空位扩散诱导点缺陷环与富Cu相的相互作用

辐照诱导产生的点缺陷会加速核电站材料微观组织的演变,在很大程度上影响反应堆的寿命。本文基于相场法的四元连续相场模型,耦合了空位和间隙原子,利用该模型模拟了Fe-15at.%Cu-1at.%Ni-1at.%Mn合金在空位扩散机制下的相分离,研究了点缺陷与富Cu相的相互作用机理。结果表明,空位和间隙原子会促进富Cu相的长大和粗化,点缺陷初始浓度的升高会促进相分离,加快析出相的失稳分解速率,并且升高温度会延缓Cu原子和空位环的生长和粗化,点缺陷也可以增加一定的屈服强度,为探究空位扩散机制影响抗辐照材料性能方面提供了新的思路。     

Controlled vapor-pressure heat-treatment effect on deep levels in liquid-encapsulated czochralski-grown GaP crystals

Photocapacitance (PHCAP) measurements have been carried out on GaP crystals grown by the liquid-encapsulated Czochralski (LEC) method with heat treatment under various phosphorus-vapor pressures at different temperatures. Electron traps of E_C−1.1 eV, E_C−1.6 eV, E_C−1.9 eV, and a hole trap of E_V+2.26 eV are mainly detected. The phosphorus-vapor pressure dependence of the E_C−1.9 eV trap density and their diffusion behavior indicate that they are interstitial phosphorus atoms. The densities of both E_C−1.1 eV and E_C−1.6 eV traps are strongly dependent on the shallow impurity concentrations. Moreover, the density of E_C−1.1 eV traps increases with increasing phosphorus-vapor pressure. From these results, we suggest that E_C−1.1 eV traps are the complexes of shallow donors and antisite phosphorus atoms. Deep-level densities in GaP crystals after annealing at 860°C or 960°C for 60 min are decreased almost one order of magnitude lower than those in untreated substrate crystals, which should have occurred via out-diffusion of interstitial phosphorus atoms. However, such an effect is not prominent for 800°C treatment for 60 min.     

N~+和Bi~+离子注入InP反冲原子P和In深度分布偏离的研究

本文给出了用背散射和沟道技术所分析的N~+和Bi~+注入InP中In和P原子位移的面密度分布。发现移位原子In和P面密度分布峰的深度随注入剂量的增大而加深。在相同的剂量下磷原子分布峰与表面的距离比In原子峰的大。从移位原子面密度分布峰的移动和分布的展宽与注入剂量的关系出发,研究了离子注入过程中所存在的反冲效应。并讨论了移位原子的反冲机理。     

Estimating Bounds on Collisional Relaxation Rates of Spin-Polarized 87Rb Atoms at Ultracold Temperatures

We present quantum scattering calculations for the collisional relaxation rate coefficient of spin-polarized ⁸⁷Rb(f = 2,m = 2) atoms, which determines the loss rate of cold Rb atoms from a magnetic trap. Unlike the lighter alkali atoms, spin-polarized ⁸⁷Rb atoms can undergo dipolar relaxation due to both the normal spin-spin dipole interaction and a second-order spin-orbit interaction with distant electronic states of the dimer. We present ab initio calculations for the second-order spin-orbit terms for both Rb₂ and Cs₂. The corrections lead to a reduction in the relaxation rate for ⁸⁷Rb. Our primary concern is to analyze the sensitivity of the ⁸⁷Rb trap loss to the uncertainties in the ground state molecular potentials. Since the scattering length for the a³Σ⁺_u state is already known, the major uncertainties are associated with the X¹Σ⁺_g potential. After testing the effect of systematically modifying the short-range form of the molecular potentials over a reasonable range, and introducing our best estimate of the second-order spin-orbit interaction, we estimate that in the low temperature limit the rate coefficient for loss of Rb atoms from the f = 2,m = 2 state is between 0.4 × 10⁻¹⁵ cm³/s and 2.4 × 10⁻¹⁵ cm³/s (where this number counts two atoms lost per collision). In a pure condensate the rate coefficient would be reduced by 1/2.     

卤素原子在化学气相淀积金刚石薄膜过程中的作用

根据非平衡热力学耦合模型计算得到了碳氢氟和碳氢氯体低压金刚石生长的非平衡定态相图，计算与大量实验事实符合良好。     

30CrMnSiA钢渗扩氮高温淬火及渗扩氮亚温淬火研究

研究了预渗氮、渗扩氮高温淬火及平衡态原始组织渗扩氮亚温淬火、低温回火对结构钢３０ＣｒＭｎＳｉＡ的显微组织和显微硬度分布曲线的影响规律，观察了高氮区和低氮区的含氮马氏体形态和亚结构。     

Research in creating a fountain type frequency standard

Results of research aimed at creating a new generation of quantum frequency standards, i.e., a cesium fountain, are presented. Measurement data for controlling and detecting cold atoms are analyzed. The possibility of cooling cesium atoms to a level of the order of 2 µK is demonstrated by experiment.Translated from Izmeritelnaya Tekhnika, No. 1, pp. 18–23, January, 2005.     

Electronic passivation of silicon surfaces by halogens

We report the electronic passivation of a silicon surface by iodine termination. The resulting surface recombination velocity on Si(100) is less than 1 cm/s which is better than that obtained in concentrated hydrofluoric acid (HF). We have produced a surface recombination velocity of 20 cm/s using bromine. We present a simple model for these phenomena of a surface coverage of Si-X where X is a monovalently bonded halogen atom. The effectiveness of the passivation by halogens is shown to be limited by the oxidation of halogens by dissolved oxygen in solution. We demonstrate the use of halogen:methanol solutions as an alternative to HF for the control of silicon surface chemistry.     

卤代烃的系统命名问题辨析

本文对有机化学中文教材中卤代烃系统命名法常见的错误进行了分析,通过对比中国化学会制定的80原则中有机物系统命名原则,确定了正确的命名方法：应该选择最长的碳链为主链并作为母体名称;应该遵循最低系列原则为取代基编号;化合物名称中烷基应该排列在卤原子之前。