The self-diffusion coefficient of calcium in single crystals of calcium oxide was measured at 1465 to 1760C using vapor-deposited thin films of radioactive Ca45O and boundary conditions for diffusion from a plane source into a semi-infinite medium. The temperature dependence of the diffusivity was expressed as:

D(cm2/s) = 11.25 x 10-5 exp[-64300/RT]

V.Kumar, Y.P.Gupta: Journal of Physics and Chemistry of Solids, 1969, 30[3], 677-85