Synthesis and luminescence properties of a novel deep red phosphor Li2ZnTi3O8:Mn4+ for plant-cultivation.

In this thesis, a novel ultraviolet-activated Li2ZnTi3O8:Mn4+ red emitting phosphor is prepared by the traditional high-temperature solid-state reaction method in air. The crystal structure, luminescence properties and decay curves of the phosphor are studied in detail. The sample belongs to spinel cubic crystal structure and there are abundant [TiO6]8- octahedron sites can be occupied by Mn4+. The Li2ZnTi3O8:Mn4+ phosphor shows the red emission in region of 600-800 nm with a maximum at ~681 nm under 330 nm excitation, which can promote the plant growth. The optimal Mn4+ doping concentration is ~0.3 mol%, which is higher than that of other hosts. By calculating the crystal field strength (Dq) and Racah parameter B, we can evaluate that there is a strong crystal environment of Mn4+ in the Li2ZnTi3O8 host lattice, which major comes from the 2Eg → 4A2g transition of Mn4+ ion. Furthermore, the characteristics of thermal quenching are also studied, poor thermal quenching performance may be due to high doping concentration of Mn4+. All data suggest that Li2ZnTi3O8:Mn4+ phosphor can be a potential application in plant-cultivation.