Nanocrystalline SnO2 Particles and Twofold-coordinated Sn Defect Centers in Sol-gel-derived SnO2–SiO2 Glasses

Abstract

Semiconductive nanocrystals of stannic oxide (SnO2) were precipitated in silica (SiO2) glasses synthesized via a sol-gel route. Kayanuma's equation, which describes the quantum confinement of an electron–hole pair in a semiconductive particle, well explained the absorption-edge shift due to the SnO2 nanocrystals in the optical absorption spectra. The adequate anneal of the SnO2–SiO2 glass ceramics in H2 gas led to the decomposition of the SnO2 nanocrystals and concurrently the production of twofold-coordinated tin atoms (Sn20 ) that provided a violet photoluminescence. The thermal behavior was studied with the x-ray diffraction measurement and photoluminescence and photoluminescence excitation spectroscopy.