查看更多>>摘要：High entropy alloys (HEAs) have attracted considerable attention due to their excellent mechanical properties, which provides new insights for designing next generation structural materials. A series of Al_(0.2)Co_(1.5)CrFeNi_(1.5)Ti_(0.5)B_x (x = 0, 0.15, 0.3, 0.45, 0.6, 0.75 and 0.9, in molar ratio) HEAs was prepared by vacuum arc melting to investigate the effect of boron doping on the phase evolution, microstructure transformation and mechanical properties. The results indicated that the HEAs with trace boron doping (x = 0.15) maintained single FCC phase, while it evolved to FCC phase, in-situ borides (TiB_2 and Cr_2B) and Laves phase when the boron molar ratio higher than 0.3. With the boron molar content increased from 0 to 0.9, the microstructures of the HEAs transformed from complete dendrite to dendrites, irregularly shaped TiB_2, needle-shaped Cr_2B and lamellar eutectic structure which composed by alternate layers of FCC phase and Laves phase. B doping improved the strength and hardness of the HEAs. The enhanced mechanical properties of the boron doped HEAs was attributed to the synergistic strengthening effect among interstitial solid solution strengthening, second phase strengthening, dislocation strengthening, fine grain strengthening and heterostructure strengthening.
查看更多>>摘要：The hybrid structure of high conductive carbon materials with large capacitive metal compounds is one of promising strategies for achieving high specific capacity, cycling stability, and ultrafast Li-ion storage capability due to their synergistic effects. This article will demonstrate the novel hybrid structure of a zinc oxysulflde (ZnOS) lamination layer on a sulfur (S)-doped carbon nanofiber (SCNF) matrix via an electro-spinning method with sequential atomic layer deposition (ALD) process and will also present the structural advantages for ultrafast Li-ion batteries (LIBs). As a double-anion material, ZnOS has benefits compared with single ZnO and ZnS during the charge/discharge process, which is accompanied with consecutive conversion and alloying reactions. To verify these factors, structural analysis at the atomic scale and various electrochemical properties were evaluated. The resultant ZnOS/SCNF electrode showed superior electrochemical performance such as high specific capacity (672.8 mAh g~(-1) at 100 mA g~(-1)), good capacity retention (87.8% after 100 cycles), and excellent cycling stability (85.4% after 500 cycles). This is attributed to the facilitated kinetic properties including electron and ion transfer efficiency during the electrochemical reactions, accompanied with the ZnOS/SCNF hybrid structure. In this regards, we believe that the ZnOS/SCNF electrode could be a great reference as a promising research strategy for accomplishing ultrafast LIBs.
查看更多>>摘要：The effects of Y and LaCe substitution in Nd-Fe-B multi-main-phase (MMP) magnets were investigated by co-mixing with the binary or ternary components. The microstructure and magnetic properties showed some differences after Y and LaCe-substitution. The coercivity was increased for the LaCe-substituted MMP magnets with two-types shell structures due to the stronger magnetic isolation between adjacent grains. Y-substituted MMP magnets with one-type shell structure exhibited a relatively lower coercivity due to the deterioration of anisotropy owing to the La/Ce/Y enrichment in the core-shell structure. The La element preferred to migrate to the grain boundary regions in the LaCe-substituted MMP magnets, while it was trapped in the 2:14:1 shell by the inducement of Y in the Y-substituted MMP magnets. This work provides new insights into the fabrication of La/Ce/Y magnets with high performance.
