Structural and transport properties of bromine intercalated carbon fibers

Intercalation of P-120 pitch-based fibers with bromine, from the vapor phase or liquid bromine, has been investigated. The maximum weight uptake was 20-25%, nearly independent of intercalation temperature. Intercalated samples were characterized by X-ray diffraction, Raman scattering and differential scanning calorimetry. Thermogravimetry experiments showed that a large amount (up to 50%) of bromine remains trapped in the fibers up to temperatures in the order of 1000 °C. Measurements of the transport properties (electrical conductivity, magnetoresistance and Hall coefficient) gave estimates of the concentration and mobilities of the charge carriers and of the charge transfer from carbon to bromine (0.5-0.6 electronic charge per Br₂).