Effect of FeCl₄^– intercalation on the transport properties of a graphitized polyimide film

The temperature variation of the thermal conductivity, the electrical resistivity, and the thermoelectric power of a graphitized polyimide film have been measured in the temperature range 2 < T < 300 K. The effect of the electrochemical intercalation with FeCl₄₋ ions has also been studied. The thermal conductivity measurements confirm the high degree of graphitization that may be obtained with polyimide films. They show how intercalation increases the structural disorder and how the intercalate substantially contributes to the thermal conductivity at low temperatures. The electrical-resistivity and thermoelectric-power measurements reveal that the density of free carriers is about three times lower in stage-2 FeCl₄₋ solvated intercalation compounds obtained by an electrochemical way than in stage-2 FeCl₃ compounds obtained by a classical synthesis method.