ABSTRACT
Silicon dioxide (SiO2) is an important optical material with excellent transparency from nearinfrared to vacuum-ultraviolet (VUV, ≲190 nm) spectral range, good chemical stability and radiation hardness, and high mechanical strength. These useful properties of SiO2 arise mainly from the strong Si-O bonds and absence of other weaker bonds, which are present in multicomponent silicate glasses. Among various polymorphs of SiO2, α-quartz, a crystalline polymorph of SiO2, and amorphous silicon dioxide (a-SiO2) are the most used optical materials, because they are commercially available in large sizes and with low impurity contents. However, such high-purity SiO2 often contains intrinsic point defects, characterized by “wrong” bonds other than the regular Si-O bonds. They are formed during manufacturing processes as well as by photolysis or radiolysis and signicantly inuence the optical properties of SiO2. Thus, investigation of properties and formation mechanisms of the intrinsic point defects is very important in obtaining SiO2 with good transparency and radiation hardness. Structure and properties of the intrinsic point defects in SiO2 are summarized in Devine (1988), Pacchioni et al. (2000), Griscom (1991), and Skuja et al. (1998a, 2001).
