Influence of Carbon-doped Content on Formation Conditions of Coesite

The mixtures of a-quartz and graphite powder with different mass ratios were, respectively, high-energetically mechanically milled and then treated under high pressure and high temperature. The influences of carbon content on the synthesis conditions of coesite were investigated. The experimental products were characterized by XRD, TEM, and Raman spectrometry. The results show that the existence of carbon can obviously inhibit the formation of coesite, and the higher the carbon content of the initial material, the higher the pressure for forming coesite.

Effective-Field Theory for Kinetic Ising Model on Honeycomb Lattice

作为一个分析方法，有效地的理论(水蜥) 被用来面对震荡的一条正弦曲线学习运动 Ising 模型的动态反应领域。平均磁化的运动的有效地的方程为蜂房格子被给(Z = 3 ) 。Liapunov 代表 λ 为讨论磁化的稳定性被计算，决定阶段边界被用来。在领域振幅 h 0/ZJ-temperature T/ZJ 飞机，分开的阶段边界动态订，混乱阶段被拉了。与预言了分开连续、不连续的转变的一根动态阶段边界线的一个 tricritical 点的以前的分析结果相对照，我们发现转变总是是连续的。在我们的结果和以前的分析结果之间有矛盾，因为他们不介绍足够地强壮的变化。

Fractal Nature of Capillary and Viscous Fingering in Two-Dimensional Porous Media

A computer model of capillary and viscous fingering in a porous media is presented,which treats the media as a square lattice connected with randomly chosen radius.The fractal properties of the model are studied for shell-shell aggregation method by Monte Carlo simulation.The simulation results show that the dimension D increases along with increasing of M and decreasing ofμ,where M andμare the ratios of the viscosity of the two fluids and the most probable radius of the throat in porous media respectively.It is found that there exist four regions for fluid.

Novel Phenomenon on Valence Unvariation of Doping Ion in Yb:YAG Transparent Ceramics Using MgO Additives

Yb：YAG nanopowders were synthesized by the alcohol-water co-precipitatlon method adding MgO as sintering additives. Appropriate amount of MgO adding can restrict the agglomeration and reduce the particle size of Yb：YAG powders. When the MgO content was 0.04wt%, well-dispersed Yb：YAG powders with ellipsoidal particles of less than 100 nm diameter were obtained. The experimental results showed the valence variation of doping ion Yb〉 would not appear when adding MgO as sintering additives, so ceramics showed colorless transparent instead of green due to Yb^2＋ color center using traditional SiO2 as additives. The transmission of the sintered Yb：YAG ceramics can reach 80.6% even without annealing. Ceramic morphology showed that the grains had uniform-distribution with the size of 10 iam or so, and no impurity and pore existed in the grain boundary and crystalline while using optimal sintering conditions.

Stark Effect Dependence on Hydrogenic Impurities in GaAs Parabolic Quantum-Well Wires

The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolicquantum-well wires(QWWs)subjected to external electric and magnetic Gelds are investigated using the finite-differencemethod within the quasi-one-dimensional effective potential model.We define an effective radius ρ_(eff)of a cylindricalQWW,which can describe the strength of the lateral confinement.For the ground state,the position of the largestprobability density of electron in x-y plane is located at a point,while for the lowest excited state,is located on acircularity whose radius is ρ_(eff).The point and circularity are pushed along the left half of the center axis of thequantum-well wire by the electric field dire ted along the right half.When an impurity is located at the point or withinthe circularity,the ground-state or lowest excited-state binding energies are the largest;when the impurity is apart fromthe point or circularity,the ground-state or lowest excited-state binding energies start to decrease.

Percolation Model of the Temperature Dependence of Exotic Magnetic Field in Doped Manganese Perovskites

我们调查磁性的转变在一(La1-xBx )(2/3 ) Ca1/3MnO3 系统，由顺磁、铁磁性的域组成，基于一个磁性的理论过滤模型。在吝啬地的近似，是的抵抗一，温度和磁场的功能被导出经分解并且数字地模仿了。当应用磁场不是太强壮的时，磁场上的临界溶液温度的依赖是线性的，这被发现。我们的理论断言在对最近的试验性的观察的好同意。

Preparation of YAG Powder by Co-Precipitation Method in a Narrow pH-Change Environment

