C60单晶的表面形貌与生长缺陷

用气相法生长出了毫米尺寸的具有规则晶面和金属光泽的高质量的纯C₆₀单晶.X射线衍射分析表明,C₆₀单晶在室温下具有面心立方(fcc)结构,晶格常数为α=1.4199(4)nm。用扫描电子显微镜和光学显微镜观察了C₆₀单晶的形貌,除观察到fcc结构的晶体所特有的{111}和{200}两种稳定晶面以及非常容易形成的孪晶之外,还发现了在{111}面上的树枝状、垄状和生长丘以及在{200}面上的树枝状、游泳池状和生长丘的生长缺陷。对C_{60 关键词：}     

Rb掺杂C60单晶的相衍变和电子态

在C₆₀单晶超高真空解理面上制备C₆₀的Rb填隙化合物薄膜.用同步辐射光电子能谱研究了相衍变过程.观察到对应于固溶相、Rb₁C₆₀和Rb₃C₆₀的电子态密度分布.当数纳米厚Rb₃C₆₀薄膜在C₆₀单晶（111）解理面形成后，室温条件下进一步沉积Rb至样品表面不产生fcc到bct或bcc结构相变.C_{60 关键词： 4}C₆₀和Rb₅C₆₀吸附相')" href="#">金属性Rb₄C₆₀和Rb₅C₆₀吸附相 60单晶')" href="#">C₆₀单晶 相衍变 同步辐射光电子能谱     

GaAs(100)衬底上C60单晶膜的取向生长

利用双温区真空蒸发沉积技术成功地在GaAs（100）衬底上实现了完全（111）取向的C₆₀单晶膜的生长．用扫描电子显微镜和Ｘ射线衍射技术对C₆₀单晶膜的形貌和结构进行了分析．结果表明：能实现C₆₀取向生长的衬底温度范围很窄，温度过高或过低都易造成晶粒的取向无序．对实验结果做出了合理的解释，并讨论了C₆₀单晶膜的生长机制 关键词：     

Co100-xMnx合金在GaAs(001)表面的生长结构和磁性的实验研究

对Co_100-xMn_x合金在GaAs(001)表面的分子束外延生长、晶体结构和磁学性质进行了研究.结果表明,当0100-xMn_x合金薄膜是体材料中不存在的体心立方(bcc)结构,并且具有较强的铁磁性,当44100-xMn_x合金薄膜最初为bcc结构,随着厚度的增加,逐渐从bcc向面心立方(fcc)结构转化,最后成为完全的fcc结构,薄膜具有较 关键词：     

织构C60薄膜的生长与光致发光特性

用Hot Wal方法，在氟金云母单晶上生长出了（111）织构的C₆₀薄膜．用X射线衍射、Raman散射、扫描电子显微镜和原子力显微镜研究了织构C₆₀薄膜的结晶质量和结构特性．测量了织构C₆₀薄膜在室温300K和低温77K的光致发光光谱．对所得结果进行了分析与讨论 关键词：     

C60单晶生长及特性的研究

用气相生长法生长了最大线度约为１．５ｍｍ的C₆₀单晶。单晶Ｘ射线衍射分析结果表明，该C₆₀单晶为ｆｃｃ结构，晶格常数为１．４１３ｎｍ，在２５１Ｋ附近与相变有关的电导率的尖锐跳变表明，C₆₀单晶具有很高的纯度和良好的均匀性。观察到在２７４Ｋ附近激活能的变化，这可能是另一个相变的反映。 关键词：     

第一原理对铝的静态结构和相变的计算

 在密度泛函理论（DFT）和广义梯度近似（GGA）下,用缀加平面波加局域轨道（APW+lo）方法对铝的晶格常数、体弹模量以及在静态高压下的固态相变进行了计算。计算得出面心立方晶格结构（fcc）向六角密堆积结构（hcp）和体心立方结构（bcc）的相变分别发生在220 GPa和330 GPa,hcp向体心结构bcc的相变发生在380 GPa。计算结果和实验数据以及其它理论计算符合较好。     

一维应变加载下单晶铁结构转变的微观研究

采用嵌入原子势和分子动力学方法,模拟了单晶铁在一维应变条件下由体心立方（bcc）转变为六角密排（hcp）结构的微观过程. 当应变加载至相变临界值时,hcp相开始均匀形核并沿{011}晶面长大为薄片状体系.弹性常数C₃₁和C₃₂在相变前被逐渐硬化,C₃₃则在相变前出现软化行为;当体系完全相变后,上述各弹性常数显示开始随体积压缩而迅速硬化,温度效应对晶格具有软化作用,可削弱C₃₃的硬化和软化过程;样品在压缩过程可出现孪晶结构,孪晶结构使晶格发生剪切变形.混合相中,hcp相势能比bcc相高,最大剪应力方向与bcc相反向;系统的偏应力与hcp相质量分数近似呈线性关系. 关键词： 结构转变 分子动力学 一维应变     

C2H2在金刚石（001）-（2×1）重构面上吸附的分子动力学模拟

利用Brenner半经验多体相互作用势和分子动力学模拟方法，研究了乙块（C₂H₂）分子在金刚石（001）-（2×1）重构表面上的碰撞动力学过程与化学吸附构型的关系.观察到C₂H₂在金刚石表面的6种吸附结构.约95％的吸附呈C₂H₂与表面形成两个σ单键的形式.讨论了轰击能量、入射位置及金刚石表面原子的空间位形对各种吸附构型形成的影响.还给出了化学吸附过程的分子快照，并讨论了C₂H₂分子与表面的能量交换关系. 关键词：     

