EPR study of Ti3+ ions formed under beta irradiation in silicate glasses

Reduction processes of Ti4+ ions in various silicate glasses have been studied by EPR spectroscopy at 20 K. Different parameters like the [Na]/[Ti] ratio, the integrated dose and Ti3+ ions ageing processes were analyzed in this work. Simulation of the Ti3+ ion EPR spectra in different Ti-doped silicate glasses has shown three different Ti3+ environments attributed to one [VI]Ti3+ and two [V]Ti3+ environment (square pyramid and trigonal bi-pyramid). The [VI]Ti3+ ion environment is observed only for [Na]/[Ti] ratios higher or equal to 68 although the two others are observed for all values of the [Na]/[Ti] ratio considered. In terms of relative proportions, the Ti3+ ions in a square pyramid of oxygen are the dominant species.

Research Highlights
► Ti3+ ions formed under beta - irradiation were studied by EPR spectroscopy in silicate glasses.
► Three different Ti3+ EPR site were observed.
► The proportion of Ti3+ ions in each site depends on the [Na]/[Ti] ratio, on the total integrated dose and on the age of the sample.
► First EPR site is associated to [VI]Ti3+ and the two others to [V]Ti3+ (trigonal pyramid and square based pyramid geometries).