共查询到20条相似文献,搜索用时 31 毫秒
1.
G. E. Gadd M. Collela M. Blackford A. Dixon P. J. Evans D. Mcculloch 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(1-2):65-76
Abstract We have shown that Ni metal particles when melted in the presence of C60 form graphitic layers around themselves with the Ni remaining as pure metal and without any evidence of carbide formation. We have successfully encapsulated particles over several orders of magnitude of size from ~10 nm to several microns. The process has been observed taking place in real time using transmission electron microscopy (TEM). The process was not observed when graphite powder was used instead of C60 powder and the Ni similarly heated to melting point, using the electron beam. Heating a mixture of Ni and C60 powders together in a conventional manner also produced encapsulated Ni particles. This suggests that the encapsulation method is thermal in nature although the electron beam does offer the ability to control the process for individual particles. Further research has shown that the encapsulation process can also occur at temperatures as low as 800° C by a catalytic route. We have extended the work of heating a metal in the presence of fullerenes and have effectively encapsulated other metals such as Fe, Co, Ho, Cu and Au. 相似文献
2.
Ram Seshadri V. Vijayakrishnan A. K. Santra A. Govindaraj C. N. R. Rao 《Fullerenes, Nanotubes and Carbon Nanostructures》1993,1(1):75-91
Based on UV and X-ray photoelectron spectroscopy, it is shown that nickel metal clusters deposited on solid C60 and C70 films cause marked changes in the valence band spectra. In addition, the C 1s core-level of the fullerenes shift to lower binding energies while the Ni 2p3/2 core level shifts towards higher binding energies, especially at small metal coverages. These observations signify the occurrence of charge-transfer from the nickel metal to the fullerene. We also show that CO adsorbs weakly on C60 and C70 surfaces. 相似文献
3.
R. Kamalakaran A. K. Singh O. N. Srivastava 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(3):283-298
We report the transformation of C60 into diamond by electron beam pulse annealing of flash evaporated films (at 10-6 torr) of C,60, or by direct evaporation of C60 in helium (100 torr) atmosphere. The formation of filament and microcapillaries (tubulene-like structures) by electron beam annealing of the C60 deposit is also reported. 相似文献
4.
G. E. Gadd M. James S. Moricca P. J. Evans R. L. Davis 《Fullerenes, Nanotubes and Carbon Nanostructures》1996,4(5):853-862
We communicate how C60 Hot Isostatically Pressed (HIPed) at 200° or 400°C with a pressure of 1.7 kbar of Ar produces the new fullerene-rare gas compound Ar1C60. We have shown, using Xray powder diffraction and subsequent Rietveld analysis, that this solid can be characterised stoichiometrically as Ar1C60- The stoichiometry has also been confirmed by thermal gravimetric analysis (TGA) showing 5% by weight to be Ar (expected=5.25%). The presence of Ar is confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). This material is found to be remarkably stable to loss of Ar over several weeks at room temperature. This represents the first full characterisation of an interstitial rare gas fullerene compound. 相似文献
5.
E. Kolodney B. Tsipinyuk A. Bekkerman 《Fullerenes, Nanotubes and Carbon Nanostructures》1998,6(1):67-102
We have studied thermally activated decay processes of an ensemble of isolated superhot C60 molecules in molecular beams by several different methods. Highly vibrationally excited C60 molecules in effusive or supersonic beams (with average vibrational energy of 10-20 eV) were generated in an all ceramic, two-stage high temperature nozzle source. the decay kinetics due to various decay processes of the initially canonical ensemble was followed by a mass spectrometric methods for a large range of initial temperatures (To=1100 - 1950 K). the processes studied are: (1) fragmentation (C2 emission) of the neutral C60 (2) C2 emission from the C+60 ions (3) black-body like radiative cooling, and (4) delayed electron emission. the experiments described here are: (a) Depletion of the integrated C60 flux. (b) Analysis of C60 time-of-flight distributions. (c) Dependence of electron impact induced ionization/ fragmentation of C60 upon its initial thermal excitation, and (d) Thermal energy dependence of delayed electron emission. It is shown that thermal kinetics models using a single set of independently measured parameters uniquely reproduce all the experimental observations. the models take into account the different cooling processes and their time evolution. We analyze in detail the evolution of the initially canonical vibrational energy distribution during the flight time to the detector as it is gradually being distorted due to evaporative and radiative cooling mechanisms. It is concluded that the correct parameters to be used for describing the thermally activated decay kinetics of superhot C60 are activation energy of Eo = 4.3 - 4.8 eV for the neutral fragmentation channel C60 → C58 + C2 and E1=4.0 - 4.3 for the ion fragmentation channel C+60→ C+58 + C2, and corresponding pre-exponential factors of Ao = A1 = 2.5 × 1013 sec-1. the emissivity coefficient for black body like radiation was found to be ε = 4.5 × 10-5. 相似文献
6.
