The persistent luminescence and up conversion photostimulated luminescence properties of nondoped Mg2SnO4 material

The nondoped Mg2SnO4 material with inverse spinel structure was synthesized by solid state reaction. This phosphor showed a broad green emission band covering 470-550 nm under 291 nm excitation, which was due to the recombination of F centers with holes. Stimulated by 980 nm infrared laser, the green photostimulated luminescence was first observed in a nondoped oxide. After ultraviolet irradiation, the green persistent luminescence of Mg2SnO4 could be seen in darkness for about 5 h. The decay curves revealed that the long persistent luminescence was governed by tunneling mechanism and it proved the presence of different trap clusters in Mg2SnO4. These trap clusters (such as [Sn-Mg(center dot center dot)-O-i ''], [Sn-Mg(center dot center dot)-2e'], and [Sn-Mg(center dot center dot)-e '']) induced the trap levels with different depths in band gap and corresponded to the three components (at 110, 168, and 213 degrees C) of the thermoluminescence glow curve of Mg2SnO4. These trap levels with different depths were proved to be not independent. It revealed that the shallow traps (110 degrees C) and part of the deep traps (168 and 213 degrees C) were involved in the persistent luminescence. Meanwhile, all the shallow and deep traps were responsible for the photostimulated luminescence. Accordingly, the photoluminescence, persistent, and photostimulated luminescence mechanisms of the nondoped Mg2SnO4 material were first proposed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3524280]