Ca₃Lu(AlO)₃(BO₃)₄ : Sm³⁺: a novel red-emitting phosphor with high colour purity for NUV-based warm white LEDs

In the present work, we described the synthesis of a novel phosphor Ca₃Lu(AlO)₃(BO₃)₄ (CLAB) activated with Sm³⁺ via high temperature solid-state reaction. X-ray diffraction (XRD), FTIR spectra, diffuse reflection spectra, photoluminescence (PL) spectra and fluorescence decay curves were used to characterize the as-synthesized samples. The morphology and chemical composition were measured by field emission scanning electron microscope (FE-SEM) and X-ray energy diffraction spectroscopy (EDAX). The structure refinements from XRD data revealed the isostructural arrangement of CLAB : Sm³⁺ to gaudefroyite with a hexagonal P6₃/m space group in which the AlO₆ octahedral chains are interconnected by BO₃ triangles in the ab plane to form a Kagome-type lattice (star-shaped), leaving trigonal and apatite-like-tunnels. Under 404 nm excitation, the as-synthesized phosphor shows an intensely red emission peaked at 614 nm with CIE coordinates of (0.615, 0.380) and high colour purity up to 98.53%. The quantum yield of the phosphor was found to be 15.5% with a desired doping concentration of 5 mol% Sm³⁺ ions. The red emission intensity of CLAB : 0.05Sm³⁺ at 425 K is 86.6% of that at 300 K. All these good properties make the phosphor of CLAB : Sm³⁺ exhibit a great potential for application in UV-based warm white LEDs used in displays.