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The interdiffusion coefficients (D) of Na+, Ag+, K+, Rb* and Τl+ in pure f. c. c. Li2SO4 have been measured between 590 and 820 °C. D and the Arrhenius’ activation energies decrease in the same order as the ionic radii increase. D is a function both of the masses and the radii of the impurity cations. The results show that the Na+ and Ag* ions mainly diffuse in the sulphate lattice with the same mechanism as the lithium ions, while the larger ions are mobile in defects in the lattice. The Li*, Na+ and Ag* ions are probably diffusing between octahedral positions.

The diffusion coefficients of the divalent ions Mg, Zn, Ca, Cd and Pb have been measured between 600 and 800°C. The results can be described by an Arrhenius equation, where the preexponential factors decreases when the radius of the diffusing ion increases. By comparing results for univalent and divalent ions we have found that the formation energy is constant and that the migration energy decreases when the cation radius increases.