Tracer diffusion measurements were performed, in vacuum and under high hydrostatic pressures, using amorphous samples. A marked structural relaxation

effect was observed, and led to a decrease in the diffusivity with annealing time. For well-relaxed samples, the results could be described by:

D (m2/s) = 1.9 x 10-9 exp[-1.65(eV)/kT]

The activation volume was equal to 0.51 atomic volumes.

Y.Loirat, J.L.Bocquet, Y.Limoge: Journal of Non-Crystalline Solids, 2000, 265[3], 252-64