An investigation was made of the penetration of O2- ions, into single crystals which were doped with 0.05mol%Sm, by making measurements of the depth of discoloration of the originally green crystals; as caused by the presence of O2- ions. It was concluded that the rate-limiting factor in the O penetration process was bulk diffusion, rather than a surface reaction. It was deduced that the activation energy for diffusion was equal to 45kcal/mol at temperatures ranging from 820 to 1000C.

Oxygen Penetration into CaF2:Sm2+ Crystals. K.Muto, K.Awazu: Journal of Physics and Chemistry of Solids, 1968, 29[7], 1269-73

Table 161

Diffusion of 88Kr from Neutron-Irradiated

U-Doped CaF2 Single Crystals