Effect of oxygen deficiency on the radiation sensitivity of sol-gel Ge-doped amorphous SiO2 |
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Authors: | S Agnello A Alessi F M Gelardi R Boscaino A Parlato S Grandi A Magistris |
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Institution: | (1) Department of Physical and Astronomical Sciences, University of Palermo, via Archirafi 36, 90123 Palermo, Italy;(2) Department of Nuclear Engineering, University of Palermo, Viale delle Scienze, Building 6, 90128 Palermo, Italy;(3) Department of Physical Chemistry, University of Pavia, via Taramelli 16, 27100 Pavia, Italy |
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Abstract: | We report experimental investigation by electron paramagnetic resonance (EPR) measurements of room temperature γ-ray irradiation
effects in sol-gel Ge doped amorphous SiO2. We used materials with Ge content from 10 up to 104 part per million (ppm) mol obtained with different preparations. These latter gave rise to samples characterized by different
extents of oxygen deficiency, estimated from the absorption band at ~5.15 eV of the Ge oxygen deficient centers (GeODC(II)).
The irradiation at doses up to ~400 kGy induces the E'-Ge, Ge(1) and Ge(2) paramagnetic centers around g ~ 2 with concentrations
depending on Ge and on GeODC(II) content. We found correlation between Ge(2) and GeODC(II) contents, supporting the suggestion
that the latter defect is the precursor of Ge(2). Even if the concentration of E'-Ge and Ge(1) defects cannot be strictly
related to GeODC(II) one, the concentration growth of these paramagnetic defects with irradiation evidences that the radiation
sensitivity is enhanced by the oxygen deficiency for Ge doping above 1000 ppm mol and it is reduced below 100 ppm mol. Moreover,
the investigation of samples with different GeODC(II) concentration but fixed Ge content has shown that the oxygen deficiency
enhances the overall radiation sensitivity for GeODC(II)]/Ge] in the range 10-3
10-2. |
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Keywords: | 61 72 Hh Indirect evidence of dislocations and other defects (resistivity slip creep strains internal friction EPR NMR etc ) 61 80 Ed Gamma-ray effects 71 55 Jv Disordered structures amorphous and glassy solids |
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