Structural properties of the range-II- and range-III order in amorphous-SiO<Subscript>2</Subscript> probed by electron paramagnetic resonance and Raman spectroscopy

In the present work we report an experimental investigation by electron paramagnetic resonance spectroscopy on the hyperfine structure of the E'<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$_\gamma$</EquationSource> </InlineEquation> point defect, probing the local arrangement of the network (range-II order), and by Raman spectroscopy on the D<Subscript>1</Subscript> and D<Subscript>2</Subscript> lines, probing mean features of the network (range-III order). Our studies, performed on a-SiO<Subscript>2</Subscript> samples thermally treated at 1000 °C in air for different time durations, show that changes of the hyperfine structure and of the D<Subscript>1</Subscript> and D<Subscript>2</Subscript> lines occur in a correlated way. These results give strong evidence that the range-II and range-III order properties are intimately related to each other and that these properties are determined by the history of the material. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2010