Nanostructures formed in pure quartz glass under irradiation in the reactor core

• Сristobalite and tridymite nanocrystals grow in SiO2 glass at neutron irradiation.
• Oxygen vacancies and non-bridging atoms are accumulated in the nanocrystal shell.
• Splitting of absorption bands is due to formation of nanocrystal–glass interfaces.

Optical spectroscopy and X-ray diffraction techniques were used for studying nanoscale particles grown in pure SiO2 glass under irradiation with fast neutron fluencies within 6×1016–5·1019 cm−2 and gamma-quanta ~1.8×1020 cm−2 in the reactor core in water. The neutron irradiation results in destroying of the initial α- and β-quartz mesoscopic order of 1.7 and 1.2 nm sizes and growing of cristobalite and tridymite nanocrystals of 16 and 8 nm sizes in the thermal peaks of displacements reapectively. The point defects (oxygen deficient E′s, E'1, E'2 and non-bridging oxygen centers) induced by the γ-irradiation are accumulated in the nanocrystals shell of 0.65–0.85 nm thickness. Interaction of close point defects at the nanocrystal–glass interface causes the splitting of optical absorption bands into the intensive (D~2–4) resonances characteristic for local interband electron transitions, having the width of 10–15 nm close to the nanocrystals' sizes and the energy depending on their structure.