Layer-by-layer radiometric analyses, using 63Ni2+ 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) = 7.4 x 104 exp[-350(kJ/mol)/RT]

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)