Oxygen vacancies in amorphous silica: structure and distribution of properties

We used an ab initio embedded cluster method to study and compare three charged states of the Si-Si dimer configurations of oxygen vacancies in α-quartz and amorphous silica. The Si-Si bond in the neutral vacancy remains largely the same in both crystalline and amorphous SiO2. In α-quartz the positively charged dimer E′ centre exists only as a meta-stable configuration, whereas in amorphous silica stable dimer configuration can be formed at favorable precursor sites. Our results demonstrate that negatively charged dimer oxygen vacancies can be formed in α-quartz.