The influence of irradiation on the microhardness and photoluminescence of SiO2

The microhardness and photoluminescence spectra excited with 337-nm laser radiation in commercial SiO₂ glasses (UV windows, substrates with BaTiO₃ film coatings) exposed to ⁶⁰Co gamma radiation and a mixed neutron flux from the reactor are investigated. It is revealed that initial samples contain nanocrystalline phases. An increase in the microhardness and the intensity of the excitonic UV luminescence due to ⁶⁰Co gamma irradiation and the quenching of the photoluminescence associated with the nonbridging oxygen centers result from healing of Si-O dangling bonds and microcracks in the surface layer at the nanocrystal-glass matrix and substrate-coating interfaces. It is demonstrated that reactor irradiation leads to the phase transformation of SiO₂ cristobalite into tridymite and BaO into BO₂, as well as to the decomposition of BaTiO₃ and BaCO₃. This brings about a decrease in the microhardness and photoluminescence quenching.