Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection *** results showed that rutile ...
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Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection *** results showed that rutile titania formed at 70℃without calcination in *** rutile TiO_2 had good crystalline and small particle *** formation mechanism of rutile was also *** photocatalytic activity of the prepared particles was tested for the degradation of methyl *** photocatalytic activity of rutile TiO_2 was higher than those obtained from Degussa P-25 TiO_*** reasons for high photocatalytic activity of futile were discussed.
Amorphous ribbons of (Ni0.75Fe0.25)78-xNbxSi10B12（x=0,5） were prepared by a single roller melt-spinning technique in air atmosphere. The crystallization kinetics of the alloys were investigated by means of continuou...
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Amorphous ribbons of (Ni0.75Fe0.25)78-xNbxSi10B12（x=0,5） were prepared by a single roller melt-spinning technique in air atmosphere. The crystallization kinetics of the alloys were investigated by means of continuous heating,and the activation energies of the alloys were calculated using Kissinger plot method and Ozawa plot method on the basis of differential thermal analysis data. The crystallization products were analyzed by X-ray diffraction. After the (Ni0.75Fe0.25)78-xNbxSi10B12 amorphous alloy was annealed at the temperatures 715 and 745?K,a single phase of γ-（Fe,Ni） solid solution with grain sizes of about 10.3 and 18.5?nm,respectively,precipitates in the amorphous matrix. The crystallized phases are γ-（Fe,Ni） solid solution,Fe2Si,Ni2Si,and Fe3B after annealing at 765?K. The (Ni0.75Fe0.25)78-xNbxSi10B12 amorphous alloy was annealed at 720,750,and 800?K; and the crystallization phases,γ-（Fe,Ni） solid solution,（Fe,Ni） 23 B6,Ni 31 Si 12 and Nb2NiB 0.16 form simultaneously.
We report Fe-doped NiO nanopowder, exhibiting room ferromagnetism mainly arising from the double exchange mechanism through the doped Fe ions and free charge carriers. Electrical measurements reveal that ac conductivi...
We report Fe-doped NiO nanopowder, exhibiting room ferromagnetism mainly arising from the double exchange mechanism through the doped Fe ions and free charge carriers. Electrical measurements reveal that ac conductivity of the polycrystalline ceramics with Fe-doped NiO can be expressed as the sum of a frequency-independent conductivity σ1 and a frequency-dependent one σ2. The latter σ2 can be represented by the frequency dispersion for the dielectric loss due to the hopping diffusion of charge carriers with a single effective staying time τ∼6.11×10−10s at a lattice site.
Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion...
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Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion from Li-N-H to Mg-N-H is presented, two types of possible reaction mechanisms are discussed and three amide-synthesizing methods are introduced. The unsolved problems of development and application of the Metal-N-H system are also generalized.
The effect of heat treatment on the magnetostrictive properties of a (110)-oriented polycrystal Fe83Ga17 alloy was investigated. It was found that the saturation magnetostrictive strain of the quenched Fe83Ga17 alloy ...
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The effect of heat treatment on the magnetostrictive properties of a (110)-oriented polycrystal Fe83Ga17 alloy was investigated. It was found that the saturation magnetostrictive strain of the quenched Fe83Ga17 alloy exceeded 300 × 10 under a compressive stress of 25 MPa. The results of Neutron diffraction and differential thermal analysis confirmed that slow cooling leads to the change of phase structure which results in the change of magnetostrictive strain. The increase in magnetostrictive strain of the Fe83Ga17 alloy treated by quenching is explained as that the long-range DO3 is suppressed.
A new approach to produce superfine WC-Co powder by direct reduction and carbonization is proposed. Water-soluble salts containing W and Co were used as raw materials. Tungsten and cobalt oxide powder （CoWO4/WO3） wa...
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A new approach to produce superfine WC-Co powder by direct reduction and carbonization is proposed. Water-soluble salts containing W and Co were used as raw materials. Tungsten and cobalt oxide powder （CoWO4/WO3） was first formed by a spray-pyrolysis technique, which was then mixed with carbon black and converted to WC-Co composite powder at 950℃ for 4 h in N2 atmosphere. The resulting powder has a particle size of 100-300 nm.
Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the relative retention time （RRT） of polybrominated diphenyl ethers （PBDEs） were predic...
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Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the relative retention time （RRT） of polybrominated diphenyl ethers （PBDEs） were predicted. A four-variable regression model （M30） with the correlation coefficient of 0.9816 and the root mean square errors of 0.061 was developed using a training set including 30 PBDEs. The correlation coefficient of 0.9841 and the root mean square errors of 0.054 between the values of RRT predicted by M30 and the RRT observed for 16 external PBDEs show a good predictive potential of M30. The descriptors included in the M30 represent four interactions between four pairs of atom types, i.e., atom -C= and -C=, -C= and 〉C=, 〉C= and 〉C=, -C= and -Br.
A new organic-inorganic hybrid compound （dienHs）2（P2Mo5O23） （1） [dien=NH（CH2CH2NH2）2] has been hydrothermally synthesized and characterized by elemental analyses, IR spectrum, thermogravimetric analysis, and t...
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A new organic-inorganic hybrid compound （dienHs）2（P2Mo5O23） （1） [dien=NH（CH2CH2NH2）2] has been hydrothermally synthesized and characterized by elemental analyses, IR spectrum, thermogravimetric analysis, and the single crystal X-ray diffraction technique. Compound 1 crystallizes in the triclinic system with space group P1 and a=0.9790（2） nm, b=0.9922（2） nm, c= 1.4644（3） nm, α=95.510（10）°, β=98.860（10）°, γ=95.700（10）°, V=1.3895（5） nm^3, Z=2, R=0.0465. The results show that the compound consists of dienH3^3＋＋ and P2Mo5O23^6-, and the heteropoly anion P2Mo5O23^6- is connected to a 1-D chain structure with the protonated dien by hydrogen bonds.
The high-temperature mechanical properties were very important to structural materials, especially structural ceramics. Hence, the strength, elastic modulus, stress relaxation and creep behavior of the multilayer mate...
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The high-temperature mechanical properties were very important to structural materials, especially structural ceramics. Hence, the strength, elastic modulus, stress relaxation and creep behavior of the multilayer materials at elevated temperature were studied in this paper. According to the curves of mechanical properties varieties with temperature risen from room-temperature to 1300°C, the multilayer materials could remain relatively high mechanical properties until 1150°C. Otherwise, the creep function of the multilayer composites was also determined, in which the stress exponent was 1.4 and activation energy was 204kJ/mol. By contrasting to the monolithic ceramics of Al2O3 and Ti3SiC2, the main creep mechanisms include: interface diffusion creep (in Al 2O3 layers), dislocation movement creep, grain delamination and sliding (in Ti3SiC2 layers).
In order to improve water resistance of phosphors and the stability of particles in aqueous suspensions, the phosphor particles were coated with varying amounts of silica via the hydrolysis of tetraethyl orthosilicate...
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In order to improve water resistance of phosphors and the stability of particles in aqueous suspensions, the phosphor particles were coated with varying amounts of silica via the hydrolysis of tetraethyl orthosilicate. The composite particles were characterized by transmission electron spectroscopy, BET N2 gas adsorption, sedimentation time studies and fluorescent spectrometer. The specific surface area of the silica-coated phosphor particles showed a non-systematic increase. In comparison to the uncoated phosphor (3.65m2/g), silica coatings of 13, 25, 50, 75wt% yielded specific surface areas of 15.19, 14.29, 37.90 and 226.12 m2/g respectively. This behavior can be explained based on a heterocoagulation coating mechanism in which silica clusters adsorb onto the phosphor particles surface. The sedimentation data display the stability of the coated particles improved as the silica content increased. The excitation and emission spectra show that the luminescent properties of the phosphors are unimpaired or even better. The optimum luminescent properties obtained when coating 50wt% silica after calcining at 400°C.
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