The blue-light emission enhancement mechanism of Eu2+ in Eu, Dy: SiO2 matrix

A Eu, Dy co-doped SiO2 matrix xerogel with blue emission was prepared by the sol-gel method. Strong blue emission located between 425 nm and 525 nm with a peak at 486 nm is observed under UV laser excitation at room temperature, which is related to a 4f → 5d energy transition of Eu2+. Such techniques as FT-IR and TGA-DSC were used to measure the microstructure of the luminescent materials. The influence of Dy3+ ions on the luminescent property of Eu2+ was investigated. The emission intensity of Eu, Dy-codoped samples is stronger than that of Eu doped samples. The emission enhancement mechanism relating to Eu2+ is attributed to an energy transfer involving Dy3+ → Eu2+. Using energy transition theory, we speculate that the mechanism may be one of the resonance transfers via multi-polar interactions, and present a possible energy transfer model. The Eu2+ blue emission intensity reaches the maximum when the Dy3+ concentration is 0.1 mol%. When the concentration of Dy3+ is 0.3 mol%, a fluorescence quenching appears which might be related to the overlap part of Eu2+ excitation and emission levels, and also suggests the existence of Eu2+ → Eu2+ energy transfer.