S. L. Fang

Single-wall carbon nanotubes from coal

Abstract We demonstrate that single-wall carbon nanotubes (SWNT) can be produced by an arc-discharge method using a catalyzed coal carbon source. Characterization by resonant Raman scattering and electron microscopy confirm that this material contains SWNT with properties similar to graphite-derived SWNT. `Web-like material from our growth process has an estimated yield of 45 wt.% of carbon as SWNT, while the average chamber yield is approximately 20 wt.% C, as determined by FT-Raman and HRSEM measurements.

Physical properties of CVD-grown Se—carbon films

Abstract A novel chemical vapor deposition (CVD) approach based on the thermal decomposition of an aromatic hydrocarbon in the presence of Se vapor is used to grow films of layered Se—carbon compounds. In principle, this technique can produce a wide variety of new carbon-based materials, for example, graphite intercalation compounds (GICs) which, for kinetic reasons, cannot be made if the intercalant vapor has to diffuse large distances into a pre-existing graphitic host. In particular, homogeneous oriented submicron films of either pure stage-3 (Se 24 C) or mixed-stage Se—carbon layer compounds have been successfully grown on Ni substrates in evacuated sealed quartz tubes. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and the c -axis electrical transport measurements are discussed in terms of both covalent Se—carbon bonding and an ionic model assuming the formation of an acceptor-type Se—GIC with electron transfer from carbon to Se. Our CVD-grown Se—carbon films exhibit the largest thermoelectric power reported in the open literature among carbon-based compounds. However, the value is at least a factor of 10 less than reported for these materials in patents by Sharp Corp.

CVD-Growth of Thin-Film Layered Se-Carbon Compounds

Oriented films of layered Se-carbon compounds are grown on Ni substrates in evacuated sealed quartz tubes. Results of X-ray diffraction, Raman scattering and the c-axis electrical transport studies are reported. A discussion of possible models for the carbon -Se interaction is presented.