Thermoelectric power of heat-treated CVD carbon fibers

Abstract We measured thermoelectric power (TEP) in the temperature range from 5 to 300 K for heat-treated carbon fibers prepared by chemical vapor deposition of cyanoacetylene on pitch-based carbon fibers. The thermoelectric power of the fiber heat-treated at 2,000°C is positive and exhibits almost monotonic temperature dependence above about 20 K. Thermoelectric power decreases with increasing heat-treatment temperature (HTT), which indicates the formation of graphite structure. TEP for fibers heat-treated over 3000°C have negative dips around 25 K that are ascribed to the phonon-drag effect. TEP for the fiber with 3300°C HTT shows an anomaly near 15 K in addition to the negative dip, suggesting the highly graphitized structure. TEP of the HNO 3 -intercalated graphite fiber (HTT; 3300°C) is also measured.