Structure and formation mechanism of the Eα′ center in amorphous SiO2

Abstract

We provide a possible formation mechanism for one of the Si-related paramagnetic centers in amorphous silica, Eα′, which is stable only below 200 K, on the basis of the quantum-chemical calculations. We show that the divalent Si defect can trap a hole, resulting in two different types of paramagnetic centers that are consistent with the experimental spectral features for Eα′. The highly anisotropic symmetry and the isotropic hyperfine coupling constants observed for one of the Eα′- center variants are reproduced by the present model.