small Tafel slope of 49.5 mV dec(-1). (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Nickel-based single crystal superalloys reveal obvious anisotropy and orientation correlation. Choosing the orientation with the best mechanical properties is beneficial to prolong its service life. In this paper, the effects of crystal orientation on the plastic deformation and mechanical properties of the nickel-based single crystal two-phase model under uniaxial tension/compression were simulated by molecular dy-namics. The microstructure evolution and dislocation movement are studied through stress-strain response and structural changes of the two phases with different crystal orientations. In addition, the typical dis-location structures are analyzed, it is found that the yield stress of different orientation models is: [111] > [001] > [011]. Different orientation models all show tension/compression asymmetry and the [001] orientation is the most obvious. The results showed that the evolution of dislocation and stacking faults is one of the reasons which causes the crystal anisotropy. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：In this study, we investigated the microstructures and mechanical properties of Mg-6Gd-1Er-0.5Zr (GE61K) sheets. The results show that the rolling temperature has a remarkable influence on microstructures, age-hardening responses and mechanical properties of GE61K sheets. The microstructures varies with the increase in rolling temperatures, i.e. microstructures were dominated by the mixture of dynamic re-crystallized (DRXed) grains and un-DRXed grains at 300 degrees C, by DRXed grains at 350 degrees C, and by un-DRXed grains at 400 degrees C and 450 degrees C. Rolling at 300 degrees C leads to a formation of the bimodal microstructure which contains equilibrium Mg-5(Gd, Er) precipitates and a large number of dislocations. These dislocations leads to a formation of novel chain-like precipitates which comprise dominant beta', beta'(F) (or beta'(T)), tail-like "hexagonal ring" layers, individual "zig-zag" chain and individual "hexagonal ring", eventually improving age-hardening responses. The chain-like precipitates are beneficial for achieving a good strength-ductility balance by dividing the matrix into nano-scale units and forming subsequent honeycomb structures. As a result, the R-300 degrees C sheet shows good mechanical properties, i.e. ultimate tensile strength (UTS) of 367 +/- 3 MPa, yield strength (YS) of 349 +/- 4 MPa and elongation (EL) of 9.1 +/- 1.5%, respectively. However, such strength-ductility balance is destroyed sharply as soon as the rolling temperature increases to 400 degrees C because of the microstructure variations. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Constructing plasmonic-semiconductor nanoarchitecture provides a photocatalytic platform for enhancing solar energy conversion. The excitation and extraction of energetic carriers are critical for improving energy efficiency, which can be affected by the geometric features of plasmonic structures. An extensive study on morphology dependent hot electron utilization is desirable but challenging. In this paper, we applied photocurrent response from the microscale reaction region on Au-TiO2 photoanode to evaluate the influence of plasmonic morphology in water splitting. We compared the photocurrent of two structures, gold nanospheres and nanorods, under visible illumination. We experimentally proved that the nanorods demonstrate better energy performance. The possible origins of this enhancement are ascribed to the sharp curvature at tips, where strong hot spots boost the generation and injection efficiency of hot electrons. These results may pave a way for a rational geometry design for plasmonic enhanced photocatalysis. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：Erbium (Er) doped P2O5-K2O3-Al2O3:Er2O3 glasses (KPEr) with different contents of Er3+ ions were fabricated by famous melt-quenching technique. The fabricated samples were characterized by using physical, X-ray photoelectron spectroscopy (XPS), photoluminescence, absorption, and J-O analysis techniques. The XRF analyses were performed in order to know the change in elemental composition of fabricated glasses, while using the various concentrations of Er3+ ions. Three emission peaks were observed, two peaks in visible regions of 526 nm (H-2(11/2) -> I-4(15/2)) and 550 nm (S-4(3/2) -> I-4(15/2)) and one peak in near infrared (NIR) region of 1545 nm (I-4(13/2) -> I-4(15/2)). Nine peaks were observed in absorption spectra in the range of 390-1800 nm. The trend of JO parameters for the present KPEr6 glass sample is Omega(2) > Omega(4) > Omega(6). Higher values of stimulated emission cross-section sigma(emi)(lambda), full wave half maxima FWHM and (FWHM x sigma(emi) (lambda)), for KPEr6 indicate that the present glass has potential candidate to be used for broadband amplification in telecommunication. The McCumber theory is used to study absorption and emission cross-section for I-4(13/2) -> I-4(15/2) transition. The luminescence colors of these samples were almost entirely fall in the yellow green (Y-G) region (x = 0.33, y = 0.64) in the CIE 1931 diagram. The calculated CCT values for our prepared glasses were found to be 5554 K. The present study suggest that KPEr glass samples have potential candidate for broadband amplification in telecommunication, green LED and display devices. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Developing low-cost and highly effective electrode materials is crucial for advanced supercapacitors. In this work, N-doped graphene with an interconnected porous structure is prepared with a solvothermal method combined with freeze-drying. The hierarchical porous structure with a large specific surface area (291.3 m(2) g(-1)) and high total pore volume (0.418 cm(3) g(-1)) offers many adsorption sites and fast transfer channels for electrolyte ions, enhancing the supercapacitive performance. Also, the intrinsic oxygen and the doped nitrogen (9.95 at%)-based functional groups increase the hydrophilicity of the as-prepared electrode material and provide the additional pseudo-capacitance, further improving the supercapacitive behavior. Under the present conditions, the optimal graphene (denoted as hp-NGR-1.0), which is fabricated by using 1.0 mL of tetraethoxysilane, possesses a specific capacitance of 328.5 F g(-1) at 1.0 A g(-1) in the three-electrode device, and the corresponding symmetric configuration displays an energy density of 31.2 Wh kg(-1) at 400 W kg(-1), which is superior to many previous results. Also, the optimal material depicts good cycling stability and rate capability. The prominent properties endow hp-NGR-1.0 promising potentials in the fields of high-performance electric energy storage devices. (C) 2021 Elsevier B.V. All rights reserved.
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