ChemInform Abstract: Electronic Structure,Elastic Anisotropy,Thermal Conductivity and Optical Properties of Calcium Apatite Ca5(PO4)3X (X: F,Cl or Br).

The structural properties, phase stability, electronic structure, elastic properties, and optical properties of Ca₅(PO₃)₄F (FA), Ca₅(PO₃)₄Cl (ClA) and Ca₅(PO₃)₄Br (BrA) are studied by DFT calculations with the generalized gradient approximation.     

大尺寸物光波面彩色数字全息高质量重建研究

为解决检测面尺寸较大时CCD难以得到高质量数字全息图的问题,本文利用负透镜设计光学系统让CCD接收来自物体的缩小虚像,以球面波为参考波,使用单色CCD近距离得到三种色光照射下的大尺寸彩色物体的数字全息图,然后采用可控放大率波面重建算法得到同一尺寸的数字全息重建像,合成彩色数字全息重建像.同时,使用两种消零级方法去除零级干扰,提高重建像质量,一种方法利用空间光调制器相移技术在参考光中加入一次任意相移,记录两幅数字全息图,消除重建零级像|另一种方法使用“无干扰全息图”消除重建零级像及共轭像.本文讨论结果可为大物体彩色数字全息及多波长数字全息检测应用提供有益的参考.     

像面滤波技术在无透镜傅里叶变换数字全息中的应用

无透镜傅里叶变换数字全息波前重建主要采用全息图的一次快速傅里叶变换方法,重建图像不能充分占有重建平面.本文基于像平面滤波技术,提出对物体局部区域光波场进行放大重建并让重建图像布满重建平面的方法,给出具有精细结构物体的数字全息波前重建实例.此外,将数字全息光波场重建视为具有方形出射光瞳的光学系统的相干光成像过程,导出了物体放大图像的分辨率与光学系统相关参量的关系,并通过实验给予证明.     

Interfacial electronic structure and magnetoelectric effect in M/BaTiO3 (M=Ni,Fe) superlattices

Using first-principles density functional theory, we investigate the interfacial electronic structure and magnetoelectric effect in M/BaTiO₃ (M=Ni, Fe) superlattices, and find a novel type of interfacial magnetoelectric coupling mechanism in the Ni/BaTiO₃ interface. This magnetoelectric effect is determined by the change of magnetic moments on Ni atoms near the interface, instead of the induced moments on interfacial Ti atoms in Fe/BaTiO₃ system, which is also distinguished from the spin-polarized carriers screening mechanism. The underlying physics is the strong interface bonding and the pdσ-type magnetic interactions between Ni 3d and O 2p spins. Furthermore, there exists an extraordinary intralayer oscillation of magnetic moments within the Ni layers, which may be observed in experiments.     

离子束溅射Ge量子点的应变调制生长

采用离子束溅射技术制备了单层和双层Ge量子点, 通过原子力显微镜对比了不同Si隔离层厚度和不同掩埋量子点密度情况下表层量子点的尺寸和形貌差异, 系统研究了掩埋Ge量子点产生的应变对表层量子点的浸润层及形核的影响, 并用埋置应变模型对其进行解释. 实验结果表明, 覆盖Ge量子点的Si隔离层中分布着的应变场, 导致表层量子点浸润层厚度的降低, 从而增大点的体积; 应变强度随隔离层厚度的减小而增加, 造成表层量子点形状和尺寸的变化; 此外, 应变还调控了表层量子点的空间分布. 关键词： Ge量子点 埋层应变 离子束溅射     

磁场辅助激光熔覆制备Ni60CuMoW复合涂层

采用磁场辅助激光熔覆技术,在Q235钢表面制备了Ni60CuMoW复合涂层,借助SEM,EDS 和XRD 等表征手段对涂层进行了微观组织和物相分析,利用维氏硬度计测试了复合涂层截面的显微硬度分布,通过摩擦磨损实验和电化学测试系统研究了复合涂层的磨损性能和耐腐蚀性能。研究结果表明:涂层主要由-Ni,Cu）固溶体、硅化物和硼化物组成,Cr3Si晶粒细化且均匀致密;磁场辅助作用下,激光熔覆涂层平均显微硬度达到913HV0.5,为无磁场辅助涂层的1.5 倍,磨损失重仅为无磁场涂层的36%,自腐蚀电位上升了100 mV,腐蚀电流密度降低了70%,耐磨耐蚀性能得到了显著改善。     

三七中Cu、Pb和Cd含量的不确定度评定

采用电感耦合等离子体-原子发射光谱法测定三七中Cu、Pb和Cd,对影响测定结果的不确定度来源进行了分析,在此基础上评定了分析结果的不确定度。研究表明,样品的重复性和校准曲线的拟合是影响不确定度的主要原因。     

电感耦合等离子体-质谱法测定工业硅中的痕量硼和磷

建立电感耦合等离子体-质谱法(ICP-MS)测定工业硅中痕量B和P的分析方法.采用HF-HNO3混合酸处理样品,对仪器工作参数进行优化,以Rh为校正内标,有效克服了基体效应及多元素分子离子干扰.分析结果表明,方法的检出限为:B为2.0μg·L-1、P为8.5μg · L-1,B和P的加标回收率分别为:97.2％-103.6％、95.2 ％-102.8％,精密度分别为2.6％、3.5％.方法可准确、快速测定工业硅中痕量元素B和P.     

Irreversibility of a quantum walk induced by controllable decoherence employing random unitary operations

Quantum walk is different from random walk in reversibility and interference. Observation of the reduced re- versibility in a realistic quantum walk is of scientific interest in understanding the unique quantum behavior. We propose an idea to experimentally investigate the decoherence-induced irreversibility of quantum walks with trapped ions in phase space via the average fidelity decay. By introducing two controllable decoherence sources, i.e., the phase damping channel (i.e., dephasing) and the high temperature amplitude reservoir (i.e., dissipation), in the intervals between the steps of quantum walk, we find that the high temperature amplitude reservoir shows more detrimental effects than the phase damping channel on quantum walks. Our study also shows that the average fidelity decay works better than the position variance for characterizing the transition from quantum walks to random walk. Experimental feasibility to monitor the irreversibility is justified using currently available techniques.     

Negative refraction with low absorption using EIT in a four-level left-handed atomic system

We suggest a scheme for obtaining negative refraction with low absorption in a left-handed atomic system. Under the appropriate conditions, the atomic system displays negative refraction with negative permittivity and permeability (left-handedness) in a common frequency range, simultaneously. And the imaginary parts of permittivity and permeability show transparently propagate in the same frequency range. Finally, the negative refraction show low absorption due to the EIT effect, and the figure of merit demonstrated this in this resonant atomic system.