G. E. Gadd P. J. Evans S. Kennedy M. James M. Elcombe D. Cassidy S. Moricca J. Holmes N. Webb A. Dixon P. Prasad 《Fullerenes, Nanotubes and Carbon Nanostructures》1999,7(6):1043-1143
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). 相似文献
7.
Synthesis of fullerenes from carbon powder by using high power induction thermal plasma 总被引:4,自引:0,他引:4
Radio frequency (rf) inductively coupled thermal plasma (ICTP) was used to fabricate fullerenes (C60,C70, etc.) by direct evaporation of carbon powder injected into the plasma. Spectroscopic observation of the plasma was made for molecular band spectra of C2 and atomic lines of C. The formation of fullerenes C60 and C70 as well as higher fullerenes were checked and recognized by high performance liquid chromatography (HPLC) and time-of-flight mass spectrometer (TFMS). The suitable conditions for the synthesis of fullerenes within the experimental conditions adopted were 10-kPa plasma pressure, with a considerably higher flow rate of approximately 150 l/min for mixed-gas condition of Ar, He and CO2, with carbon powder of average diameter 20 μm. The results showed that the productivity of fullerenes has a relation to the intensity of C2 molecular and C atomic spectra from the induction plasma. Mixing of Si with C particles has a kind of role in enhancing the synthesis rate of fullerenes C60, as well as the higher order fullerenes. 相似文献
8.
C. Sekar C. R. V. Rao C. Subramanian P. Ramasamy 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(3):343-358
Good quality C60 crystals have been grown from high purity C60 powder and fullerene mixture (C60/C70) by vacuum sublimation method. The grown crystals were characterized with Optical microscopy, SEM, powder XRD, High Performance Liquid Chromatography and Raman spectroscopic analyses. 相似文献
9.
Frans J. M. Rietmeijer Alessandra Rotundi Dieter Heymann 《Fullerenes, Nanotubes and Carbon Nanostructures》2004,12(3):659-680
A transmission electron microscope (TEM) study of individual soot grains forming fluffy carbon particles produced using the arc-discharge technique revealed close-packed arrangements of single-wall ring structures with average diameters of 0.7, 1.1, 3.0, 5.5, and 8.2 nm. These structures were hypothesized to be C60 and giant, C540, C960, and C1500, fullerenes that could form by coalescence during condensation and soot agglomeration, although in situ solid-state growth cannot be excluded. Mass spectroscopy and high performance liquid chromatography (HPLC) chromatography of the samples confirmed the presence of C60 fullerene in all samples giving confidence to the giant fullerene growth scenario. Our results suggest that fullerenes could be common in soot grains produced by this technique as well as being an important carbon phase in C-rich accretion disks around young stellar objects and among the dust in the interstellar medium. 相似文献
10.
Andrzej Graja 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(6):1219-1242
We have summarized the results of studies of the molecular dynamics of C60 and its complexes by electron and vibrational spectroscopies. It was shown that the spectral methods are an important probe of the symmetry, bonding and dynamics of the fullerene molecules, as well as of the fullerite and the C60-derived fullerides. 相似文献
11.
Shenyi Wang Lei Zhu Jianzhong Lu Peinan Wang Yufen Li Yulong Sun Ruifang Cai Zu'en Huang 《Fullerenes, Nanotubes and Carbon Nanostructures》1994,2(1):49-57
We have studied the fragmentation and aggregation of C60 and its radical adducts RnC60 by laser-desorption TOF mass spectrometry in the positive and negative ion channels. The mechanism of the formation of daughter fullerenes in the negative ion channel and the enhancement of fullerene aggregation products have been discussed. We consider that the electron transfer process between neutral cage-like clusters and the radicals is responsible for the appearance of strong mass peaks of daughter fullerene anions in the case of C60 radical adducts. The effects of the radicals on the fullerene aggregation process have been discussed. 相似文献
12.
Synthesis of Fullerenols from Halofullerenes 总被引:1,自引:0,他引:1
Pavel A. Troshin Antonina S. Astakhova Rimma N. Lyubovskaya 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,13(4):331-343
Halogenated fullerenes were used as reagents to prepare fullerenols. Depending on reaction conditions two types of substances (complex mixtures of products with average compositions C60OnHm, n=10-26, m=14-30 and C60OnHmMk, M=K, Na; n=17-24, m=16-28, k=3-8) possessing essentially different water solubility were obtained. Highly soluble metal-containing species are most likely ionic compounds similar to metal derivatives of alcohols-alcoholates. An electron withdrawing effect of the carbon cage could make alkali metal fullerenolates (C60(OH)x(OM)y) inert towards hydrolysis. Halogens were selectively substituted when fullerene bromides and chlorides were treated with silver trifluoroacetate. Fullerenol esters C60(OOCCF3)n formed were then hydrolyzed to form C60(OOCCF3)x(OH)y. Attempts to cleave all ester groups in C60(OOCCF3)x(OH)y failed in acidic media, while alkaline hydrolysis was accompanied by unselective polyhydroxylation of the fullerene cage. 相似文献
13.
