Synthesis, structure and luminescence properties of novel NIR luminescent materials Li2ZnGe3O8:xMn2+

A series of near-infrared (NIR) emitting Li2ZnGe3O8 (LZG):xMn2+ phosphors were synthesized via a conventional solid state reaction. They can be obtained by controlling the heating temperature (950 °C) or changing the doping concentration of Mn2+ (900 °C). In particular, due to the transition of the crystal from ZnO6 to ZnO4, the NIR phosphors perform with different spectral widths when the Zn/Mg ratio in LZG:xMn2+ is adjusted. The excitation spectrum is characterized by a broad band from 240 nm to 640 nm, centered at 475 nm and tailing on the low energy side. The emission spectrum presents a broad emission band from 650 to 900 nm with the main peak at 832 nm. Hence, the phosphors can convert visible and ultraviolet light to NIR emission. What's more, this kind of NIR phosphor is based on the mechanism of down-conversion, and it possesses excellent thermal effect properties.