The diffusion coefficients were measured in Mg-Si-Al-O-N glasses which had compositions that were similar to those which were present at the grain boundaries of dense Si3N4 ceramics. They were determined, at temperatures ranging from 690 to 920C, by measuring the concentration profiles of 22Na and 59Fe radiotracers, using residual activity methods. The atomic ratio of Al:Mg:Si in the glasses was maintained constant at 1:1.36:2.32. It was found that the Na and Fe diffusivities at 800C increased from 3.96 x 10-13 to 6.08 x 10-12cm2/s and from 2.70 x 10-14 to 1.02 x 10-13cm2/s, respectively, as the N concentration in the glass was decreased to zero from its highest value (8.56at%). The activation energies for Na and Fe diffusion were 42.68 and 29.92kcal/mol, respectively, for a glass which contained 8.56at%N. These values were larger than those which were found for N-free glass. Both diffusion processes were governed by the interstitial mechanism.

T.Das, A.S.Sanyal, J.Mukerji: Physics and Chemistry of Glasses, 1994, 35[5], 198-201