R. Popescu D. Macovei A. Devenyi A. Belu-Marian D. G. Fratiloiu R. Manaila 《Fullerenes, Nanotubes and Carbon Nanostructures》1999,7(1):77-90
In case of a metal finely dispersed in a C60 matrix, the metal-to-C60 charge transfer lowers the interface energy. The total cohesive energy per metal atom Etot was estimated for Au clusters in fullerite. The results show that, for a charge Qf ≥ 1 electron (e) transferred from the metal clusters to each C60 cage, a minimum appears in Etot, defining a most stable cluster size. Thereby, the equilibrium dispersion state of the metal in the fullerite matrix depends on Qf. 相似文献
14.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2003,11(4):295-316
Hydrogenated C60 fullerene, C60H36 was prepared in different solvents using Zn/HCl as reducing agents. The structure of C60H36 was confirmed both by electronic and FT-IR spectroscopy and the purity of the reaction product was checked by HPLC analysis. It has been confirmed that C60H36 is not stable in air, especially in presence of light which enhances the oxidation. The oxidation of C60H36 was studied by FT-IR spectroscopy and by differential scanning calorimetry (DSC) in air; the formation of hydroxyl groups on the fullerene cage and ketonic groups (involving cage breakdown) have been detected. Furthermore, the action of O3 on C60H36 was investigated and it has been found that O3 exerts practically the same effect of air but causing an enhanced cage breakdown. The thermal stability of C60H36 was checked by a thermogravimetric analysis (TGA) coupled with a differential thermal analysis (DTA) under N2 flow. The vaporization of C60H36 occurs at very high temperature: the DTA trace has shown an endothermic peak at 540°C (at a heating rate of 20°C/min). C60H36 shows an electronic absorption spectrum with a maximum at about 217 nm and it is able to match both in position and in half width the peak at 217.5 nm observed in the spectrum of the interstellar extinction of light which was attributed to hydrogenated, radiation processed and thermally annealed carbon dust. Similarly, the absorption spectrum of C60H36 is able to match several infrared emission bands (called UIBs) detected from certain astrophysical objects like the protoplanetary nebulae (PPNe). It is proposed that hydrogenated fullerenes can be used as model compounds in the laboratory simulation studies of interstellar carbon dust. 相似文献
15.
Katsumi Yoshino Kazuya Tada Akihiko Fujii Kazuhisa Hosoda Shin-ichi Kawabe Hirotake Kajii Masaharu Hirohata Rahmat Hidayat Hisashi Araki Anvar A. Zakhidov Ryu-ichi Sugmoto Masahiko Iyoda Mitsuo Ishikawa Toshio Masuda 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(7):1359-1386
C60 doping into conducting polymer with highly extended π-electron system in the main chain induces remarkable quenching of photoluminescence in conducting polymer and drastic enhancement of photoconductivity. These results can be explained in terms of photo-induced charge transfer between conducting polymer and C60. That is, photoexcited excitons or exciton-polarons on conducting polymer are effectively dissociated at C60 molecules transferring electrons to C60. Photoexcitation of C60 results in the transfer of hole from C60 to conducting polymer. These novel C60 doping effects have been observed not only in conducting polymers with non-degenerated ground state structures but also those with degenerated ground state structure such as di-substituted acetylene polymers with solitonic electronic systems.
Highly effective photo-induced charge transfer has been also observed in conducting polymer/C60 heterojunctions, which are interpreted as donor (D)-acceptor (A) photocell. Based on this finding we have demonstrated an organic photovoltaic cell with D-A double heterojunction, Al/C60/OEP/conducting polymer/TTO, in which OEP is octaethylporphine as an light absorbing antenna molecule. Novel characteristics have also been observed in various other junction devices utilizing C60 doped conducting polymer.
Granular and multiphase superconductivity has been found in C60-conducting polymer-alkali metal composites.
Effect of other type of fullerenes such as C70, modified C60 and C60 polymers, and also effect of C60 doping in polysilanes and their derivatives have also been studied. 相似文献
Highly effective photo-induced charge transfer has been also observed in conducting polymer/C60 heterojunctions, which are interpreted as donor (D)-acceptor (A) photocell. Based on this finding we have demonstrated an organic photovoltaic cell with D-A double heterojunction, Al/C60/OEP/conducting polymer/TTO, in which OEP is octaethylporphine as an light absorbing antenna molecule. Novel characteristics have also been observed in various other junction devices utilizing C60 doped conducting polymer.
