AC and microwave conductivity of PAN-based carbon fibers

Frequency dependence of conductivity (100 – 109 Hz) and microwave conductivity (9.4, 12.2, 16 GHz) have been measured at room temperature for PAN-based carbon fibers with different heat treatment temperature (HTT). All measurements have been made using a single filament. AC conductivity was increased by no more than 18% in the range of 0.5 Hz - 1.2 GHz. The fibers with HTT 1400°C - 1800°C show a peculiarity of microwave conductivity at 1010 Hz while the microwave conductivity of the fibers with HTT > 1800°C did not exceed their DC conductivity. These data are discussed in view of contemporary models of charge transport in a nonuniform solid state.