电场中LiF分子吸附H_2的理论研究

采用密度泛函理论方法研究了电场中H_2在LiF分子上的吸附行为.结果表明,无电场时,H_2能在Li与F原子上形成弱的物理吸附.外加电场可显著提高其吸附强度, H_2在Li/F上的吸附能由无电场时的-0.112/-0.122eV提高到场强为0.005 a. u.时的-0.122/-0.171 eV, H_2吸附在F上时更稳定.利用分子中的原子量子理论(QTAIM)方法研究了电场增强吸附的机理,表明电场促进了H_2与LiF间的电荷转移,同时使LiF及H_2极化,增强了其间的静电作用,从而提高了吸附强度.电场中LiF最多能吸附10个H_2,相应的质量密度达43.5 wt%.表明电场诱导LiF材料吸附H_2是一种具有潜力的储氢方法.     

非晶态Fe40Ni38Mo4B18（2826MB）合金粉末的高压压结与磁性研究

 本文研究了非晶态软磁材料Fe₄₀Ni₃₈Mo₄B₁₈（2826MB）合金粉末在高压下加温压结成三维大尺寸产品的可行性，并通过压结样品的复数导磁率在弱交变磁场中的行为，探讨了压结条件对压结样品的软磁性能的影响。结果表明，在本实验所采用的压力范围内，压结温度对压结样品的性能的影响大于压结压力的影响。     

A NEW CRITERION OF COMBINED TYPE CRACK—THE CRITERION OF MINIMUM DISTANCE(r_(min))IN PLASTIC REGION

The existence of the plastic area around the crack tip is an important factor against thecracking.In this plastic region.the cracking most likely develops in such a direction alongwhich the distance from the existant crack tip to the plastic region edge is the shortest one.Substituting the stress components at the crack tip for a combined cracking into R.Von.Mises equation of yielding condition,the boundary equation of the plastic regionaround the crack tip can be expressed as:where r is the distance from the crack tip to the boundary of plastic region.The direction inwhich the cracking develops can be determined by following conditions:One form of the material failures is the slipping under the action of shear stress.Underthe conditions of complex stress,the octahedral shear stress on a point around the crack tipis here.B devotes the.factor of the octahedral shear stress,which relates to the size. pattern ofcrack and the exerted stress.Its magnitude reflects the strength of the stress field aroundthe c     

Spin flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

A model ferromagnetic metal is used to calculate the spin-polarization which occurs during inelastic electron-metal scattering with the production of an electron-hole pair. The polarization is found to have contributions from unequal spin-flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modelling iron.     

Electrospun cerium nitrate/polymer composite fibres: synthesis, characterization and fibre-division model

Cerium (Ⅲ) nitrate/poly(vinylpyrrolidone) (Ce(NO3)3/PVP) composite fibres have been prepared by electrospinning. After calcining the composite fibres in air at 500℃,CeO2 nanowires were obtained. The characterizations of the as-spun composite fibres and resultant nanowires have been carried out by a scanning electron microscope (SEM),an infrared spectrometer,an x-ray diffractometer and a fluorescence spectrophotometer. Interestingly,some unusual ribbon-like or twin fibres were observed besides the common fibres with circular or elliptic cross sections. We developed a fibre-division model resulting from Coulomb repulsion and solvent vaporization to interpret the formation of the ribbons or twin fibres,which has been confirmed by the SEM studies. Our results also indicate that the formation of the ribbons or twin fibres is less dependent on operation voltage and work distance.     

COMPACT COUPLED LINEAR TAPERED LINE BANDPASS FILTER WITH TWO TRANSMISSION ZEROS

A new compact bandpass filter composed of two coupled linear tapered line resonators (LTLRs) is designed. The two resonators are arranged in different layers. The filter has two transmission zeros on both sides of the passband. It has small size and steep response below its passband. It is also shown that this filter has 0.6 dB low insertion loss at the centre frequency and 10.5% 3dB bandwidth. This work was supported by the Development Foundation of Shanghai Educational Committee (217608) and Shanghai Leading Academic Discipline Project (T0102).     

Entangling Two Multi-atomic Clusters Through a Cavity Field

Two atomic clusters, which have NA and Ns two-level atoms, respectively, are placed in a cavity but separated spatially. There is no direct interaction between the atoms. All the atoms interact with a single-mode of the cavity field. Quantum entanglement between the two atomic clusters is investigated for various initial states of the two atomic clusters and the field. When the cavity field is initially in a Fock state, we find that the time evolution of entanglement quasi-periodically oscillates regardless of the initial states of atoms. The oscillation period increases as the initial photon number increases. When all the atoms in both of the atomic clusters are initially in the excited state, we show that there is no entanglement between the atomic clusters with NA = NB = 1 regardless the initial state of the cavity field. However, when either NA or NB is larger than one, we find that the entanglement always exists even for a strong thermal field. In cases with different initial states of the atomic clusters, we notice that the entanglement becomes stronger as number of the atoms increases. When all the atoms in both of the clusters in the ground state, we also find that the entanglement can be enhanced even by a thermal field. We also notice that a single qubit can be entangled with multi-atoms which are initially in the ground state by the cavity field initially being in vacuum, thermal, coherent, and squeezed states.     

掺入Ni元素的LiCoO2晶体光谱结构及电子顺磁共振g因子

在弱场图像下,利用Racah不可约张量算符方法得到了三角对称3d4/3d6电子组态的210阶可完全对角化的微扰哈密顿矩阵、最近邻点电荷模型晶体结构常量公式和电子顺磁共振g因子公式.研究了LiCoO2晶体和掺入Ni的LiCoO2:Ni晶体中Co3+的基态能级、晶体结构和电子顺磁共振g因子.考虑了LiCoO2晶体和LiCoO2:Ni晶体中自旋单重态和三重态对Co3+基态能级的影响,讨论了LiCoO2晶体和在LiCoO2晶体中掺杂Ni后Co3+局域结构常量大小的变化是引起Co3+的基态能级变化的主要原因,理论和实验都证实了这一点.还计算了掺杂前后的电子顺磁共振g因子,计算结果与实验值符合得较好.     

High-Power Diode-End-Pumped Slab Composite Tm:YLF Compact Laser

We design a continuous-wave Tm:YLF laser with a composite slab crystal end-pumped by two fiber-coupled laser diodes at room temperature. We achieve a maximum continuous wave output power of 105 W for the bonded slab Tm:YLF laser; the corresponding slope efficiency is 47.7% and the optical-to-optical conversion efficiency is 42.0% with respect to the incident pump power. The laser operated at 1,907.5 nm with a beam quality factor of M² ～3.2 at the highest output power.