Photoluminescence of Ce³⁺, Tb³⁺: Y₂O₃ nanoclusters embedded in SiO₂ sol-gel glasses

Ce³⁺ doped and Ce³⁺, Tb³⁺ codoped Y₂O₃ nanoclusters embedded in SiO₂ glasses were prepared by sol-gel method. Intensive photoluminescence with a strong blue band at 420 nm and a weaker band at 480 nm was observed from 1% Ce³⁺:10% Y₂O₃-SiO₂ samples, and strong green emission at 543 nm from Tb was obtained in 1% Ce³⁺, 1% Tb³⁺:10% Y₂O₃-SiO₂ samples. Excitation spectra reveal that the 5d state of Ce³⁺ covers UV range from 240 to 380 nm; energy transfer from 5d state of Ce³⁺ to Tb³⁺ is very efficient, and the absorption of Ce³⁺ in UV is the dominant energy source for the green emission of Tb³⁺.