Measurements were made of the isotope effect for Co diffusion in the glassy and supercooled liquid states of a Pd40Cu30Ni10P20 glass. The isotope effect was very small (< 0.1) in both states; thus suggesting the occurrence of diffusion via highly collective hopping. In particular, the isotope effect did not change during isothermal relaxation from the glassy state to the supercooled liquid state. The results strongly supported the view that, even after macroscopic softening of a glass, the underlying atomic transport mechanism was still solid-like thermally activated hopping at temperatures considerably above the glass transition temperature.

Evidence of Diffusion via Collective Hopping in Metallic Supercooled Liquids and Glasses. V.Zöllmer, K.Rätzke, F.Faupel, A.Rehmet, U.Geyer: Physical Review B, 2002, 65[22], 220201 (3pp)