Gas Storage in Fullerenes

Fullerenes and in particular C₆₀ have been shown to store effectively a wide range of gases from simple monatomic rare gases to diatomics and polyatomics. A review of the research in this area conducted at ANSTO is given. The trapping of Ar, Kr, Xe, and CO₂ are discussed in detail whilst preliminary results pertaining to N₂O, CH₄, CF₄, C₂H₆ and SF₆ are also reported. A range of techniques have been used to elucidate both the structure of the new fullerene intercalated solid and the trapped gas itself. The preponderant techniques used, include infra-red absorption spectroscopy (IR), X-ray powder diffraction a (XRD), neutron powder diffraction (NRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA).     

Synthesis, crystal structure and infrared study of LiEr(PO3)4

A single-crystal X-ray diffraction analysis has been performed on LiEr(PO₃)₄ prepared by the flux method. The compound crystallizes in the monoclinic system with space group C2/c and cell parameters: a = 16.262(2), b = 7.032(1), c = 9.549(2) Å and β = 125.95(1)°. The crystal structure was refined based on 1272 independent reflections with I > 2σ(I). Final values of the reliability factors were improven considerably: R(F²) = 0.0180 and wR(F²) = 0.0490. The LiEr(PO₃)₄ structure is characterized by infinite chains (PO₃)_n, extending parallel to the b direction. The ErO₈ dodecahedra and LiO₄ tetrahedra alternate on two-fold axes in the middle of four (PO₃)_n chains. The vibrational study by infrared absorption spectroscopy is reported.     

Fullerenes,Carbon Chains,and Interstellar Matter

Spectroscopy of carbon particles, fullerenes, and carbon chain molecules was the subject of a considerable part of my research work, as described in this article. In almost all cases, there existed a tight connection to problems in astrophysics and astrochemistry, aiming at a better understanding of interstellar matter. The bulk synthesis of fullerenes was a by-product of these efforts.     

木质陶瓷的X射线衍射和喇曼光谱研究

采用X射线衍射和激光喇曼光谱, 研究了以烟杆和酚醛树脂为原料制备木质陶瓷炭化过程中结构的变化特征. 研究结果表明, 炭化温度的升高可以使木质陶瓷XRD谱图中衍射峰增加, 强度增大, 同时木质陶瓷中石墨微晶的平均层间距d₀₀₂减小, 堆积厚度L _c增加, 微晶直径 L _a在973K出现转折点; 木质陶瓷的喇曼光谱图为典型的类石墨炭材料的喇曼谱图, 只出现了表征无序结构的D线和表征石墨结构的G线, 且表征无序化度的二者积分强度比R值随炭化温度的升高先增后减, 而根据Tuinstra-Koenig 经验式计算得到的微晶直径L a值表现出与R值相反的规律; 两种分析方法的结果较为一致, 均表明木质陶瓷结构在973K发生根本改变, 说明喇曼光谱有望成为木质陶瓷结构的快速测试方法.     

Charge Transfer and the Route to Superconductivity in the Doped Fullerenes

A brief review is presented discussing the role of charge transfer and the appearance of superconductivity in the three-dimensional (3D) alkali-metal-doped fullerene compounds (A₃C₆₀). An argument is made that similar phenomenology may occur in two dimensions (2D) when a C₆₀ monolayer is doped by charge transfer from an adjacent planar metal layer. Illustrative data are presented showing that charge transfer gives rise to a decrease in resistance when C₆₀ is deposited onto a thin smooth nickel film. Accordingly, the physics of charge transfer and electron delocalization, which plays such an important role in the superconductivity of the 3D A₃C₆₀ compounds, could well play a similar role in these 2D analogues where a C₆₀ monolayer is doped to a conducting state by charge transfer from an underlying metal.     

Localization and Superconductivity in Intercalated Fullerenes

The model of superconductivity in the intercalated fullerenes based on arising of the valence bond between two neighbouring alkali-metal atoms is proposed. This model explains all the currently available experimental data concerning superconductivity in these compounds. Among them are the absence of superconductivity in A _x C₆₀ with even x, the dependence of the critical temperature on the disorder level and the carrier concentration, and the shape of the density of states near the Fermi level as a function of voltage in tunnelling spectroscopy.     

SiO2-Li2O玻璃结构与紫外透过性能的研究

采用红外光谱和X射线光电子能谱方法研究了SiO2-Li2O玻璃的结构与紫外透过性能的关系.结果表明:玻璃网络结构加强且非桥氧数量低时,紫外透过性能好;反之,网络结构削弱、破坏以及非桥氧数量提高,紫外透过性能下降.在SiO2-Li2O玻璃中,随着Li2O含量的增加,Si-O结构不饱和程度进一步增加,产生断网结构,非桥氧数量上升,导致紫外透过性能降低.     

