Abstract
Changes in the a-axis and the c-axis thermal resistivity of pyrolytic graphite caused by electron irradiation at 82 K and by subsequent isochronal pulse annealing have been measured. The additive thermal resistivity at 78.5 K increases as 9.6×102N0.85f and (7.9±0.6)×103N0.75f cm deg/W in the a-axis and the c-axis directions, respectively, in the region of 2 ppm<Nf<70 ppm, where Nf is the concentration of nearly isolated Frenkel defects produced by irradiation. Annealing of the additive thermal resistivity occurs around 100 K and above about 220 K. The characteristics of annealing stages are different in some important respects from those obtained by Goggin and Reynolds. It is inferred that most interstitials do not recombine with vacancies below about 220 K.