Research On Luminescence Properties Of Anion Doped Silica-Based Materials

Silica has been widely used in the field of catalyzer carrier, medium material, and buffer layer for silicon-based photoelectronic materials due to its excellent chemical and thermal stability, as well as its good combination with silicon. Many studies on the optical property of silica have shown that there are many optic-active defect centers with excellent UV absorption and luminescence in silica. It is significant and important to further study the luminescence property and luminescence mechanism of silica-based materials modified with various cation and anion dopants.The nano-sized silica was synthesized by Sol-Gel method, and the luminescence properties of silica samples heat-treated at different temperatures and in different ambients were examined. It was found that there is a luminescence band at 344nm for the undoped silica sample after heat-treated at lower temperature. There are two luminescence bands at 385nm and 400nm respectively with a long tail toward the direction of long wavelength for the undoped silica sample heat-treated in H2 at hightemperature. On the base of stable preparation of nano-sized silica,Al³⁺ and Ce³⁺ cations were chemically doped into silica nanoparticles, and their optical absorption and luminescence properties were analyzed. The intensity of luminescence band at 383nm changed with the changing concentration of doping ions. The luminescent intensity increased with increasing concentration when the concentration of doping ions was low, but the intensity decreased and even disappeared with high doping concentrations.The excited 5d electron sits in the outer shell, and was much easy to be influenced by ligand fields. The Ce³⁺ ions doped silica samples were further decorated with S^2-and N^3- anions by controlled ambient methods. The decoration of those anions changed clearly the wavelength and intensity of luminescence. Especially the luminescence band of Al³⁺-Ce³⁺ doped silica decorated by N3- ion shifted from 383nm to 370nm and the intensity increased around 2 times.