The interdiffusion of Ni2+ and Mg2+ ions in solid solutions of the form, Ni1-xMgxFe2O4, was studied at temperatures ranging from 1470 to 1580K. The interdiffusivity was measured by using a couple method and electron-probe X-ray spectroscopy. It was found that, within the above temperature range, the interdiffusion coefficient of the cations could be described by the expressions:

x = 0.6:     D (cm2/s) = 820 exp[-379.6/RT]

x = 0.4:     D (cm2/s) = 89000 exp[-441.2/RT]

x = 0.2:     D (cm2/s) = 41000 exp[-436.2/RT]

Thus, the concentration dependence of the interdiffusion coefficient exhibited a maximum at 35 to 50mol%NiFe2O4. This maximum was attributed to the effect of a minimum in the melting curve of the system, and to a positive deviation of the solution from ideality. A displacement of the original boundary of the ferrite couple was attributed to a change in the parameter of the solid solution which was formed.

L.A.Bashkirov, A.V.Zubets, V.V.Pankov, M.G.Bashkirova, O.I.Pashkovskii: Izvestiya Akademii Nauk SSSR - Neorganicheskie Materialy, 1988, 24[10], 1700-3. (Inorganic Materials, 1988, 24[10], 1453-6)