Ge‐doping dependence of gamma‐ray induced germanium lone pair centers in Ge‐doped silica

Abstract

We report an experimental study on the γ irradiation effects in Ge‐doped sol‐gel silica samples doped with Ge from 102 up to 104 part per million molar. The samples were exposed to the radiation generated by a 60Co source up to an accumulated dose value of 10 MGy. Our data evidence that the γ irradiation significantly increases the number of Germanium Lone Pair Centers (GLPC). Such defects are induced with a concentration that depends on the Ge content of the employed material in those samples where no optical activity related to GLPC was detected before irradiation. Furthermore an increase of the GLPC concentration was detected also in a sample that already contains this defect after the production. These findings show that, in addition to the GLPC bleaching effect already reported in the literature, γ rays can generate such defects and a range of doses exists in which the generation processes overcome the bleaching processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Formation of optically active oxygen deficient centers in Ge-doped SiO2 by γ- and β-ray irradiation

“…In addition to the generation and the growth of the paramagnetic Ge related point defects and of the associated optical absorption bands, we observed the generation and the growth of the GLPC also by b irradiation, in agreement with the findings after c-ray exposure [24,25]. In Fig.…”

“…In particular, the generation of Ge(1), E'Ge and H(II) has been considered. In addition to these types of point defects we investigate for the first time the generation of GLPC under b irradiation and we compare the results with those recently obtained by c irradiation [24,25].…”

“…Despite the wide and debated spectroscopic characterization of these defects, the mechanisms of their formation by ionizing radiation has been poorly understood. In particular, the recently found formation by irradiation of the GLPC has been investigated only by c-ray [24,25], and the extension to other sources has not been studied yet.…”