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.
Reda M. AbdelhameedMahmoud El-ShahatMahmoud A. Abd El-Ghaffar
14页
查看更多>>摘要：Metal-organic frameworks (MOFs) have shown a great potential for producing efficient and eco-friendly photocatalysts. Furthermore, phthalocyanines (PCs) are promising materials in photocatalytic reactions because of their unique adsorption and photosensitizing properties. Here, three phthalocyanines (Pcs) derivatives with Al~(3+) and Co~(2+) ions as the central metal were prepared to attach them to the MOFs matrix. The photocatalytic decay performance of methylene blue (MB) and methyl orange (MO) and their mixtures were investigated under visible light illumination. The photocatalyst NH_2-MIL-125, Al-PcCl@NH_2-MIL-125, CoPc@NH_2-MIL-125, and CoPcPA@NH_2-MIL-125 show 0.01, 0.012, 0.035, and 0.046 min~(-1) MB degradation rate, respectively, while, the degradation rates of MO were 0.021, 0.027, 0.052 and 0.082, respectively. Amazingly, the degradation rates of MB in presence of MO showed boosted photocatalytic decomposition with the degradation rate of 0.066, 0.069, 0.085, and 0.120 min~(-1), respectively. This study illustrates a high performance for utilizing porous MOF-based materials not only as supports but as electron acceptors that enhance both photostability and photocatalytic activity.
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.
查看更多>>摘要：Nano-structured metallic oxides and carbon composites (NiO@C, Fe_3O_4@C and NiFe_3O_4@C) are successfully fabricated by the low-temperature calcinations of Ni/Fe precursors in an inert atmosphere. Density functional theory calculations show that atom rearrangements of NiFe_3O_4@C in unit cells are observed with respect to NiO@C and Fe_3O_4@C, leading to the altered exposed crystal planes and oxygen atoms redistributions on these exposed planes. Likewise, the metallic electron distributions are also changed within NiFe_2O_4@C due to bimetallic synergistic effects. In such fabricated scheme with the terephthalic acid template, the unique morphologies and structural characteristics of NiFe_2O_4@C are obtained with oxygen-rich exposed crystal planes, which are conductive to improving the conductivity, accommodating volume changes, providing rapid electron and Li ion transportations. Compared with NiO@C and Fe_3O_4@C, the fabricated NiFe_2O_4@C as lithium ion anodes can achieve the extremely high discharge capacity of 1808.8 mAh g~(-1) at 100 mA g~(-1) impressive reversible capacity of 1153.6 mAh g~(-1) after 200 cycles at 500 mA g~(-1) and average capacity of 647.1 mAh g~(-1) at 5000 mA g~(-1). The full battery is also assembled by NiFe_2O_4@C and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2 as anode and cathode, and shows a superior high specific energy of 432.0 Wh kg~(-1), which is far higher (1.5 times) than commercial full batteries.
查看更多>>摘要：Herein, porous Si_3N_4 ceramics embracing excellent mechanical and dielectric properties were achieved via gelcasting using N, N-dimethylacrylamide (DMAA) gel system while acting as pore-former. The increase of monomer content (8.0-23.0 wt%) led to an increase in porosity (39.53-43.60%) and pore connectivity, which accelerated vapor phase mass transport and promoted p-Si_3N_4 grain growth, thereby improving flexural strength (212.33-245.30 MPa) and fracture toughness (3.60-3.89 MPa-m~(1/2)). Attributable to the pores introduced by increasing monomer content, the e' and tanδ were significantly reduced with the values of 4.18-4.29 to 3.95-4.06 and 1.83-2.38 × 10~(-3) to 0.37-1.96 × 10~(-3), respectively, demonstrating excellent microwave-transparent properties. This work proved the great application potential of porous Si_3N_4 ceramics fabricated by gelcasting employing DMAA gel system in the field of microwave-transparent materials.
查看更多>>摘要：Single step hydrothermal method was used to synthesize molybdenum disulfide (MoS_2) thin films. The hexagonal structure of MoS_2 was confirmed by X-ray diffraction techniques (XRD). The nanosheets like morphology of MoS_2 films were confirmed using scanning electron microscopy (SEM). The optical band gap of pristine MoS_2 was found to be -1.53 eV. The prepared MoS_2 films were irradiated with ion and gamma radiation at different ion fluence and doses respectively. For ion irradiation, the samples were irradiated at ion fluences of 4.7 × 10~(16) ion/cm~2, 7.1 × 10~(16) ion/cm~2, 9.5 × 10~(16) ion/cm~2,11.9 × 10~(16) ion/cm~2 and 14.3 × 10~(16) ion/cm~2. In case of gamma irradiation, the samples were irradiated for 10 kGy, 100 kGy, 300 kGy, and 500 kGy and 800 kGy doses. The tensile strain induced in the sample was studied with the help of Raman spectroscopy and XRD technique. The defect induced tensile strain in MoS_2 films due to ion irradiation is higher as compared to gamma irradiation.
查看更多>>摘要：Y_(0.9)Gd_(0.1)Fe_2, which crystallize in a C15 cubic structure, can absorb up to 5 H/f.u. and its pressure-composition isotherm displays a multiplateau behavior related to the existence of several hydrides with different crystal structures. At room temperature Y_(0.9)Gd_(0.1)Fe_2H_x hydrides (2.9 ≤x ≤ 5) crystallize in three phases with cubic structure (C1, C2 and C3), two phases with monoclinic structures (Ml and M2), and one phase with orthorhombic structure (0), with the following sequence for increasing H concentration: C1, M1, C2, M2, C3, O. Each phase exists as single phase within a H homogeneity range, and they are separated from each other by two-phase domains. The reductions of crystal symmetry are related to various hydrogen orders into interstitial sites. Weak superstructure peaks were indexed by doubling the cubic cell parameter of the cubic C2 phase. Upon heating, the monoclinic Ml and M2 and the cubic C2 phases undergo order-disorder (O-D) transitions toward a disordered cubic structure C_(Dis). These O-D transitions are reversible with thermal hysteresis effects. The cubic C3 and orthorhombic 0 phases transform into a disordered cubic phase accompanied by H desorption.
查看更多>>摘要：BiCuSeO exhibits remarkable low thermal conductivity among oxides. The lone pair of the Bi~(3+) and the point defects brought about by elemental doping are thought to be the origin of the low thermal conductivity. In a recent study, however, the Cu atoms in BiCuSeO play a more significant role in reducing the lattice thermal conductivity than the above two factors. In this work, two series of polycrystalline Bi_(1-x)Ca_xCu_(0.975)SeO (x = 0.025,0.050,0.075,0.100, 0.125,0.150) and Bi_(0.95)Ca_(0.05)Cu_(1-y)SeO (y = 0.015,0.025, 0.035) are synthesized by solid-state reaction. All the materials are of single phase. Point defects introduced by partial elemental substitution and atom vacancy are expected to reduce the lattice thermal conductivity, however, which is not followed by the prediction for Bi_(1-x)Ca_xCu_(0.975)SeO with 0.050 ≤ x ≤0.125 and Bi_(0.95)Ca_(0.05)Cu_(1-y) with y = 0.015,0.025, and 0.035 in the temperature range where the resistivity decreases while the thermopower increases with temperature. This is in sharp contrast with those BiCuSeO with partial elemental substitution or Cu deficiency exhibiting either both the electrical resistivity and thermopower increase or decrease with increasing temperature. Our results support that the Cu atoms in BiCuSeO play a more significant role in reducing the lattice thermal conductivity than the lone pair of the Bi~(3+) and the point defects brought about by elemental doping.
NSTL
Elsevier