THERMOELECTRIC POWER OF GLASSY CARBON.

The thermoelectric power of glassy carbon, heat-treated for three hours between 1200 and 2700 degree C, has been measured at temperatures from 1. 5 to 280 K. The dependence of thermoelectric power S on temperature T can empirically be written as S equals aT plus bT** one-half plus S//B, where the first term is a strong-scattering metallic component, the second term is attributed to variable-range hopping and the third term is a peaked component. The constant a involves the sign of the carriers in the extended states; carriers change their sign from negative to positive at a heat-treatment temperature of about 1500 degree C as the heat-treatment temperature is increased. The constant b provides information on the density of states at the Fermi level for the localized states. The nature of S//B remains to be explored.