Rare-earth aggregates in sol-gel silica and their influence on optical properties

Radio-luminescence, time resolved photo-luminescence and Raman spectroscopy measurements were performed on Ce-doped sol-gel silica glasses. Quenching of the 5d-4f Ce3+ emission transition was observed by increasing Ce 3+ concentration above 0.04 mol%, evidenced by a decrease of the emission intensity accompanied by the appearance of a fast component in the photoluminescence time decay. Raman measurements revealed the formation of CeO2 clusters, which can be considered a cause of the observed luminescence quenching.