Fluorescence and phosphorescence properties of the low temperature forms of the MAl2Si2O8:Eu2+ (M=Ca, Sr, Ba) compounds

The fluorescence and phosphorescence properties of Europium-doped MAl2Si2O8 (M=Ca, Sr, Ba) are reinvestigated and discussed on the basis of the propensity of an activator to agglomerate with an oxygen vacancy. Due to a stronger attraction of the anion vacancy towards Eu2+ cations going from BaAl2Si2O8 to SrAl2Si2O8 and CaAl2Si2O8 host lattices, the interpretation of the fluorescence spectra turns out to be less trivial in the Ca and Sr host lattices than in the Ba one and requests the account for Eu2+ cations lying at alkaline-earth sites with or without vacancy in their neighborhood. Phosphorescence in these compounds is highlighted.