Ag/Ni和Cu/Ni界面的分子动力学模拟

用分子动力学方法对金属界面在弯曲状态下的力学行为做了模拟计算．在自行设计的两种弯曲模型中，首先比较了Ａｇ／Ｎｉ在不形成界面、形成界面（错配比约为１５％）以及Ｃｕ／Ｎｉ形成界面（错配比约为３％）时在动态弯曲过程中的势能－应变曲线，应力－应变曲线，模量－应变曲线，通过比较得出的结论是：界面的存在影响很大，失配位错影响界面的性质，并且错配比不同界面的力学性质亦不相同．同时，对计算元胞的尺寸效应做了详细的讨论，给出了用于计算机模拟中比较适宜的计算元胞的尺寸．最后，利用圆弧弯曲模型将静态平移周期性边界条件应用于动态 关键词：     

NiFe/Mo多层膜界面的电子显微学研究

用高分辨电子显微学方法研究了Ni₈₀Fe₂₀/Mo磁性多层膜，结果表明：(1)多层膜的结晶状态，随Mo非磁性层厚度而变化.当Mo层厚度为0.7nm时，多层膜基本为非晶；当Mo层厚度大于1.6nm时，Mo层和NiFe层内分别结晶为体心立方和面心立方多晶，层内晶粒尺寸为2—6nm.(2)在Mo层厚度为1.6和2.1nm的多层膜中，NiFe层和Mo层之间存在两种取向关系：(110)_Mo∥(111)_NiFe,［111］_关键词：     

Co/GaAs(100)界面形成以及Co超薄膜磁性质的研究

利用同步辐射光电发射和铁磁共振(FMR)研究了Co/GaAs(100)界面形成以及Co超薄膜的磁性质.结果表明,在低覆盖度(约为0.2nm)下,Co吸附原子与衬底发生强烈的界面反应,在覆盖度为0.9nm时,形成稳定的界面.从衬底扩散出的Ga原子与Co覆盖层合金化,而部分As原子与Co原子发生反应,形成稳定的键合,这些反应产物都停留在界面处很窄的区域(0.3—0.4nm)内.另一部分As原子偏析在Co覆盖层表面.结合理论模型,详细地讨论了界面结构及Ga，As原子的深度分布.FMR结果表明,生长的Co超薄膜具 关键词：     

Fe/SnO2非晶多层膜的磁特性

研究了高频溅射制备的Fe/SnO₂非晶多层膜的磁特性.当SnO₂层厚度d_s固定为5nm时，样品的饱和磁化强度M_s随Fe层厚度d_m的减小而降低，这主要受样品的死层效应和维度效应的影响.另外，在d_m很小时，样品呈现准二维磁性.样品居里温度T_C随d_m的减小单调下降.样品矫顽力H_c随d_m的变化呈现 关键词：     

Ni/a-Si多层膜中固相非晶化反应过程

采用原位X射线衍射法定量地分析研究了多晶Ni/非晶Si成分调制膜中的固相反应非晶化过程.提出了非晶Ni-Si相在Ni/a-Si多层膜固相非晶化反应中的生长模型.并对Ni晶界上的非晶化现象给予热力学和动力学上的解释. 关键词：     

界面结构对Cu/Ni多层膜纳米压痕特性影响的分子动力学模拟

金属多层膜调制周期下降到纳米级时,其力学性质会发生显著改变. Cu-Ni晶格失配度约为2.7%,可以形成共格界面和半共格界面,实验中实现沿[111]方向生长的调制周期为几纳米且具有异孪晶界面结构的Cu/Ni多层膜,其力学性质发生显著改变.本文采用分子动力学方法对共格界面、共格孪晶界面、半共格界面、半共格孪晶界面等四种不同界面结构的Cu/Ni多层膜进行纳米压痕模拟,研究压痕过程中不同界面结构类型的形变演化规律以及位错与界面的相互作用,获取Cu/Ni多层膜不同界面结构对其力学性能的影响特征.计算结果表明,不同界面结构的样品在不同压痕深度时表现出的强化或软化作用机理不同,软化机制主要是由于形成了平行于界面的分位错以及孪晶界面的迁移,强化机制主要是由于界面对位错的限定作用以及失配位错网状结构与孪晶界面迁移时所形成的弓形位错之间的相互作用.     

真空退火对周期性界面掺杂Ni80Co20薄膜磁性的影响

用磁控溅射方法制备了两个具有不同Fe层厚度的[Ni80Co20(L)/Fe(tFe)]N多层膜系列样品,其中tFe=0.1和2nm.研究了两个系列样品的磁及输运性质随Ni80Co20层厚度L的变化关系.在退火态[Ni80Co20(L)/Fe(0.1nm)]N系列样品中,发现各向异性磁电阻(AMR)和横向磁电阻(TMR)在L为10nm附近存在一较宽的增强峰,其峰位与制备态[Ni80Co20(L)/Fe(2nm)]25多层膜TMR的增强峰位一致.当L小于Ni80Co20合金的电子平均自由程时,制备态[Ni80Co20(L)/Fe(0.1nm)]N样品的各向异性磁电阻(Δρ)和零场电阻率ρ都随L的减小而增加,且ρ的增量超过Δρ的增量.ρ随L的依赖关系可采用Fuchs-Sondheimer理论描述.在L小于10nm时,制备态界面掺杂[Ni80Co20(L)/Fe(0.1nm)]N系列样品的矫顽力Hc随L近似直线上升,在L大于10nm后趋于饱和.退火后Hc显著下降.实验结果表明,在多层膜结构中,界面散射可导致ρ和Δρ的增强;磁性合金界面层还可导致畴结构的改变及TMR和AMR的增强.     

