White light emission from transparent SiO2 glass prepared from nanometer-sized silica particles

We report that nanometer-sized silicon-dioxide particles are sintered to optical transparency at temperatures even below 1000°C, forming nonporous bulk silica glass. The resultant silica glass exhibits visible emission, which appears white to the naked eye, in the wavelength range from ∼400to∼700nm at room temperature under ultraviolet excitation. The observed emission is quite stable after prolonged exposure to the atmosphere and shows no appreciable light-induced degradation. The present photoluminescence characteristics are found to be basically different from those reported previously for silica nanoparticles and silica-based porous materials.