Author:
Fung A.W.P.,Rao A.M.,Kuriyama K.,Dresselhaus M.S.,Dresselhaus G.,Endo M.,Shindo N.
Abstract
Because of their unusually large specific surface area (SSA), Activated Carbon Fibers (ACF's) have a huge density of micropores and defects. The Raman scattering technique and low-temperature dc electrical conductivity measurements were used as characterization tools to study the disorder in ACF's with SSA ranging from 1000 m2/g to 3000 m2/g. Two peaks were observed in every Raman spectrum for ACF's and they could be identified with the disorder-induced peak near ∼1360 cm−1 and the Breit–Wigner–Fano peak near ∼1610 cm−1 associated with the Raman-active E2g2 mode of graphite. The graphitic nature of the ACF's is shown by the presence of a well-defined graphitic structure with La values of 20–30 Å. We observed that the Raman scattering showed more sensitivity to the precursor materials than to the SSA of the ACF's. From 4 K to room temperature, the dc electrical resistivity in ACF's is observed to follow the exp [(T0/T)1/2] functional form and it can be accounted for by a charge-energy-limited tunneling conduction mechanism. Coulomb-gap conduction and n-dimensional (n ≤ 3) variable-range hopping conduction models were also considered but they were found to give unphysical values for their parameters.
Publisher
Springer Science and Business Media LLC
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Cited by
49 articles.
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