Preparation, Design, and Characterization of the Novel Long Persistent Phosphors: Na2ZnGeO4 and Na2ZnGeO4:Mn2+

A novel blue-emitting phosphor Na2ZnGeO4 and a novel green-emitting phosphor Na2ZnGeO4:Mn2+ have been newly developed via high-temperature solid-state reaction. The crystal structure of Na2ZnGeO4 has been identified. Energy transfer from Na2ZnGeO4 host to Mn2+ ions was affirmed. Undoped and Mn2+-doped Na2ZnGeO4 phosphors exhibit blue and green long persistent luminescence (LPL) with persistent duration more than 40 min and 4 h, respectively. The traps created in host lattice were clarified. The LPL mechanism in Na2ZnGeO4 and Na2ZnGeO4: Mn2+ was discussed briefly. This investigation provides two new and efficient long persistent phosphors (LPPs).