Characteristics of the precursors and their thermal decomposition during the preparation of LiNbO3 thin films by the Pechini method

Lithium niobate thin films have been deposited on Pt/Ti/SiO₂/Si(100) substrates by Pechini method. Characterization of the initial precursor solutions containing citric acid (CA), niobium and lithium ions has been performed by Fourier transform infrared spectroscopy, Raman spectroscopy and carbon nuclear magnetic resonance spectroscopy. The results indicate that citric acid coordinate to niobium ions to form a niobium-CA complex through one terminal carboxyl group, the hydroxyl group and the central carboxyl group as a tridentate ligand. The thermal decomposition of the Li-Nb precursors gel powder has been studied and the results show that LiNbO₃ phase is formed directly from the thermal decomposition of the precursor gel. By heat-treatment at 600 °C for 2 h, polycrystalline LiNbO₃ thin films with smooth and crack-free surface could be achieved.     

乙炔的等离子体热解产物:富勒烯的合成

乙炔在高频等离子体电弧中高温分解,连续批量合成炭黑烟炱.高分辨透射电镜(HRTEM)观察发现,炭黑粒子大小约为25nm,由无定形碳和结晶不完整的石墨碎片组成.采用紫外/可见吸收光谱(UV-Vis),付立叶变换红外光谱(FT-IR)等分析方法,对其甲苯提取液及结晶产物进行了初步的成份确认,发现其中含有C60/C70富勒烯成份,粗含量达到烟炱的3%左右.     

Textural and chemical properties of zinc chloride activated carbons prepared from pistachio-nut shells

The effects of activation temperature on the textural and chemical properties of the activated carbons prepared from pistachio-nut shells using zinc chloride activation under both inert nitrogen gas atmosphere and vacuum condition were studied. Relatively low temperature of 400 °C was beneficial for the development of pore structures. Too high an activation temperature would lead to sintering of volatiles and shrinkage of the carbon structure. The microstructures and microcrystallinity of the activated carbons prepared were examined by scanning electron microscope and powder X-ray diffraction techniques, respectively, while Fourier transform infrared spectra determined the changes in the surface functional groups at the various stages of preparation.     

Thermal, spectroscopic and magnetic properties of the CoxNi1−x(SeO3)·2H2O (x = 0, 0.4, 1) phases: Crystal structure of Co0.4Ni0.6(SeO3)·2H2O

The Co_xNi_1−x(SeO₃)·2H₂O (x = 0, 0.4, 1) family of compounds has been hydrothermally synthesized under autogeneous pressure and characterized by elemental analysis, infrared and UV-vis spectroscopies and thermogravimetric and thermodiffractometric techniques. The crystal structure of Co_0.4Ni_0.6(SeO₃)·2H₂O has been solved from single-crystal X-ray diffraction data. This phase is isostructural with the M(SeO₃)·2H₂O (M = Co and Ni) minerals and crystallizes in the P2₁/n space group, with a = 6.4681(7), b = 8.7816(7), c = 7.5668(7) Å, β = 98.927(9)° and Z = 4. The crystal structure of this series of compounds consists of a three-dimensional framework formed by (SeO₃)²⁻ selenite oxoanions and edge-sharing M₂O₁₀ dimeric octahedra in which the metallic cations are coordinated by the oxygens belonging to both the selenite groups and water molecules. The diffuse reflectance spectra show the essential characteristics of Co(II) and Ni(II) cations in slightly distorted octahedral environments. The calculated values of the Dq and Racah (B and C) parameters are those habitually found for the 3d⁷ and 3d⁸ cations in octahedral coordination. The magnetic measurements indicate the existence of antiferromagnetic interactions in all the compounds. The magnetic exchange pathways involve the metal orbitals from edge-sharing dimeric octahedra and the (SeO₃)²⁻ anions which are linked to the M₂O₁₀ polyhedra in three dimensions.     

2D and 3D Crystal Forms of the C36 Fullerenes: Geometrical and Electronic Structure

Abstract

In the present work calculations of geometrical structure and electronic properties of the covalent crystal consisted of hexagonal close packaged layers of C₃₆ fullerenes in 2D & 3D cases are carried out. The analysis of the stability and formation paths of such crystal according to PM3 semiempirical method was performed. Extended Huckel theory has been applied to electron spectra calculations. Comparison of the structure with similar fullerene and nanotube structures was carried out and effect of geometry to electron properties is discussed. In the work the values of 6.695 and 6.763 Å for the lattice constants were obtained with good agreement with experiment (Piskoti, C.; Yarger, J.; Zettl, A. C₃₆, a new carbon solid. Nature 1998, 393, 771), and value of 1.50 eV in 2D case and 1.88 eV in 3D case was obtained for bandgap.     