Fe/Si多层膜的层间耦合与界面扩散

对以本征Si及重掺杂ｐ型和ｎ型Si作为中间层的Fe/Si多层膜的层间耦合进行研究，并通过退火，增大Fe，Si之间的扩散，分析界面扩散对层间耦合的影响. 实验结果表明，层状结构良好的制备态的多层膜，Fe，Si之间也存在一定程度的扩散，它是影响层间耦合的 主要因素，远远超过了半导体意义上的重掺杂，使不同种类的Si作为中间层的层间耦合基本 一致.进一步还发现，在一定范围内增大Fe，Si之间的扩散，即使多层膜的层状结构已经有了相当的退化，Fe/Si多层膜的反铁磁耦合强度基本保持不变. 关键词： Fe/Si多层膜 层间耦合 界面扩散     

Pt1-xCux/Co多层膜的结构和磁性

系统地研究了Pt_1-xCu_x/Co多层膜的结构与磁性.除了特定的x=0.10—0.15区间外，在Cu浓度区间x=0.04—0.30内，随着中介Pt层内Cu浓度的增加，导致各向异性K_u和剩余磁化强度M_r⊥的单调下降.这可能是由于Cu原子在Pt层中的无序造成的，使Pt的晶面场对称性发生局域畸变，从而引起上述参数的下降.在特定区域内，可能是形成了PtCu合金的有序相，此时晶场对Co原子的作用就像只有Pt原子一样.这是Cu掺入 关键词：     

Mo/Si软X射线多层膜的界面粗糙度研究

用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo/Si多层膜系列, 利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo/Si多层膜的新鲜表面近似等同于同一多层膜的内界面,通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加,Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小,多层膜的峰值反射率先增加后减小。     

Morphological control of Ni/NiO core/shell nanoparticles and production of hollow NiO nanostructures

Chemical synthesis coupled with a microwave irradiation process allowed for the control of size (6–40 nm), shape, and shell thickness of Ni/NiO core/shell nanoparticles. In this unique synthetic route, the size of Ni nanoparticles (NiNPs) was strongly influenced by the nickel salt-to-stabilizer ratio and the amount of the stabilizer. Interestingly, it was observed that the shape of the nanoparticles was altered by varying the reaction time, where longer reaction times resulted in annealing effects and rupture of the stabilizer micelle leading to distinct shapes of Ni/NiO core/shell nanostructures. Product cooling rate was another important parameter identified in this study that not only affected the shape, but also the crystal structure of the core/shell nanoparticles. In addition, a simple and cost-effective method of microwave irradiation of NiNPs led to the formation of distinctly shaped hollow NiO nanoparticles. These high surface area core/shell nanoparticles with well-controlled morphologies are important and can lead to significant advancement in the design of improved fuel cells, electrochromic display devices, and catalysis systems.     

镍单晶膜上氧化镍的配位生长取向关系

对在膜面为(110),(001)和(111)的镍单晶膜上生成的氧化镍取向进行了电子衍射分析,除在(111)和(001)镍膜上肯定了前人已发现的氧化镍与镍的平行取向关系外,还在(110)和(001)镍单晶膜上发现了(111)_NiO∥(001)_Ni,〈110〉_NiO∥〈110〉_Ni取向关系以及〈110〉_NiO∥〈110〉_Ni氧化镍纤维织构。在所有氧化镍与镍的取向关系中均有〈110     

单畴Ni球观测及NicoreNiOshell的铁磁/反铁磁耦合研究

 使用微波辅助聚合方法制备了单分散单畴Ni纳米球，由MFM发现，尺度分布在100～180 nm的Ni球的一个相关特征是条型磁畴结构。用XRD、TEM、XPS以及EDAX测量了由Ni球进一步制备的Ni_coreNiO_shell高度球型纳米结构。用VSM 和SQUID进一步讨论了其铁磁/反铁磁界面耦合效应，估算了交换耦合场与粒子尺寸的关系。     

Exchange bias and training effect in Ni/Ag-doped NiO bilayers

A series of polycrystalline Ag-doped Ni_1−xAg_xO/Ni bilayers with x up to 0.2 were prepared by magnetron sputtering. X-ray diffraction, atomic force microscopy and transmission electron microscopy analyses reveal that Ag doping significantly reduces the mean NiO grain size and leads to the appearance of Ag nanoparticles on the surface of the Ag-doped NiO films. As x increases, the exchange bias field and coercivity at room temperature decrease as a consequence of the reduced thermal stability of smaller NiO grains and the screening effect resulting from the interfacial Ag nanoparticles. At lower temperatures, a slight enhancement of the exchange bias field is observed in the Ag-doped sample, indicating that the Ag doping increases the uncompensated NiO spin density. In addition, our studies find that the training effect of the Ag-doped sample can be well described by a spin configurational relaxation model, regardless of the presence of Ag nanopartiles at the interface.     

