Contribution to the understanding of tribological properties of graphite intercalation compounds with metal chloride

Intrinsic tribological properties of lamellar compounds are usually attributed to the presence of van der Waals gaps in their structure through which interlayer interactions are weak. The controlled variation of the distances and interactions between graphene layers by intercalation of electrophilic species in graphite is used in order to explore more deeply the friction reduction properties of low-dimensional compounds. Three graphite intercalation compounds with antimony pentachloride, iron trichloride and aluminium trichloride are studied. Their tribological properties are correlated to their structural parameters, and the interlayer interactions are deduced from ab initio bands structure calculations

[Characterization of carbon materials by means of phonons and electrons]

Characterization of carbon materials by means of phonons and electrons This paper showns in how the measurement of the temperature variation of the thermal and electrical conductivities was successfully used as global tools to characterize carbonaceous materials. The temperature variation of the lattice thermal conductivity allows to compute directly the in-plane coherence length as well as the density of point defects and the shear modulus. The zero-field resistivity, which is very sensitive to the presence of lattice defects at low temperature, allows to compare samples of different structural perfections

Low-temperature Transport-properties of the Group-v Semimetals

The group V semimetals are first introduced by comparing their particular band structure with the more familiar typical metals or semiconductors. Recent results on the electrical resistivity, thermal conductivity and thermopower of bismuth, antimony and arsenic are reviewed, with particular emphasis on measurements performed at low and ultralow temperatures. The data are analysed in terms of the peculiar features of the electron and phonon scattering, and reference is made to the band structure and rhombohedral symmetry. Recent improvements in the interpretation of the results are discussed.Anglai

The Effect of Fiber Concentration On the Thermal-conductivity of a Polycarbonate Pitch-based Carbon-fiber Composite

Results of measurements of the thermal and electrical conductivities. of polycarbonate samples as a function of chopped pitch-based carbon fiber concentration are reported. The fibers, roughly 500 mum long, were found to be strongly oriented in the composite leading to a highly anisotropic thermal conductivity. Longitudinal thermal conductivities comparable to that of metallic alloys are obtained in the direction of the fibers, while in the transverse direction only a small increase in the thermal conductivity is observed. We proposed a new model which is a derivation of equations used for continuous fibers composites. This model is quite well in accordance with the linear dependence of the longitudinal thermal conductivity on the fiber concentration of our data. Taking into account the effect of the polymeric matrix, the importance Of contact resistances between fibers and their maximum packing as well as the qualitative differences between thermal and electrical conduction is discussed

Electronic structure and quantum transport in carbon nanotubes

The electrical properties of various forms of carbon nanotubes are presented with particular emphasis placed on individual multi-wall and single-wall tubes. After a brief survey of the electronic structure of single-wall carbon nanotubes, electronic transport mechanisms are overviewed in relation with the dimensionality of the carbon system. Typical quantum aspects of low temperature electronic conduction for low dimensionality encountered in some carbon nanotubes are discussed

Thermal conductivity of stretched and annealed poly (p-phenylene sulfide) films

The temperature variation of the thermal conductivities of as-prepared, mechanically stretched, as-prepared and then annealed PPS samples are presented. Unusually high thermal conductivity values are observed as compared to other polymeric materials. In agreement with the X-ray diffraction observations, the thermal conductivity of the oriented film is higher than that of the as-prepared or annealed films. The differences observed after stretching are comparable to those previously reported for polyethylene and polyacetylene films for the same draw ratios. These unusually high thermal conductivity values justify the use of PPS in devices where efficient heat dissipation, associated with electrical insulation, is required. (C) 2003 Published by Elsevier Science Ltd