Synthesis and long-period phosphorescence of ZnGa2O4:Mn2+ spinel

Novel long-period phosphor ZnGa2O4:Mn2+ was prepared by a conventional solid reaction of ZnO, Ga2O3 and Mn(NO3)2 under condition of > 1000°C for 24 h in flowing Ar gas. The phosphor had green intense emission peaking at 503.6 nm. The improvement of emission intensity was brought out by the higher temperature processing. This implied that long lifetime phosphorescence was closel related to the formation of vacancies at the Zn2+ sites of the host lattice. The carrier trap level was positioned at 0.71 eV higher than the valence band of host lattice. The possible mechanism for prolonging the emission for a long time was discussed.