Autoradiography was used to obtain 14C concentration profiles in annealed 15mm spherical polycrystalline specimens with about 20% porosity in a CO2/N2 atmosphere. It was found that the results at 2270 to 2970C could be described by:

D (cm2/s) = 4 x 10-1exp[-45.8(kcal/mol)/RT]

Self-Diffusion of C. Golovina, E.S., Chaplygina, V.S., Kotova, L.L.: Doklady Akademii Nauk SSSR, 1969, 187[3], 558-61