Field-assisted diffusion behavior of transition metal ions in silicate glasses

Exact modeling of the field assisted solid state ion diffusion is lacking due to insufficient experimental data and understanding of the involved mechanism. In this study, the diffusion behavior of transition metal (Au, Ag/Cr) ions in sodalime silicate, borosilicate and pure silica glasses was investigated in an applied electric field with increasing temperature. The observed typical two-peak response gave an insight into the phenomena occurring at the metal-glass interface and demonstrated the dependence of diffusion on the nature of dopant, host matrix and experimental parameters. The secondary ion mass spectrometry confirmed the level of diffusion of the dopant into the glass while UV-VIS spectroscopy confirmed that the incorporated dopants were in non-precipitated state. Absorption spectra revealed precipitation of Cr nanoparticles, corresponding to the two oxidation states (Cr3 + and Cr6 +) in the annealed sodalime silicate glass. A modified lognormal distribution function was employed in non-linear fitting of the two-peak current versus time profile for possible deduction of diffusion and concentration coefficients of the host and dopant ions for extending the understanding of diffusion behavior.