Formation of metallic nanophases in silica by ion-beam mixing. Part I: Mixing mechanisms

The ion beam mixing of thin Ag layers embedded in a SiO₂ matrix is studied by means of the Rutherford backscattering technique. Two different mechanisms are observed: at low temperature (300 K and below) the variance of the mixed profile varies with the square of the ion fluence, whereas at higher temperature (400 K to 620 K) a linear variation is found. The low-temperature kinetics are accounted for by the migration of Ag-defect complexes after introduction of Ag atoms into the silica matrix by a ballistic process. A combination of ballistic and radiation-enhanced diffusion processes explains the results obtained at high temperature. This work emphasizes the role of the presence of metallic clusters on the migration of metal atoms in silica.