查看更多>>摘要：In this study, a 2 at% erbium doped cerium trifluoride (Er:CeF_3) single crystal was grown using the Bridgman method. The consequent absorption, infrared transmittance, and fluorescence spectra were recorded. The spectroscopic properties of Er:CeF_3 crystals were intensively studied based on the Judd-Ofelt (J-O) theory. The Ω_2, Ω_4, and Ω_6 parameters were fitted to be 5.206 × 10~(-20), 1.805 × 10~(-20), and 3.06 × 10~(-20) cm~2, respectively. The emission cross-section centered at 1564.6 nm was calculated to be 1.053 × 10~(-20) cm~2, and the corresponding fluorescence lifetime was measured to be 1.675 ms. Additionally, the magneto-optical (MO) performance of the Er:CeF_3 crystal was investigated for the first time. The Verdet constants of Er:CeF_3 at 532, 632.8, 1064, and 1310 nm are 231.0,165.4, 43.4, and 24.4 rad-T~(-1)-m~(-1), respectively, which are significantly higher than those of pure CeF_3 and traditional Tb_3Ga_5O_(12). The results show that the Er:CeF_3 crystal can be applied both to solid-state lasers and Faraday devices.
查看更多>>摘要：In this study, hollow cubic Cu_2MoS_4 nanoparticles were synthesized via a facile hydrothermal method. Following that, Rh single atoms were loaded onto the surface of Cu_2MoS_4 nanoparticles to prevent electron/ hole recombination. The cubic morphology of Cu_2MoS_4 nanoparticles and the presence of Rh atoms were investigated by Transmitting Electron Microscope (TEM). The crystal structure of the synthesized Rh-loaded Cu_2MoS_4 was studied by X-ray diffraction (XRD). The shift in Rh X-ray Photoelectron Spectroscopy (XPS) peaks indicated the intimate interaction between Rh and Cu_2MoS_4, providing a pathway for the charge transfer. The photocatalytic efficiency of the synthesized photocatalysts was significantly enhanced by introducing Rh single atoms onto the Cu_2MoS_4 surface. Consecutive photocatalytic dye degradation experiments revealed that Rh-loaded Cu_2MoS_4 nanoparticles could be recycled and reused multiple times with no drop in the photocatalytic efficiency. The improved photocatalytic performance of Rh-loaded Cu_2MoS_4 was attributed to a lower charge transfer resistance, higher charge transfer rate, and longer charge carrier lifetime. The most crucial reactive radical was detected to be O_2~-~ while e~- and h~+ are also playing an essential role in the photocatalytic degradation of RhB on Rh-loaded Cu_2MoS_4. This study highlighted the importance of forming a Schottky junction between Rh and Cu_2MoS_4 to enhance charge carrier separation and improve photocatalytic efficiency.
查看更多>>摘要：Zn-0.2Mg-(0, 0.05, 0.2, 0.4 wt%)Fe alloy rods were produced by indirectly extruding the as-cast ingots at 200 °C. The addition of minor Fe significantly improved the ductility of as extruded Zn-0.2Mg alloy without scarifying the strength. As 0.05 wt% Fe was added, the yield strength, ultimate tensile strength and elongation were increased from 216 MPa, 228 MPa and 1.85% for Zn-0.2Mg alloy to 240 MPa, 258 MPa and 42% for Zn-0.2Mg-0.05Fe. Texture variation from basal texture to non-basal texture alongside the grain refinement contributed the great improvement of ductility and slight increase of strength, respectively. As Fe content increased from 0.05 wt% to 0.4 wt%, the volume fraction and size of the second phases changed, leading to the reduction in elongation by 50% yet maintaining the yield strength and ultimate tensile strength.
查看更多>>摘要：The paper aims to develop an excellent soft magnetic glassy alloy with a series of (Fe_(1-x)Ni_x)_(79)P_5B_(12)Si_3C_1 (x = 0, 0.2, 0.4, 0.5, 0.6). The annealing at (T_g-20) K for the 0.4Ni-0.5Ni alloys causes an extremely low coercivity below 1 A/m with very high effective permeability above 5-10~4 at 1 kHz in the maintenance of high saturation magnetic flux density of ≌ 1.2 T. Good effective permeability characteristics were recognized as is evidenced from high μ_e values above 6000 at 1 MHz. The core losses at induction of 100 mTare as low as 43 W/kg for 100 kHz and 1150 W/kg at 1 MHz for the annealed 0.6Ni alloy. Excellent soft magnetic properties are presumably due to the achievement of the fully relaxed glassy state which can be obtained only for the glass-type alloys with SCL region. This complex of magnetic properties is promising for future use as high-frequency type soft magnetic materials.
