The valence electronic states at the model tunneling junction interface MgO∕Fe(001) system were systematically studied by comparing the spin-resolved photoemission spectroscopy of clean Fe(001) and MgO covered MgO∕F...
The valence electronic states at the model tunneling junction interface MgO∕Fe(001) system were systematically studied by comparing the spin-resolved photoemission spectroscopy of clean Fe(001) and MgO covered MgO∕Fe(001) surfaces using linearly p-polarized light. For the clean Fe(001) film on GaAs(001), five distinct features including bulk and surface-related transitions are found. The bulk and surface-state transitions are well-accounted for by the direct transition model based on the calculated energy band structure of bcc bulk Fe(001). The previously observed minority feature at a binding energy EB=−1.3eV is reinterpreted as a surface roughness associated transition. Upon the MgO adsorption on Fe(001), the surface-state transitions at EB=−0.3eV below Fermi energy EF appearing in both the majority and minority spin spectra at low photon energy (18eV to 35eV) were quenched. This is also the first direct experimental evidence of a minority spin surface state located just below the Fermi energy as predicted previously. The bulk states at the MgO∕Fe(001) interface exhibit a layer-dependent modification, i.e., the bulk states in the deeper Fe layer(s) remain unaffected, while the states of Δ5↓ band symmetry in the Fe layer(s) closest to the MgO∕Fe(001) interface are strongly modified, in contrast to the states of Δ1↑ symmetry. As a consequence of this interface effect, the “partial spin polarization” at the Fermi level changes sign from negative to positive values as seen in the spin asymmetry spectra at photon energies of 40eV and 60eV. The origin of this spin- and symmetry-dependent modification observed at MgO∕Fe(001) interfaces is discussed.
Nano-scale 8mol% titania doped yttria stabilized zirconia (8TiYSZ) powders were prepared by coprecipitation combined with azeotropic distillation process. Powder X-ray diffraction, BET method and TEM were performed to...
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Nano-scale 8mol% titania doped yttria stabilized zirconia (8TiYSZ) powders were prepared by coprecipitation combined with azeotropic distillation process. Powder X-ray diffraction, BET method and TEM were performed to characterize the powder properties. The relative density of 8TiYSZ sample sintered by spark plasma sintering technique at 1150°C for 3min reached 99%. The electrical conductivity of sintered pellet was much higher than the reported one.
The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation （DFT-DVM） method. After adding Si into Ti2A...
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The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation （DFT-DVM） method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state （DOS） shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SiAl1-xC has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al 3/7.
Based on the theory of photonic crystal and its characteristic, which was known as photonic band gap (PBG), the finite-difference time-domain (FDTD) method, including absorbing boundary condition and periodic boundary...
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Based on the theory of photonic crystal and its characteristic, which was known as photonic band gap (PBG), the finite-difference time-domain (FDTD) method, including absorbing boundary condition and periodic boundary condition, was used to simulate transmission characteristic of two-dimensional photonic crystal, which has periodic Al2O3 cylinder array structure. Incident wave was presumed as s-polarized wave. In two incident angles which were 0° and 30°, electric field, phase and transmissivity in the range of 1-30 μm were calculated. Numerical simulation results showed that PBG of photonic crystal existed in the range 12-18 μm (infrared waveband), and it may be used to develop infrared wave-guide.
A series of zirconia porous ceramics with different density are fabricated with commercial zirconia powder and zirconia hollow balls by pressureless sintering technology. The microstructure and phase transformation ar...
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A series of zirconia porous ceramics with different density are fabricated with commercial zirconia powder and zirconia hollow balls by pressureless sintering technology. The microstructure and phase transformation are characterized respectively by SEM and XRD testing methods. The result indicates that the density and compressive strength depend greatly on zirconia powder content at the same sintering temperature, and elevating sintering temperature just has a little effect on the density and compressive strength for the samples of the same zirconia powder content. The XRD diffraction patterns analysis shows that elevating sintering temperature is helpful to eliminate monoclinic zirconia and the best sintering temperature should be beyond 1700°C.
Direct liquid fuel cells have attracted intensive research because of the promised application in portable fuel cell systems. Liquid fuel such as formic acid crossover through the proton exchange membranes (PEMs, e.g....
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The effect of the fabrication methods of the conventional hot-pressed membrane-electrode assembly (hot-pressed MEA) and catalyst-coated membrane (CCM) on the utilization efficiency of Pt electrocatalysts, methanol cro...
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The novel sandwich composites were prepared by sandwiching a polyvinylidene fluoride/Tb- Dy-Fe alloy composite （PVDF/Terfenol-D） between polyvinylidene fluoride/lead zirconate titanate composites （PVDF/PZT）. The m...
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The novel sandwich composites were prepared by sandwiching a polyvinylidene fluoride/Tb- Dy-Fe alloy composite （PVDF/Terfenol-D） between polyvinylidene fluoride/lead zirconate titanate composites （PVDF/PZT）. The maximum magnetoelectric effect voltage coefficient, （dE/dn）33max, of the sandwich composites is higher than that of three-phase composites at their own optimal loading level of Terfenol-D. This is attributed to less interface relaxations of strain and better polarization of the sandwich composites. When the volume fraction of Terfenol-D is higher than 0.10, no coupling interaction for three-phase composites could be observed, but （dE/dn）33max of sandwiched composites still reached 20 mV/（***）. At high magnetic field intensity, the magnetoelectric effect voltage coefficient, （dE/dn）33, of sandwich composites is higher than that of three-phase composites; at low magnetic field intensity, （dE/dn）33 of sandwich composites is lower than that of three-phase composites. At their resonance frequency, the （dE/dn）33max of the sandwich composites and the three phase composites are 150 mV/（***） and 42 mV/（cmoOe）, respectively. This significant increase of （dE/ dn）33max at resonance frequency confirms the improvement of maximum magnetoelectric effect coefficient via sandwich-structured composites.
Protein adsorption behavior on the surfaces of biomedical materials is highly related to the biocom- patibility of the materials. In the past, numerous research reports were mainly focused on the effect of chemical co...
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Protein adsorption behavior on the surfaces of biomedical materials is highly related to the biocom- patibility of the materials. In the past, numerous research reports were mainly focused on the effect of chemical components of a material’s surface on protein adsorption. The effect of surface topography on protein adsorption, the topic of this review, has recently received keen interest. The influence of surface nano-topographic factors, including roughness, curvature and geometry, on protein adsorption as well as the protein adsorption behavior, such as the amount of protein adsorbed, the activity and morphology of adsorbed protein, is introduced.
CoSb3 with nanoscale was synthesized by Cross-coprecipitation. A precursor consisting of antimony oxide and cobalt hydrate was prepared by the reaction of CoCl2, SbCl3 and both precipitators at room temperature. The p...
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CoSb3 with nanoscale was synthesized by Cross-coprecipitation. A precursor consisting of antimony oxide and cobalt hydrate was prepared by the reaction of CoCl2, SbCl3 and both precipitators at room temperature. The precursor was reduced in thermal treatment under hydrogen atmosphere whereby the CoSb3 was thus obtained. The parameters especially reducing temperature and atmosphere (content of H2) influence the constituent phases and particle size of product significantly. The single phase CoSb3 with the average grain size of 60-70 nm was obtained after reduced at 723 K for 2 h with pure H2. Nanoscale CoSb3 powder was used as starting materials, and bulk CoSb 3 compound was prepared by spark plasma sintering (SPS). The effect of grains size on thermal conductivity was investigated.
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