ARTICLES Synthesis of vapor-grown carbon fibers from camphor without catalyst and their characterization

Vapor-grown carbon fibers and carbon micro-beads were produced in the absence of catalysts from a natural precursor, camphor, by a thermal chemical vapor deposition process, at different temperatures in an argon medium. Scanning and transmission electron microscopy, Raman spectra, and electrical conductivity studies were used to characterize these fibers. It was observed that cylindrical fibers (diameter ∼3 m) were obtained at 1033 K and rippled fibers (diameter ∼5 m) were formed at 1273 K while carbon beads (diameter ∼0.5-1 m) were formed at 1173 K. It is proposed that agglomeration of carbon beads predominate at pyrolysis temperature greater than 1173 K, resulting into rippled type fibers. I