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 conditions 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 closely 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.