LUMINESCENCE OF BaGa2Se4 CRYSTALS ACTIVATED BY Eu2+ and Ce3+ IONS

We have studied the effect of doping with Eu2+ and Ce3+ ions on the photoluminescence (PL) of BaGa2Se4 crystals in the temperature range 77-300 K. We have established that the broad bands with maxima at wavelengths 456 nm and 506 nm observed in the photoluminescence spectra of BaGa2Se4:Ce3+ crystals are due to intracenter transitions 5d --> F-2(7/2) and 5d --> F-2(5/2) of the Ce3+ ions, while the broad photoluminescence band with maximum at 521 nm in the spectrum of BaGa2Se4:Eu2+ is associated with 4f(6) 5d --> 4f(7) (S-8(7/2)) transitions of the Eu2+ ion. We show that in BaGa2Se4:Eu2+, Ce3+ crystals, excitation energy is transferred from the Ce3+ ions to the Eu2+ ions.