ELECTRICAL-TRANSPORT OF THE PYROLYZED MATERIALS - POLYACENIC AND POLYACRYLONITRILE

The electrical conductivity and thermoelectric power(TEP) of the prist ine pyrolyzed polyacrylonitrile(Pyro PAN) as well as the pristine and the FeCl3 doped polyacenic materials have been measured. The results f or Pyro PAN are somewhat complicated, which depend on the pyrolysis co nditions and aging time in the air after the pyrolysis. Some samples s how the nearly zero TEP value and the temperature independent TEP in a wide region of temperature is observed, which may indicate the strong ly correlated system. But the change of TEP in time sequence means tha t the system is metastable. The values of room temperature conductivit y vary from approximately 0.1 to 90 (S/cm), and the weak temperature d ependence monotonously decreasing upon cooling with sigma(30K)/sigma(2 90K)= 0.7 approximately 0.8 is observed. The conductivity measurement of the pyrolyzed polyacenic materials of T(p) = 500-degrees-C indicate s that the conduction mechanism of this material can be explained by t he variable range hopping model. And the conductivity of T(p) = 700-de grees-C sample indicates that it is much more carbonized.