LUMINESCENCE OF EU2+ IN BARIUM AND STRONTIUM ALUMINATE AND GALLATE

The luminescence of EU(2+), alkaline earth aluminates and gallates of the type Ba1-xSrx-Al2-yGayO4 (x = 0, 0.5, 1 and y = 0, 1, 2) has been studied. In both BaAl2O4:Eu2+ and SrAl2O4: EU(2+), green EU(2+) luminescence is observed from Eu2+ on the two different alkaline earth sites present in the lattice. The EU(2+) luminescence is at low energies due to preferential orientation of a d orbital of EU(2+) on the barium or strontium sites in these lattices. Due to photoionization, no EU(2+) luminescence can be observed in BaGa2O4:Eu2+ and SrGa2O4:Eu2+. When part of the gallium is replaced by aluminum, the characteristic EU(2+) luminescence as seen in BaAl2O4:Eu2+ and SrAl2O4:EU(2+) is again observed.