TIME-DEPENDENT ELECTRICAL-RESISTIVITY OF CARBON

Carbon material prepared via electrochemical reduction of poly(tetrafluoroethylene) by alkali-metal amalgam shows a time-dependent electrical resistivity. The gradual decrease of electrical resistivity follows well-defined kinetics on a time scale of at least 1 year. The rate of resistivity drop depends on the type of alkali metal used for reduction: it increases in the sequence K < Na < Li. Electronic conduction of the carbon thus prepared satisfies the electron-hopping model. The time development of conductivity is discussed in terms of structural changes of the carbon matrix and possible role of n-doping of the electrochemically prepared carbon. © 1990 American Chemical Society.