摘要:

Ax(C6H6)yC60(with A = K, Rb and 3<x<6, 0.5<y<3) ternary compounds have been prepared. Their structure presents some differences with original AxC60compounds. Benzene effect on the transition temperature of superconducting phases was investigated by magnetic studies. The most interesting result is that intercalation of C6U6into non superconducting A6C60led to a superconducting compound.

ISSN:1058-725X    

DOI:10.1080/10587259808045327

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The synthesis of fullerides of alkali metals (Na, K) and alkali-earth metals (Sr, Ba) was performed under the mechanical and chemical activation in the organic solvent. Under mechanical activation of synthesis the time of the complete transformation depends on: i) the nature of solvent, ii) ratio metal/fullerenes and iii) the chemical activity of metal and method of synthesis.

ISSN:1058-725X    

DOI:10.1080/10587259808045328

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

X-ray diffraction and resistivity measurements on bulk single-wall carbon nanotube material are described. The tubes self-organize during growth into a triangular lattice. The temperature dependence of the resistivity is consistent with a metallic system at high temperatures.

ISSN:1058-725X    

DOI:10.1080/10587259808045329

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Though the presence of nanotubes in a carbon sample may be clearly detected by electron microscopy, yet it has been difficult to determine if the nanotubes in question belong to a Russian doll or scroll type. This work shows how a chemical reaction with ferric chloride or with potassium metal reveals the differences between the two types of intratube shell arrangement. Scroll nanotubes are intercalated by alien molecules which penetrate from the side of the scroll and fill the intershell spaces. The corresponding intershell spaces expansion was directly observed in this work by TEM. Russian doll nanotubes do not enter the reaction and stay intact. The reaction with scroll nanotubes is accompanied with a remarkable tube swelling which is easily observed by scanning electron microscopy. The presence of intercalated nanotubes may also be detected by X-ray diffraction and Raman spectroscopy.

ISSN:1058-725X    

DOI:10.1080/10587259808045330

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The successful intercalation of lithium into catalytic carbon nanotubes under high pressure conditions is reported. The compounds obtained have Li contents as high as 1–2 Li/ lC and repeat distances along the c-axis 3.69–4. 11 Å, preserving the tubular structure of the nanotubes. XRD, Infrared spectroscopy and7Li NMR investigations are performed to characterize the compounds obtained.

ISSN:1058-725X    

DOI:10.1080/10587259808045331

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Graphite fragments of nanometer size, called nanographite, have a different electronic structure than both bulk graphite and aromatic molecules. In particular, if they have zigzag edges, a sharp peak in the density of states at the Fermi level is generated, suggesting to cause Fermi instability. We have studied the lattice distortion and the possible magnetization based on the model of graphite ribbons with a nanometer width, by taking into account the electron-phonon and electron-electron interactions in the form of a tight binding model.

ISSN:1058-725X    

DOI:10.1080/10587259808045332

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Catalytic synthesis and characterization of multi-wall fullerene nanotubes are presented. Supported transition metal catalysts were prepared by different methods and were tested in the decomposition of hydrocarbons. Reactions were carried out in a fixed bed flow reactor at 700°C at atmo-spheric pressure. Both activity and selectivity of catalyst samples depended mainly on the following parameters: catalyst support, transition metal, initial reactant, and reaction temperature. The quality of the product was charac-terized by TEM. Although the ends of these catalytically produced carbon nanotubes are often closed by fullerenic half-onions, they can be opened with ease in a relatively gentle liquid-phase oxidation procedure. Neither drastic purification process with HF nor oxidative treatment destroyed the quality of the tubes. IR and XPS investigations confirmed that carbon nano-tubes having inner diameter larger than 1–2 nm show graphitic feature.

ISSN:1058-725X    

DOI:10.1080/10587259808045333

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Carbon nanotubes synthesized by decomposition of acetylene over silica-supported cobalt catalysts were fluorinated in different conditions : at room or high temperature, ca. 500°C. The electrochemical behaviour of these carbon nanotube fluorides as electrode materials in a lithium cell was investigated using a liquid electrolyte. Results are compared to those obtained with graphite fluoride compounds which present a well known high electrochemical performance.

ISSN:1058-725X    

DOI:10.1080/10587259808045334

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We report on the specific heat,C(T), measurements of a new carbon phase synthesized by condensation of high temperature carbon gas. For the adequate description of theC(T) dependence, the model of specific heat for quasi-one-dimensional crystals has been applied. By means of X-ray and specific heat measurements it has been found that the material is a metastable phase under the normal conditions, undergoing the transformations to the amorphous state upon heating aboveT≈350 K.

ISSN:1058-725X    

DOI:10.1080/10587259808045335

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In the structure of the clathrate-type silicides M8Si46and MxSi136(M ˭ Na, K, Rb, Cs, Ba; 0 ≤ x ≤ 24), the silicon atoms form 3D covalent sublattices which correspond to the association of two kinds of fullerene-like cages : Si20and Si24, and Si20and Si28respectively. The M atoms are trapped at the centre of all or part of the two different cages and are distributed according to a A15 and a C15 type sublattice, respectively. Due to their clathrate-type structure, these silicides exhibit original and interesting physical properties. The two structures are described and a short review is given on the previous and recent developments on these cage-like compounds.

ISSN:1058-725X    

DOI:10.1080/10587259808045336

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor