Thermal stability and optical property of ormocers (organically modified ceramics) nanoparticles produced from copolymerization between amino-silanes and tetraethoxysilane

The effect of heat treatment on the optical activity of ormocers (aminopropyl-modified silica) is studied using photoluminescence and ultraviolet diffuse reflectance spectroscopy techniques. The thermal stability of the modified silica is also investigated by X-ray diffraction and thermogravimetric analyses. Great withstanding of aminopropyl group located inside the silica network is found at high temperature. Distinct blue and green bands are observed in the modified silica nanoparticles after heat treatment using different temperatures, whereas some optical activities in the area of near-ultraviolet and infrared relating to the OH-related and carbon-related species and non-bridging oxygen hole center, respectively, diminished. The decrease in the band intensity besides band shift was evidences for changing the structural defect owing to releasing and decomposing of aminopropyl group from the nanoparticle surface. Some ultraviolet bands were detected because of the existence of oxygen-related defect.