Granular and multiphase superconductivity has been found in C60-conducting polymer-alkali metal composites.
Effect of other type of fullerenes such as C70, modified C60 and C60 polymers, and also effect of C60 doping in polysilanes and their derivatives have also been studied. 相似文献
16.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2003,11(2):105-113
It is shown by HPLC diode-array analysis that the C60 and C70 polymeric fullerene oxides ([C60]-PFOs and [C70]-PFOs) which are polymeric ozonides, are composed by nine different components. The ozonide derivatives of C60 and C70 have been proved to be practically analogous in chemical structure and composition. The most important component of both [C60]-PFOs and [C70]-PFOs accounts for about 3/4 of each sample. The overozonation of [C60]-PFOs in methanol has been studied and shown to not produce any significant changes. 相似文献
17.
J. Piechota P. Byszewski R. Jablo sk K. Antonova 《Fullerenes, Nanotubes and Carbon Nanostructures》1996,4(3):491-507
The electronic structure of C60 molecules with carbon substituted by other elements such as boron or nitrogen has been calculated for molecules in the singlet state with even number of electrons. Therefore, in the case of boron and nitrogen substituents, calculations have been performed for ionized molecules. The results obtained from our density functional calculations prove than in the C60-x-yBxNy molecules both HOMO and LUMO levels are split due to the lower symmetry of the molecule Influence of deformation of C60 molecules on electronic states, which is interesting because fullerenes may undergo deformation in solvate crystals, is also shown These C59B and C59N, as well as C58BN molecules are of special interest because samples containing such species can be prepared The Electron Spin Resonance (ESR) in those samples differs from the results obtained in pure C60 samples, it consists of several lines which are very sensitive to the temperature. 相似文献
18.
V. S. D. Muthu K. A. Sood A. Govindaraj N. R. C. Rao 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(6):755-764
We report Raman studies on powder samples of the charge transfer complex (TTF)x C60Br8 at room temperature. The phonons show considerable softening with respect to the frequencies observed in the Raman spectrum of solid C60 Brg. The strongest mode at 1464 cm-1 in C60Br8 is red shifted to a doublet with peaks at 1414 and 1421 cm-1, implying an average phonon softening Δω of -47 cm-1. A comparison with the phonon softening of the corresponding Ag(2) mode in alkali-doped C60 (Δω ~ - 36 cm-1 for A6C60, A = K, Rb or Cs) suggests that 8 electrons are transferred per C60Br8 molecule in the charge transfer complex. The mode at 503 cm--1 in C60Br8 is shifted upwards, similar to that in A6 C60 compounds. 相似文献
19.
Zden
k Slanina Chihiro Miyajima Xiang Zhao Ludwik Adamowicz Eiji
sawa 《Computational Materials Science》2000,18(3-4):308-314
Semiempirical quantum-chemical PM3 calculations are reported for a new class of exohedral metallo-fullerenes – metal-coated or metal-covered fullerenes: C60Mn and C70Mn. The exohedral species have been observed in gas phase, however, their geometrical and electronic structures are not known yet. Relatively-even metal-atom distributions over the fullerene rings are considered – such regular forms are computed for M = Be, Mg, Al. Three selected types of stoichiometries are treated in particular: C60M12/C70M12 (metal atoms above all pentagons), C60M20/C70M25 (metal atoms above all hexagons), and C60M32/C70M37 (metal atoms above all rings). If an odd number of electrons should result (Al), the related cation is computed, or one metal atom added or removed. This interesting arrangement above the rings is possible only for some types of atoms, while other elements are localized above bonds or atoms, or inside the cage, or even react and destroy the cage. Other limitation comes from the parametrization of the computational technique used – the PM3 semiempirical method is parametrized only for some selected metals. Metal-layer atomization heats are suggested as a stability measure. Structural characteristics are also presented and interesting reductions of the cage symmetry are found. Their relationship to Jahn–Teller effect is discussed. The metal covered fullerenes can represent models for metal catalysis in the nanotube synthesis and could eventually lead to new interesting materials. 相似文献
20.
《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(4):249-256
Fullerene+iron (C60+Fe) mixture plasmas were produced and studied in the ECR ion source of ATOMKI. The two main components of the plasma were obtained by different filament ovens. In this series of measurements we concentrated on the maximum ratio of C58 (damaged fullerene) in the plasma. C58 is less stable than C60 and the probability to form new materials is higher. Using this method we produced molecules of mass M=752 both in single- and double-charged states with beam intensities of 8 · 10-10A and 2 · 10-10A, respectively. We identified this beam as a mixture of FeC58, O2C60 and CO2C59, while the experiment did not give information on the exact location of the iron and oxygen in the carbon ball. 相似文献