Structurally stable Mn4+-doped oxide phosphor with improved thermal stability for agricultural lighting

Structural and thermal stability are two essential conditions in phosphor research, which are related to the structure of the host and the position of 4 T 2 energy lever in Mn 4+ -activated phosphors. Here, Mn 4+ -activated CaGdAlO 4 phosphor with superior structural stability was synthesized through systematically screening the aluminate family of ABAlO 4 (A = Mg, Ca, Sr, Ba; B Sc, Lu, Y, Gd, La). Sr 2+ was subsequently introduced to modulate the 4 T 2 state level of Mn 4+ for achieving better thermal stability in CaGdAlO 4 :Sr 2+ ,Mn 4+ phosphor. The luminescence quenching temperature T 1/2 show a parabolic trend with the increasing of Sr 2+ dopant in Ca 1-y GdAlO 4 :ySr 2+ , Mn 4+ phosphors, and change from 403 K to 426 K and 387 K in CaGdAlO 4 :Mn 4+ , Ca 0.4 GdAlO 4 :0.6Sr 2+ ,Mn 4+ and SrGdAlO 4 :Mn 4+ three samples, respectively. The corresponding crystal-field calculations confirm that a certain amount of Sr 2+ doping can improve the 4 T 2 state of Mn 4+ and obtain better thermal stability in the phosphor. All the samples have deep-red emission located at 712 nm, which matches well with the absorption spectra of green vegetables. This deep-red light accelerate morphological formation and increase vegetable biomass. This work is expected to stimulate more exploration of Mn 4+ -doped oxide phosphors with better structural and thermal stability for emerging applications of agricultural lighting.