Radiation Damage to the Electrical Conductivities of Natural Graphite Crystals

Abstract

When natural graphite crystals were exposed in nuclear reactors, it was found that the $a$-axis electrical conductivity decreased progressively and monotonically, eventually about twenty-fold. The $c$-axis electrical conductivity decreased by a factor of about three to a minimum and then slowly increased somewhat. Very early in the irradiation, the temperature dependence of the conductivities altered to a negligible dependence on temperature, indicating the spacing of fixed scattering centers in the original crystals was at least hundreds of atomic spacings. The approximate values of the crystallite conductivities in artificial graphite are inferred from the results obtained for the natural graphite crystals.