Luminescent properties of a green long persistent phosphor Li_2MgGeO_4:Mn^2+

A novel rare-earth ion free phosphor, Mn2+-activated Li2MgGeO4, was prepared by a high temperature solid-state reaction method. The phase structure was identified by XRD. We reported on its photoluminescence and long persistent luminescence properties. The green emission with a broad band centered at 525 nm corresponds to the 4T1(4G)–6A1(6S) transition of the Mn2+ ions. After irradiation by 254 nm UV light, green long persistent luminescence can be observed and last at least 5 h. Thermoluminescence was studied and the long persistent luminescence mechanism was also discussed in detail.