查看更多>>摘要：Currently, ail-inorganic halide perovskites are widely investigated for their applications in optoelectronics due to their excellent physical and chemical properties. In this paper, solution-processed bulk-hetero-junction lateral photodetectors Ag/CsPbBr_3:ZnO/Ag were built to enhance device performance, in which the active CsPbBr_3 layer were surface-passivated by ZnO nanoparticles (NPs) in an optimized molar ratio. By optimizing the molar ratio of CsPbBr_3 to ZnO NPs (i.e. fcR=M_(CsPbBr_3)/M_(ZnO)). the photocurrent from the lateral photodetector was greatly enhanced and, the dark current was suppressed to as low as 10~(12) A due to the lateral configuration by employing a 50 pm-width active layer made through an interdigital mask. As a result, the On/Off current ratio of the lateral photodetector Ag/CsPbBr_3:ZnO/Ag reaches to more than 10~3 for an optimum molar ratio k_R= 1:1, and it is 300-folds higher than that of the control device Ag/CsPbBr_3/Ag, showing a maximum specific detectivity D* of 1.6 × 10~(11) Jones with a photoresponsivity of 3.8 mA/W under 16 pW/cm~2 405 nm illumination at - 5 V. In this way, it provides an efficient method for solution-processed high-performance photodetectors by combining bulk heterojunction and lateral configuration.
查看更多>>摘要：The mesoporous network of γ-Al_2O_3 ceramic support was coupled with the two dimensional (2D) hexagonal CdO nanoplates by ultrasonic assisted method. The fabricated photocatalyst was analyzed for its structural, morphological and optoelectrical properties by employing X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), photoluminescence, electron spin resonance (ESR) analysis and electrochemical impedance spectroscopy (EIS). The X-ray powder diffraction (XRD) result supports the good crystallinity of the fabricated nanohybrid with co-existence of pure phases of γ-Al_2O_3 and CdO nanoparticles (NPs). The nanohybrid was tailored to narrow down the bandgap to visible-light region. The bandgap energy obtained by UV-visible diffuse reflectance spectroscopy (DRS) for CdO/Al_2O_3 nano-composite (NCs) was 2.95 eV. The Brunauer-Emmett-Teller (BET) surface area analysis shows porosity of material with high surface area. During photocatalysis, e" from CdO migrates to defect levels of A1_2O_3 that facilitated charge separation. The kinetic rate of degradation of methylene blue (MB) by NCs was 3.5 and 14 times higher than CdO and A1_2O_3 respectively. The performance was optimized and it showed good reusability. In addition, the multiple applications of the CdO/Al_2O_3 were evaluated by testing the bactericidal activity. The nanohybrid posed high growth inhibition activity towards both gram positive and negative bacterial strains. The maximum colour removal (97.3%) and high mineralization (87%) was verified by UV-visible and total organic carbon (TOC) measurements. This promotes the nanohybrid to act as a better candidate for environmental remediation and disinfectant applications.
查看更多>>摘要：Here a facile hydrothermal method was developed to prepare heterogeneous photocatalyst constructed by decorating nanorod-assembled orbicular WO_3-0.5 H_2O on the surface of porous carbon nitride nanosheets. By integrating two martials with synergetic effect according to their bandgap structure, as-obtained catalyst exhibits well-suppressed recombination of the photoexcited carriers by formation of Z-scheme bandgap structure. It, together with the increased surface areas, contributes to the significantly improved photo-catalytic performance. As a result, the heterogeneous photocatalyst reveals a hydrogen generation rate of 3100 umol-g~(-1)-h~(-1) under visible light irradiation, accounting for an approximately 16 times higher than that of pristine graphite carbon nitride. Accordingly, as proposed strategy provides a new opportunity to explore advanced catalysts with superior properties for renewable energy utilization.
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