Structural Features of Pyrolytic Graphite

The structure of pyrolytic graphite has been examined on several samples deposited under various conditions at 1340 to 2310 degrees C and 5 to 200 torr by means of an X-ray technique. The structural features investigated include interlayer spacing, ordering, preferred orientation, intercrystallite porosity, and crystallite size. These features are closely related to the microstructure and density. In particular, the temperature dependence of crystallite size explains three types of formation mechanism, the cause of the occurrence of a minimum density at a certain temperature, and the cause of a preferred orientation in pyrolytic graphite.