Deep-red-emitting Ca2LuSbO6:Mn4+ phosphors for plant growth LEDs: Synthesis, crystal structure, and photoluminescence properties

High-efficiency light source based on inorganic luminescence material is of great benefit to the development of plant cultivation. Herein, a series of novel Mn4+ activated Ca2LuSbO6 compounds with various doping concentrations were synthesized via a high-temperature solid-state reaction. The phase formation and crystal structure were analyzed by X-ray diffraction and the luminescence characteristics were also discussed systematically. The as-prepared samples exhibited two broad excitation bands ascribed to d-d transitions of Mn4+ ions, and upon 345 nm excitation the phosphors showed an intense deep-red emission centered at 683 nm due to the 2Eg→4A2g transition, which matched well with the absorption region of light source required for plant growth (~660 nm). And the Ca2LuSbO6:Mn4+ phosphors exhibited the highest emission intensity when the Mn4+ doping concentration was 0.5 mol%. Additionally, Ca2LuSbO6:0.5%Mn4+ phosphor sample possessed high internal quantum efficiency of 39.1% and its CIE coordinates were (0.725, 0.275). The thermal stability was also commendable that the 683 nm deep-red emission intensity at 423 K (150 °C) maintained 48% of that at room temperature (303 K).