Tunable wide rectangular red fluorescence spectrum based on gradient temperature method

The Mn4+ -doped Li3LaMgTiO6 phosphor is synthesized via the solid-state reaction technique. Through the utilization of a gradient temperature synthesis method, we have observed a "blue shift" phenomenon in the fluorescence peak, whereby the most intense fluorescence peak shifts from 711 nm to 680 nm as temperature increases. When the sintering temperature reaches 1150 0C and the gradient temperature between the top and bottom of the sample reaches 50 0C, a rectangular fluorescence spectrum with full widths at half maximum (FWHM) up to 100 nm and peak width up to 31 nm can be achieved. Drawing on energy level theory, crystal physics, and luminescence theory, this work delves into the fluorescence mechanism underlying the ‘blue shift’ phenomenon. This study demonstrates the significant practical implications of both the gradient temperature method and phosphors in the field of fluorescent materials.