Enhanced diffusion of solute metals forming complexes with radiation defects in silica

The mixing kinetics of Cu, Ag, W, Pt, and Au single layers embedded in silica when irradiated with heavy ions at temperatures (T) of 110 and 300 K was investigated by means of in situ RBS analyses in alternation with irradiations. The spreading of peaks related to the metallic species is generally anisotropic and obeys either a quadratic or a linear dependence on the ion dose according to the increasing T. The quadratic law is attributed to a control of the diffusion by the coupling of the large impurity atoms M with matrix defects, and a classical regime of radiation enhanced diffusion is observed when this coupling is made easier (higher T or mass of M). Other factors such as internal stresses affect the rates of M dissolution and diffusion.