一种测定晶体取向及其分布的简便XRD方法

提出了旋转定向测试法，其原理是使试样的在粉末X射线衍射仪上进行θ扫描的同时绕其端面法线自转，增加了晶面法线通过衍射平面的机会。通过这种方法可直观地区分取向多晶，准单晶或者单晶体，评定研制过程中准单晶和择优取向材料的晶体品质，确定单晶，准单晶及择优取向等材料的晶面相对宏观端面的晶向偏离角和取向分散度，还可对单晶体材料进行三维晶面定向。旋转定向法测试晶体取向具有快速简便，一机多用，精度高等优点，在电子、光学、磁性，机械等材料研究领域具在广泛的应用。     

洋葱状富勒烯的研究进展

详细介绍和分析了洋葱状富勒烯(OLFS)的各种制备、纯化和改性方法,概述了其性能和应用的最新研究进展.OLFS特有的力、电、光、磁、吸附、催化等物理及化学性能,使其在工程、电子信息、能源、生物医学、化学化工、国防等领域有着广阔的应用前景.为此,应进一步围绕OLFS类新型纳米碳材料的制备、表面修饰、功能化、实际应用等各个环节的物理与化学问题进行探索,为该类功能材料的实际应用提供参考依据.     

微波等离子体法合成洋葱状富勒烯的研究

在微波等离子体条件下, 以乙炔炭黑/二茂铁为原料, 低温合成纳米洋葱状富勒烯(Nano-structured Onion-like Fullerenes: NSOFs). 采用HRTEM、Raman和XRD等分析方法对产物的形貌、尺寸、微观结构及其物相结构进行了表征. 结果表明, 以乙炔炭黑/二茂铁为原料可大量合成NSOFs, 其外观呈准球状或多面体状、实心、直径分布均匀, 最外碳层由闭合的、呈波浪状的石墨片构成.     

共沉淀法制备ZrW2O8及其中间产物的晶体结构

以仲钨酸铵[（NH4）10W12O41·5H2O]和氧氯化锆（ZrOCl2·8H2O）为原料,采取共沉淀法制备具有负热膨胀系数的钨酸锆（ZrW2O8）。采用X射线衍射仪（XRD）分析合成过程的前驱体、中间体和最终产物等的晶体结构,并采用FullProf-Suite程序和Material Studio程序分别对ZrW2O8晶体的XRD数据进行处理,精化修正其原子坐标参数和晶体结构参数。结果表明,前驱体结构呈无定形态;中间体的结晶度为33．66％;最终产物为立方晶系的ZrW2O8,空间群为P213（198）,晶胞参数α0为0．91598nm,晶胞体积为0．76852nm^3,衍射峰指标化的可靠性因子F（30）=57．1（44）,峰形因子RP为0．2519,权重因子Rwp为0．1343。     

The effect of chelating/combustion agent on catalytic activity and magnetic properties of Dy doped Ni–Zn ferrite

The spinel ferrite Ni_0.8Zn_0.2Fe_1.98Dy_0.02O₄ was prepared by sol–gel low temperature autocombustion method using four different chelating/combustion agents: citric acid, tartaric acid, urea and cellulose. Infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) specific surface area measurement, the catalytic H₂O₂ decomposition and the magnetic behavior were employed to investigate the influence of the combustion agents on structural characteristics, catalytic activity and magnetic properties. Spinel-type phase in the nano-scale domain was accomplished during sol–gel synthesis and was confirmed by XRD and IR. The best catalytic activity is belonging to the sample obtained using urea, which shows the smallest grain size (SEM), the highest specific surface area (BET measurements) and DyFeO₃ phase (XRD), while ferrimagnetic behavior prevails for all the samples independently of fuel agent.     

Interactions Between the Molecules of Different Fullerenes

Abstract

Generalizing the procedures of Girifalco and of Verheijen et al. and using results of the preceding work the interaction potential between the molecules of different fullerenes C _n and C _m at orientationally disordered (high‐temperature solid and gaseous) phases has been derived. We have calculated the coefficients for interactions of the C₆₀ molecule with the molecules of higher fullerenes from C₇₀ to C₉₆ and with the smaller one, C₃₆. The dependence of the minimum point r ₀ and of the depth of the potential well ? on the numbers of the atoms in the molecules m and n has been investigated.     

Oxidation study of polycrystalline InN film using in situ X-ray scattering and X-ray photoemission spectroscopy

Oxidation process of polycrystalline InN films were investigated using in situ X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS). The films were grown by dc sputter on sapphire (0001) substrates and were oxidized in air at elevated temperatures. The XRD data showed that the structure of the films changed to the bixbyite In₂O₃ (a = 10.11 Å) above 450 °C. Chemical configurations of the sample surfaces were investigated using high-resolution XPS. For the non-intentionally oxidized InN film, XPS analysis on the In 3d peak and the N 1s main peak at 396.4 eV suggests that indium and nitrogen are bound dominantly in the form of InN. An additional peak observed at 397.4 eV in the N 1s photoelectrons and the O 1s peaks indicate that the InN film surface is partly oxidized to have InO_xN_y configuration. After oxidation of the InN film at elevated temperature, the O 1s spectrum is dominated by In₂O₃ peak, which indicates that the structure is stable chemically with In₂O₃ configuration at least within the XPS probing depth of a few nm.