YAG（Y3Al5O12） powder was prepared by co-precipitation method.To avoid pH values changing intensely during titration process,the 4 3 NH HCO solution with 4 3 NH NO was used as precipitant solution.The pH change of precipitant solution during titration process,compositions of precursor,phase formation process and morphology of the prepared powder were investigated by means of pH meter,FT-IR,XRD and TEM.The results show that the presence of 4 3 NH NO in 4 3 NH HCO solution is crucial to alleviate the pH change,lower the calcination temperature and meliorate the morphology of YAG powder.The mechanisms were studied in detail.The YAG phase can be obtained at a lower temperature of 900 ℃.The obtained powder,composed of elliptical particles,showed a meliorated morphology.

Preparation of Polycrystalline Singe-phase K0.3MoO3 by Hot Isostatic Pressing Sintering

Nearly single-phase and polycrystalline charge-density-wave compound K0.3MoO3 have been prepared by using a simple method. In this work, K2CO3 and MoOs were used as starting materials and reacted by hot isostatic pressing （HIP） sintering. The product is nearly single phase K0.3MoO3 determined by X-ray powder diffraction （XRD） and energy dispersive spectroscopy （EDS）. Measurement of temperature dependence of resistivity reveals that the transport property of polycrystalline K0.3MoO3 obviously differs from that of single crystal due to the grain boundaries and the anisotropic structure in this kind of compound.

Mean-Field Studies of a Mixed Spin-3/2 and Spin-2 and a Mixed Spin-3/2 and Spin-5/2 Ising System with Different Anisotropies

混合 spin-3/2 和混合 spin-3/2 和 spin-5/2 Ising 的磁性有不同 anisotropies 的铁磁性的系统借助于吝啬地的理论(MFT ) 被学习。单个离子的 anisotropy 力量上的阶段图的依赖也被学习。在混合 spin-3/2 和 spin-2 Ising 模型，除秒顺序阶段转变以外，第一顺序混乱阶段转变和 tricritical 线被发现。在混合 spin-3/2 和 spin-5/2 Ising 模型，没有一阶的转变和 tricritical 线。

Magnetic Properties of Transverse Ising Model under a Time Oscillating Longitudinal Field

一个横向的 Ising 旋转系统，面对时间依赖者纵的地，被有效地的理论(水蜥) 学习。平均磁化的运动的有效地的方程为简单立方的格子被给(Z = 6 ) 并且蜂房格子(Z = 3 ) 。Liapunov 代表为讨论磁化的稳定性被计算，决定阶段边界被用来。在 h0/ZJ /ZJ 飞机并且在 h0/ZJ T/ZJ 飞机的动态阶段转变图被拉了，并且动态阶段转变边界上没有动态 tricritical 点。在动态阶段边界之上的热变化的效果被讨论了。

Spin-Dependent Electron Properties of a Triple-Terminal Quantum Dot Structure

Electron transport properties of a triple-terminal Aharonov-Bohm interferometer are theoretically studied.By applying a Rashba spin-orbit coupling to a quantum dot locally, we find that remarkable spin polarization comesabout in the electron transport process with tuning the structure parameters, i.e., the magnetic flux or quantum dotlevels. When the quantum dot levels are aligned with the Fermi level, there only appear spin polarization in thisstructure by the presence of an appropriate magnetic flux. However, in absence of magnetic flux spin polarization andspin separation can be simultaneously realized with the adjustment of quantum dot levels, namely, an incident electronfrom one terminal can select a specific terminal to depart from the quantum dots according to its spin state.

Investigation of Fe-Ni-B and Fe-Cr-B Ultrafine Amorphous Alloy Powders Prepared by Chemical Reduction

Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffraction. The B concentrations for the two alloy systems did not change dramatically, as the preparation condition changed. An oxide film covered up the powders. The maximum magnetization decreased as increasing the content of Ni or Cr.

