Site-splitting inhibition and near-infrared luminescence properties of Cr3+ activated magnetoplumbite SrAl12O19 modified by La and Mg

Near-infrared phosphor-converted light-emitting diodes (pc-LEDs) are attractive in application like in vivo imaging and nondestructive examination in food industry. Plenty of aluminium oxides with high melting point and rigidity have been researched towards high photoluminescence quantum yield and thermal stability. In this work, a series of Cr3+ activated La, Mg modified SrAl12O19 phosphors, i.e. Sr0.7La0.3Mg0.3Al11.7O19, are prepared via a solid-state reaction route. The site splitting and structural evolution towards relative thermodynamic stability in the modified host are discussed, Cr3+ ions with multisite occupation in the host show intense zero -phonon-line (ZPL) emission and tunable broadband emission. The optimized phosphor exhibits excellent luminescence thermal stability, with 98% residual integrity intensity of that at room temperature at 473 K. The results provide a reference for developing novel NIR-emitting magnetoplumbite phosphor with high efficiency and excellent thermal quenching resistance.