Diamagnetism of Dilute Acceptor Compounds of Graphite

Diamagnetism study on graphite-acceptor compounds has been further extended over dilute nitrates and slightly neutron-irradiated graphite. An analysis was made on the basis of Sharma-Johnson-McClure's theory taking into account the trigonal warping of the Fermi surface. The susceptibility vs reciprocal termperature plots, including those for IC l compounds not completely interpreted in the previous study, have been theoretically reproduced by assuming a mixed phase structure of orderly intercalated and purely graphitic domains in each sample. The hole production rate (ionization efficiency) of acceptors was evaluated by using Ono-Sugihara's formulae which take into account the trigonal warping effect on the carrier density. It has been found that 5% of intercalated IC l is ionized in the doped regions irrespectively of the total content.