Perpendicular interlayer coupling in Ni80Fe20/NiO/Co trilayers

An in-plane perpendicular magnetic coupling between Ni80Fe20 and Co has been found in NiFe/NiO/Co trilayers for a NiO thickness ranging from 4 to 25 nm by magneto-optical Kerr effect and x-ray magnetic circular dichroism measurements. In the easy magnetization direction of the Co layer, the Co coercive field H(C) increases when the thickness of the NiO layer t(NiO) increases. Because of the coupling, H(C) is always larger than for NiO/Co bilayers with the same thicknesses. The saturation field of the NiFe layer H(S) decreases when t(NiO) increases, indicating a weakening of the coupling. Numerical simulations show that the presence of interface roughness combined with a small value of the NiO anisotropy can explain the observed 90 degrees coupling.     

Nanogravel structured NiO/Ni foam as electrode for high-performance lithium-ion batteries

Nanogravel structured NiO/Ni electrodes were fabricated by using two-step thermal oxidation method of commercial nickel (Ni) foam in air for lithium-ion batteries (LIBs). The macro- and micro-structures of the NiO/Ni foam were characterized using X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), and Raman spectroscopy. Galvanostatic tests revealed that the electrode exhibits no obvious capacity fading over 40 cycles at 1 C (718 mAg^?1) and 2.5 C (1.8 Ag^?1) current rate. The discharge capacity was higher than the theoretical capacity of NiO even at a high-current rate of 2.5 C. The electrodes can deliver a reversible capacity of 1116.65 mAh g^?1 after 20th cycle at 1 C rate and 1026.20 mAh g^?1 after 40th cycle at 2.5 C rate. The cyclic voltammograms and impedance spectra analysis indicated that a redox reaction of NiO–Ni⁰ with formation and decomposition of Li₂O. The excellent electrochemical performance is mainly attributed to the nanogravel structure of the NiO/Ni foam electrodes as well as its excellent electrical contact between NiO and Ni. The unique nanostructured NiO on the highly conductive metallic Ni in core resulted in the enhanced discharge capacity, coulombic efficiency, cyclic stability, and rate capability when utilized as negative electrodes in LIBs.     

NiO/Ni纳米线阵列紫外光电探测器的设计

设计了一种基于MSP430的NiO/Ni纳米线阵列紫外光电探测器。选用MSP430F149单片机作为主控芯片,液晶显示器作为输出端口,具有高光电探测灵敏性的新材料NiO/Ni纳米线阵列为探头,制作了信号采集、信号处理转换以及显示于一体的NiO/Ni纳米线阵列紫外光电探测器。本文NiO/Ni光电探测器以实用、可靠为目的,为研制更完善的光电探测系统奠定良好的基础。     

STUDY OF THE Al/GRAPHITE INTERFACE

Thin Al films with a thickness of 20－30nm were prepared by ultra-high vacuum deposition of Al onto a graphite surface parallel to a (0001) basal plane. The samples were annealed up to 1070K. X-ray photoelectron spectroscopy analysis has shown that for temperatures just higher than 770K, a little carbide occurs in the Al film and only an Al－C phase is present at the Al/graphite interface. After annealing at 970K, the Al₄C₃ phase can be observed, and the binding energy of the Al2p electrons increases continuously from 72.7 to 74.2eV with increasing temperature up to 1070K. Auger electron spectroscopy depth profiles are measured to investigate the phases existing in the Al film as well as at the Al/graphite interface. It is found that the Al₄C₃ phase at the interface is the final product of a series of Al carbides from the interfacial reaction between Al and graphite.     

颗粒物质中静摩擦力与接触面形状有关

用实验方法研究了探测棒在颗粒物质中受到的最大静摩擦力与棒截面形状的关系.观测到圆棒受到的最大静摩擦力最大,方棒次之,扁棒最小.根据力的传递原理,分析棒形状对颗粒物质内部力链传递的影响,计算结果与实验基本吻合.     

用可调探测深度电子能量损失谱与俄歇电子能谱研究Pb/Ni(001)界面

本工作用可调探测深度电子能量损失谱(ELS)与俄歇电子能谱(AES)研究Pb在Ni(001)表面的生长过程。发现Pb是一层一层地在表面生长的,即按Franck-van der Merwe(F-M)模式生长。当Pb的覆盖度大于1单层(ML)时,Pb的6s能带对应的电子能量损失峰开始出现,当Pb的覆盖度为3ML时,Pb的体等离激元的损失峰已相当明显。在Pb的蒸镀过程及随后的整个退火过程中,Pb的体等离激元峰,6s能带峰和Ni的3p能带峰的峰位与峰宽均保持与纯金属相同的值,也没有出现新的体等离激元峰。由此说明P