采用Lennard-Jones原子间势研究(C60)N分子团簇的结构演化行为

采用描述原子间相互作用的Lennard-Jones势来描述C₆₀分子间的相互作用,考虑了每个C₆₀分子的一定位置取向,并采用最速下降法计算了IH,fcc,hcp,DH及SC五种典型结构满壳层(C₆₀)_N团簇(N<2000)的能量.结果显示:当尺寸较小(N<20)时,IH结构最稳定;当尺寸处于中等(50<N<300)时,HCP结构最稳定;当尺寸较大(300<N 关键词： 60团簇')" href="#">C₆₀团簇 取向 最速下降法 结构演化     

Templating a face-centered cubic (110) termination of C60

Scanning tunneling microscopy has been used to study C₆₀ overlayers on TiO₂(100)-(1 × 3). Initial adsorption preferentially occurs on O vacancies (Ti³⁺), evidencing a site-specific interaction dominated by substrate-adsorbate charge transfer. At saturation coverage the molecules are incommensurate with Ti³⁺ sites along [001], suggesting a delicate balance between intermolecular and substrate interactions. The unit cell of the C₆₀ overlayer is 13.8Å× 10.0 ± 0.5Å, consistent with the first layer of fcc C₆₀(110); molecules also adopt sites in the troughs of the (1 × 3) structure to form the second layer.     

FexMn1-x合金在GaAs(001)表面外延的结构和磁性

报道了对于0≤x≤1的Fe_xMn_1-x合金在GaAs(001)表面上分子束外延的结构与磁性的实验结果,当x>0.8时,Fe_xMn_1-x合金以单晶体心立方结构生长;当x<0.35时,则以单晶面心立方结构生长;对于0.35xMn_1-x生长的结构比较复杂,而正是在这一区域中,该合金发生了从铁磁相到反铁磁相的转变. 关键词：     

Chemical adsorption of C60 on diamond (100)(2×1) surfaces

Molecular-dynamics simulations (MDSs) and ab initiocalculations are used to investigate the adsorption behavior of C₆₀ molecules on a clean dimer-reconstructed (100)(2×1) diamond surface. C₆₀ molecules have some probability to be adsorbed on the diamond surface at low incident energy (6∼45 eV). Electron-density contours show strong chemical interaction between C₆₀ molecules and the substrate surface. The adsorption property depends strongly on the incident energy and the impacting point. An incident energy of 18 eV may be an appropriate energy to grow a sub-monolayer or monolayer C₆₀ film on a clean C(100)(2×1) surface at room temperature. Received: 5 July 2000 / Accepted: 17 October 2000 / Published online: 28 February 2001     

Electron-energy-loss spectroscopy of C60 monolayer films on active and inactive surfaces

The characteristics of interaction between C₆₀ molecules and Si(1 1 1)-7×7, Ag/Si(1 1 1)-√3×√3 R30° and layered material MoS₂ surfaces have been investigated using electron-energy-loss spectroscopy (EELS). The EEL spectrum of C₆₀/Si(1 1 1)-7×7 shows a new peak at loss energy of 2.7 eV. This indicates the existence of charge transfer from the substrate to C₆₀ molecules. The EEL spectrum of a C₆₀ monolayer film grown on a cleaved surface of MoS₂ is almost the same as that of bulk C₆₀. The EEL spectrum of a C₆₀ monolayer film on an Ag/Si(1 1 1) surface is quite different from that on a clean Si(1 1 1)-7×7 surface, although the films on those substrates have the same epitaxial arrangement. Furthermore, intensities of energy-loss peaks of C₆₀/Ag/Si(1 1 1) are slightly smaller than those of C₆₀/MoS₂ in spite of having the same loss-energy. This suggests that the interaction between C₆₀ molecules and the Ag/Si(1 1 1) surface is stronger than that between C₆₀ molecules and the MoS₂ surface.     

Theoretical simulation of STM image of C60 molecules on Si(100)-(2 × 1) surface

Theoretical simulation of STM image of C₆₀ molecules on Si(100)-(2 × 1) surface was performed by the DV-Xα-LCAO method. The results excellently reproduced the internal stripe pattern of the STM image of C₆₀ observed by experiment. We confirm that it is the interaction between C₆₀ and the Si substrate which causes this internal structure.     

Crystal structure of solid C70

Detailed analysis of the room temperature X-ray powder diffraction data of pure solid C₇₀ is reported. C₇₀ prepared by slow evaporation from toluene solution adopts an hcp structure (space groupP6₃/mmc) witha=10·53(1) A andc=17·24(1) A. C₇₀ sublimed on to Si wafer adopts an fcc structure witha=14·89(1) A. The occurrence of both the hcp and fcc phases is rationalized in terms of cohesive energy calculations. Theoretical calculations of the diffraction pattern for the hcp structure, taking into account (a) orientational disorder amongst the molecules (b) presence of stacking faults and (c) a fraction of the sample to be amorphous/microcrystalline is seen to provide very good agreement with the experimental diffraction pattern.