The isotope effect, ln(D)/ln(1/m), for Co diffusion in structurally relaxed glasses was measured by using a radiotracer technique. No isotope effect was detected to within experimental accuracy. It was suggested that this reflected the operation of a highly cooperative diffusion mechanism.

A.Heesemann, K.Rätzke, F.Faupel, J.Hoffmann, K.Heinemann: Europhysics Letters, 1995, 29[3], 221-6