Layer-by-layer radiometric analyses, using 54Mn2+ tracers at 750 to 1050C, were carried out on essentially non-porous material with a grain size of more than 0.001mm. The resultant effective diffusion coefficients at 900C ranged from 2.8 x 10-11 to 2.0 x 10-9cm2/s, and could be described by

D (cm2/s) = 6.6 x 10-1 exp[-214(kJ/mol)/RT]

It was concluded that the diffusion parameters of the impurity depended upon the radius and its electric polarization. However, it seemed that these factors were insufficient to account for observed differences in diffusivities.

M.V.Slinkina, G.I.Dontsov, A.G.Segalla: Izvestiya Akademii Nauk SSSR - Neorganicheskie Materialy, 1991, 27[9], 1997-9. (Inorganic Materials, 1991, 27[9], 1696-8)