Transport mechanism of multivalent ions of transition metals into silicate glasses by solid-state field-assisted ion exchange

Abstract

Field-Assisted Solid-State Ion-Exchange (FASSIE) technique for doping silicate glasses with transition metals and rare-earths has been attracting much attention for its potential applications in light waveguides, luminescent materials and for the possibility to realize systems in which formation of metal nano-cluster is controlled by suitable postexchange techniques1-6. In the presented experiments, metallic films of Au and Co are deposited onto the soda-lime (SL) and borosilicate (BK7) substrates by the radiofrequency (rf) sputtering technique. Metal ions substitute the glass alkali by means of field-assisted diffusion realized at different values of temperature and electric field. Preliminary results are also presented for the direct diffusion of Er owing to the applied field. The nanocomposites are characterized by secondary ion mass spectrometry (SIMS), Rutherford backscattering spectrometry (RBS), optical absorption and transmission electron microscopy (TEM), indicating that the migration not only depends on the experimental parameters but also on the local structure and the chemical phenomena occurring at the metal/glass interface. The alkali composition in both glasses dramatically changes the diffusion profiles, resulting in a homogenous and uniform in-depth diffusion in BK7 glass than SL.