On the stabilization of Ce, Tb, and Eu ions with different oxidation states in silica-based glasses

Abstract We investigated the influence of the silica-based glass composition and its synthesis conditions on the oxidation states of luminescent rare earths like Ce, Tb, and Eu dopant ions. It was found that the repeated melting of the glass led to the stabilization of rare-earth ions in higher oxidation states; in the case of Ce doping, this caused a significant decrease in the scintillation yield, whereas for Tb doping no significant modifications were noticed. Furthermore, it was concluded that the glass matrix influences the rare-earth oxidation state depending on the ions modifying the glass structure. This effect was clearly observed for the Eu-doped series of Ca, Sr and Ba di-silicate glasses, where the conversion of Eu 3+ to Eu 2+ was found to be dependent on the distortion of the silica network. The influence of glass crystallization on the rare-earth oxidation state stabilization is also discussed.