Influence of the synthesis conditions on the photoluminescence of silica gels

Abstract

The photoluminescence spectra of silica xerogel samples synthesized with ethanol as solvent and xerogel where the ethanol was exchanged by water before drying are reported. In addition, the photoluminescence spectrum of a silica cryogel synthesized with tert-butanol as solvent was investigated. The samples were modified by formamide. Bands at 2.00, 2.20, 2.32 and 2.46 eV were identified. In the photoluminescence spectra of all samples. The band at 2.00 eV is caused by the presence of silane, and the band at 2.20 eV is connected with the nonstoichiometric composition of silica. The photoluminescence band at 2.32 eV was found to originate from the organic groups of the solvent. The origin of this band are E’ defect centers, which is a prominenet paramagnetic defect in conventional a – SiO2.

Keywords

• silica gel
• luminescence
• infrared spectroscopy