Structure of brominated thornel P-100 carbon fibers

Brominated Thornel P-100 carbon fibers are found to be intercalated, as shown by Raman scattering. X-ray diffraction and electron diffraction show that the bromine layers in the fibers are disordered at room temperature, even though all previously reported graphite-bromine phases exhibit inplane superlattice ordering at room temperature. A new phase transition at 271 K was observed by differential scanning calorimetry, electron diffraction, and the variation of the electrical resistivity with temperature; it corresponds to the reversible change between inplane disorder above 271 K to inplane superlattice order below 271 K. The 240 cm^-1 intercalate Raman peak at room temperature is much broader than that of previously reported graphite-bromine, indicating more nonuniformity in intercalate structure in the fibers. The chemical interaction between bromine and the fibers is similar to that between bromine and graphite, as shown by the increase of the bromine desorption rate at 100°C upon heating for both fibers and graphite and the decrease of the electrical resistivity by bromination in fibers as well as graphite. No evidence for bulk bromine in the fibers was obtained.