Luminescence properties of Eu2+ doped dibarium magnesium disilicate, Ba2MgSi2O7:Eu2+

A new persistent luminescence material, monoclinic Ba2MgSi2O7:EU2+ was prepared by a solid state reaction. Both the UV excited and persistent luminescence are observed at the green region centred at 505 nm. Both luminescence phenomena are due to the same EU2+ ion occupying the single Ba2+ site in the lattice. The R3+ co-doping (R is rare earth) usually enhances the persistent luminescence of Ba2MgSi2O7:Eu2-. Especially, the Tm3+ ion has a very strong effect. Two thermoluminescence peaks at 90 and 130 degrees C are observed in the glow curve of Ba2MgSi2O7:Eu2+, which is nearly ideal for a persistent luminescence material. The persistent luminescence is probably due to lattice defects i.e. oxygen (cation) vacancies, which create trapping levels for electrons (holes). Recombination of the electron-hole pair and energy transfer to the Eu2+ ion complete the probable persistent luminescence mechanism. The details of the mechanism(s) need, however, more experimental work to be carried out. The stable disilicate materials are very good candidates for the persistent luminescence materials as alternatives to the Eu2+ doped alkaline earth aluminates.