Study of formation and sequential relaxation of paramagnetic point defects in electron-irradiated Na-aluminosilicate glasses: Influence of Yb

Abstract : Paramagnetic defects in electron irradiated Yb-doped Na-aluminosilicate glasses were studied. In particular, we paid more attention to characterize the defects with Electron Paramagnetic Resonance in links with the glass structure which was analyzed by Raman spectroscopy and Magic Angle Spinning Nuclear Magnetic Resonance. Under e(-)-irradiation hole centers on non-bridging oxygens bonded to Si with close presence of Na+, peroxy radicals, hole centers on oxygens bonded to Al (Al-OHC) and E' centers were detected. Doping glasses with Yb gives rise to more Al-OHC defects. Formations of hole centers and Al-OHC defects as well as their sequential relaxation are linearly anticorrelated. After the end of irradiation, the total amount of paramagnetic defects decreases in 2 months and then remains stable. The relaxation curve presents 2 regions with different rates of defect recovery. We showed in particular that the presence of Yb-clusters in the glasses acts on the relaxation of paramagnetic point defects by decreasing significantly the recovery of defects. (C) 2013 Elsevier B.V. All rights reserved.