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The microhardness and photoluminescence spectra excited with 337-nm laser radiation in commercial SiO 2 glasses (UV windows, substrates with BaTiO 3 film coatings) exposed to 60 Co 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 60 Co 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 SiO 2 cristobalite into tridymite and BaO into BO 2 , as well as to the decomposition of BaTiO 3 and BaCO 3 . This brings about a decrease in the microhardness and photoluminescence quenching.