Dependence of the luminescence properties of submicron silica particles on manufacturing conditions

We investigated luminescence properties of submicron-sized silica particles prepared by Stöber method under different conditions. After annealing in a non-oxidizing atmosphere, the submicron-sized silica particles show a broad photoluminescence (PL) band at 500 nm ranging from visible to ultraviolet wavelength by excitation at 250 nm, and the one at 600 nm by excitation at 488 nm. The particle diameters were controlled by the ethanol contents or temperatures during synthesis. With decreasing particle diameters, the PL band appears by shorter annealing time. The PL was enhanced by the removal of impurities and subsequent formation of luminescent structures by the thermal annealing.