Effect of annealing on structural and optical properties of lead tungstate microcrystals

Shuttle-like lead tungstate （PbWOa） microcrystals are synthesized at room temperature using the precipitation method with the cetyltrimethyl ammonium bromide. Results from both the X-ray diffraction and the scanning electron microscopy show that the lattice distortions of the PbWO4 microcrystals are reduced significantly when the annealing temperature is increased to 873 K. The result from the ultraviolet-visible diffuse reflectance spectroscopy shows that the exciton absorption appears in the sample annealed at 673 K. The self-trapped exciton luminescence due to the Jahn- Teller effect is also observed in the blue band. The interstitial oxygen ions in the WO42- groups are mainly resposible for the enhancement effect of the green luminescence of the annealed samples. The above results are supported by the spectrum analysis of the as-grown and the post-annealed samples using the X-ray photoelectron spectroscopy.

The influence of nickel dopant on the microstructure and optical properties of SnO2 nano-powders

The microstructure and optical properties of Ni-doped SnO2 nano-powders are studied in detail. By Ni-doping, not only the grain size reduces, but also the grain shape changes from nano-rods to spherical particles. The crystallization becomes better with annealing temperature increasing. The band gap energy decreases as nickel doping level increases. The sp-d hybridization and alloying effect due to amorphous SnO2-x phase should be responsible for the band gap narrowing effect. Nickel dopant does not change the photoluminescence （PL） peak positions.

Scaling and Scaling-Relevant Dynamical Properties of Penrose Tiling

The scaling and the scaling-relevant spectral properties of Penrose tiling are investigated.The fractal dimension df of this tiling is analytically obtained,which is two,equal to its Euclidean dimension.Similar to usual self-similar structure,the vibrational density of states for Penrose lattice is also found to follow a power law p(ω)~ωds^(-1) with spectral dimension ds=2,which accounts for a special vibrational excitation in quasicrystals:the fracton-like excitation,whose state is critical.The simulation of random walk on this Penrose lattice indicates that the diffusive dimension d_(w)=2,thus the relation ds=2df/d_(w) holds.

Electroluminescence from Indium Tin Oxide Film/Nanoscale Si Oxide/p-Si Structure

After an Si oxide layer of 3nm thickness had been grown by using magnetron sputtering on a p-type Si(100)substrate,an indium tin oxide(ITO)film was deposited onto the Si oxide layer by using electron beam deposition.Electroluminescence(EL)from such an ITO/Si oxide/p-type Si structure was measured under a forward bias of 5V or more.Its EL power efficiency is about eight times as large as that of a semitransparent Au/Si oxide(3nm)/p-Si structure.The experimental results indicate that the greater EL power efficiency is due not only to the higher optical transparency of the ITO film compared with Au film in a range of 300 to 900nm,but also to some new luminescence centers introduced in the Si oxide layer during the ITO deposition process.

Quantum XY Spin Glass Model with Longitudinal Ferromagnetic Coupling

The quantum XY spin glass model with longitudinal ferromagnetic coupling is investigated in static replica symmetry limit.Several thermodynamic quantities are calculated numerically.We find that the ferromagnetic coupling enhances the stability of replica symmetric solution.A 2-dimensional Ising model like transition is found,which demonstrates that the ferromagnetic coupling increases the order of spin glass model.Affected by the ferromagnetic coupling,transverse component of the susceptibility has two cusps corresponding to transverse-longitudinal spin-glass phase transition and longitudinal spin glass-paramagnetic transition separately.

Computer Simulation of Radial Viscous Fingering in Two-Dimension Porous Media

A computer model of capillary and viscous fingering in a porous medium is presented which treats the medium as a square lattice connected with randomly chosen radius.The fractal properties of the model are studied for circular shell-shell aggregation by a Monte Carlo simulation.The simulation results show that the dimension D increases with decrease of the viscous ratio M and increase of the throat radius.It is found that the displacement process is stable when M=1,and viscous fingering pattern of porous media in the limit M→∞is similar to the diffusion-limited aggregation pattern in a uniform system.For larger viscous ratio M and smaller positive integer k,the fluid is situated in the co-existence region of viscous and capillary fingering.

Fractal Nature of Viscous Fingering in Random Sierpinski Carpet

The viscous fingering(VF)in a random Sierpinski carpet with bond radii of the truncated Rayleigh distribution has been investigated by means of successive over-relaxation techniques.A universal formulation of fractal dimension for VF in fractal space has been introduced.The topology and geometry of the porous media are found to have strong effects on displacement process.The fractal dimension D can be reasonably regarded as a useful parameter to evaluate the sweep efficiency and oil recovery.