Ge (2), Ge (1) and Ge-E′ centers in irradiated Ge-doped silica: a first-principles EPR study

L. Giacomazzi (1) , Layla Martin-Samos (2) , Aziz Boukenter (3) , Youcef Ouerdane (3) , Sylvain Girard (3) , Nicolas Richard (4)

1 CNR-IOM DEMOCRITOS
2 University of Nova Gorica
3 LHC - Laboratoire Hubert Curien
4 DAM/DIF - DAM Île-de-France

We present a first-principles investigation of Ge paramagnetic centers in Ge-doped vitreous silica (v-SiO2) based on calculations of the electron paramagnetic resonance (EPR) parameters. We infer, by analyzing g-values differences with respect to our Ge-E′ configurations, that the EPR signal of the Ge(2) center may arise from Ge forward-oriented (Ge-FO) configurations, where the unpaired spin is localized at a three-fold Ge atom featuring a weak bond with a three-fold O atom, ∼ 1.9 Å long. Moreover we show that two-fold Ge atoms, i.e. the germanium lone pair centers (GLPC), under irradiation can easily convert into Ge-FO configurations consistently with experimental observations.

Domaines: Matière Condensée [cond-mat]

L. Giacomazzi, Layla Martin-Samos, Aziz Boukenter, Youcef Ouerdane, Sylvain Girard, et al.. Ge (2), Ge (1) and Ge-E′ centers in irradiated Ge-doped silica: a first-principles EPR study. Optical Materials Express, 2015, 5 (5), pp.1054-1064. ⟨10.1364/OME.5.001054⟩. ⟨ujm-01185806⟩