Enhanced Blue Emission in CaAl₂Si₂O₈:Eu²⁺ Phosphor Near-UV Excitation for Potential Solid-state Lighting Applications

The novel CaAl₂Si₂O₈:Eu²⁺ (x = 0.5, 0.7, 1.0, 1.3 and 1.5 mol%) phosphor was successfully prepared by a simple combustion process. The phase and purity were investigated by X-ray diffraction (XRD), which shows a pure crystalline phase and matches the standard ICSD database file. The Rietveld refinement performed using an acceptable chi-square to determine additional structural parameters. The FTIR analysis is done to determine the functional group present in the given sample. UV-Vis diffuse reflectance spectroscopy used to determine the optical band gap reveals that the host is suitable for luminescence applications. The optical properties studied using Photoluminescence (PL) spectroscopy show a diffuse band in the blue-green region under near-UV excitation, due to the allowed 4f⁶5d¹ → 4f⁷ transitions of Eu²⁺ ions. The emission intensity varied with dopant concentration, with the highest at 1.0 mol%, followed by concentration quenching at higher concentrations. The surface morphology, determined using field-emission scanning electron microscopy (FE-SEM), revealed an agglomerated structure, and energy-dispersive spectroscopy (EDS) analysis confirmed the presence of all constituents in the host matrix. These findings reveal that the novel CaAl₂Si₂O₈:Eu²⁺ phosphor is a promising luminescence material for white LED devices and solid-state lighting applications.