The migration of 32P in single crystals of α-phase material was studied at 599 to 850C. The P diffusivity was about 5 orders of magnitude higher than the self-diffusivity. The diffusivity perpendicular to the c-axis was larger than that parallel to the c-axis. The P diffusivity perpendicular to, and parallel to, the c-axis at 700 to 850C could be described by:

perpendicular:     D (cm2/s) = 1.55 x 10-1 exp[-32.9(kcal/mol)/RT]

parallel:     D (cm2/s) = 4.70 x 100 exp[-41.0(kcal/mol)/RT]

A marked downward curvature of the Arrhenius plot was found below 700C.

H.Nakajima, J.Nakazawa, Y.Minonishi, M.Koiwa: Philosophical Magazine A, 1986, 53[3], 427-37