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Electrical resistivity of iron intercalated graphitized carbon fibers
Synthetic Metals, 3 (1981) 149
149
© Elsevier Sequoia S.A., Lausanne -- Printed in the Netherlands
ELECTRICAL RESISTIVITY OF IRON INTERCALATED GRAPHITIZED CARBON FIBERS
D. J. GILLESPIE, A. C. EHRLICH and P. F. WATERS U.S. Naval Research Laboratory, Washington, DC 20375 (U.S.A.)
The electrical resistivity of five different graphitized carbon fibers manufactured from a variety of precursers, and using a range of heat treatment temperatures (HTT) ranging from 1500 to 3000 °C, has been measured from 2 to 300 K both before and after intercalation with iron. The importance of strain-free fiber mounting procedures for temperature dependent studies was manifested and a strain-free sample mounting procedure developed. Prior to intercalation the various fibers show a wide range of both temperature dependent and room temperature resistivities. The room temperature values are systematic with the HTT used during manufacture of the fiber and range approximately from 1700 u~2 cm for an HTT of 1500 °C to 170 g ~ cm for HTT of 3000 °C. The temperature dependent resistivities as measured by p (2 K) - p (300 K) show no such consistency in their magnitudes but are less variable from fiber to fiber. The values for p (2 K) - p (300 K) range from 100 g~2 cm to 300 p~2 cm. All fibers have an increasing resistivity with decreasing temperature starting from room temperature, but one fiber manifests a resistivity peak around 25 K. The iron intercalation was achieved by reacting the fibers with potassium vapor at 350 °C to form Cs K and then immersing the latter, at room temperature, in a solution of anhydrous ferric chloride in tetrahydrofuran. Intercalation with iron generally reduces both the room temperature- and the magnitude of the temperature dependent electrical resistivity. In general, the intercalated fibers do n o t show typical metallic resistivities.
149
© Elsevier Sequoia S.A., Lausanne -- Printed in the Netherlands
ELECTRICAL RESISTIVITY OF IRON INTERCALATED GRAPHITIZED CARBON FIBERS
D. J. GILLESPIE, A. C. EHRLICH and P. F. WATERS U.S. Naval Research Laboratory, Washington, DC 20375 (U.S.A.)
The electrical resistivity of five different graphitized carbon fibers manufactured from a variety of precursers, and using a range of heat treatment temperatures (HTT) ranging from 1500 to 3000 °C, has been measured from 2 to 300 K both before and after intercalation with iron. The importance of strain-free fiber mounting procedures for temperature dependent studies was manifested and a strain-free sample mounting procedure developed. Prior to intercalation the various fibers show a wide range of both temperature dependent and room temperature resistivities. The room temperature values are systematic with the HTT used during manufacture of the fiber and range approximately from 1700 u~2 cm for an HTT of 1500 °C to 170 g ~ cm for HTT of 3000 °C. The temperature dependent resistivities as measured by p (2 K) - p (300 K) show no such consistency in their magnitudes but are less variable from fiber to fiber. The values for p (2 K) - p (300 K) range from 100 g~2 cm to 300 p~2 cm. All fibers have an increasing resistivity with decreasing temperature starting from room temperature, but one fiber manifests a resistivity peak around 25 K. The iron intercalation was achieved by reacting the fibers with potassium vapor at 350 °C to form Cs K and then immersing the latter, at room temperature, in a solution of anhydrous ferric chloride in tetrahydrofuran. Intercalation with iron generally reduces both the room temperature- and the magnitude of the temperature dependent electrical resistivity. In general, the intercalated fibers do n o t show typical metallic resistivities.