Electrical conductivity of low-temperature carbons as a function of frequency

The electrical conductivity of anthracene carbon samples, heat treated to temperatures of 600, 650, 730 and 800°C is measured at variable frequency up to 100 MHz. The carbons heat-treated to 600 and 650°C have a specific behaviour of amorphous solids, whereas the carbons HTT 730° and 800°C have an electrical conductivity independent of the frequency. The experimental results are correctly explained by means of the equations developed by Pollak and Geballe. Analysis of the results points to the conclusion that a hopping conduction between localized states could be a possible process of conduction in such solids.