Structural changes in SiO2 and TiO2 gel films were investigated using ultraviolet (UV) and vacuum ultraviolet (VUV) irradiations. A significant compaction with dehydration of SiO2 gel films was induced by irradiation of photons in the range of 9-18 eV. The refractive index and the shrinkage of the irradiated SiO2 gel films were comparable to those obtained by sintering at 1000°C. Densification of TiO2 gel films was also observed with irradiation of 5-14 eV photons. However, effects of the irradiation on TiO2 gel were smaller that those on SiO2 gel. The structural changes in the gel films are attributed to electronic excitations which are induced by irradiation with photons having higher energies than the bandgap of the oxides. The photo-induced effects are presumed to depend on the optical properties and structure of the gels.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry