Diffusion process of metals in silica during ion irradiation

The mixing mechanism of thin layers of Au, Pt or W embedded in silica when irradiated with 4.5 MeV Au ions was studied as a function of the ion fluence φ, temperature T and layer thickness d. Analysis of the diffusion process by means of Rutherford backscattering spectrometry showed that the spreading of metal peaks was anisotropic and that their variance varied as φ at room temperature or φ² at 100 K. This behavior is attributed to an association of metal atoms with diffusing defects.