Fluorescence properties of valence-controlled Eu2+ and Mn2+ ions in aluminosilicate glasses

Controlling of valence states of metal ions doped in glasses has attracted considerable interest due to the possibility of looking toward optical applications. In this study, new Na2O-Al2O3-SiO2 glasses were developed to dope Eu2+ and Mn2+ with well controlled valence states by heating in H2 gas atmosphere, and the changes in the valence state of doped-ions and their fluorescence properties were investigated using visible and infrared optical absorption spectroscopies, X-ray absorption fine structure spectroscopy, and fluorescence spectroscopy. Among Eu3+, Mn3+ and Mn2+ ions incorporated in the as-prepared glasses, the Eu3+ and Mn3+ ions were reduced to Eu2+ and Mn2+ ions, respectively, by heating in H2 gas and OH bonds were concurrently formed. The fluorescence spectra of glasses heated in H2 exhibited broad emission bands at 450 and 630 nm wavelength, assigned to the Eu2+ and Mn2+, respectively, ions, in which the fluorescence intensity at 450 nm was observed to decrease with increasing Mn2+ ion content. The increased fluorescence intensities were analyzed as the energy transfer from Eu2+ to Mn2+ ions and the energy transfer efficiency was estimated with a concentration of Eu2+and Mn2+ ions.