Luminescence properties of Mn4+-doped CaAl2O

Abstract

Akin to the enormous number of discoveries made through luminescence materials, rare earth-doped aluminates are attractive materials for a new class of next generation displays and lighting devices that show merits like high chemical stability, brightness, and flexible industrial processing ability. A series of Mn⁴⁺-activated CaAl₂O₄ (CAO) compounds were synthesized by co-precipitation to seek a candidate for a red-emitting phosphor to be employed in a white LED. The crystal structure, morphology, and fluorescence properties of the as-obtained phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL). The deep red luminescence of Mn⁴⁺ in CaAl₂O₄ is reported and discussed. The excitation spectrum exhibited broadband emission between 260 and 550 nm with three peaks dominating at 320 nm due to the transition of ⁴A₂->⁴T₁. The emission spectra between 600 to 720 nm displays an overwhelming emission peak at 654 nm owing to the ²E->⁴A₂ transition of Mn⁴⁺ ion. This research demonstrates the great promise of CaAl₂O₄:Mn⁴⁺ as a commercial red phosphor in warm white LEDs and opens up new avenues for the exploration of novel non-rare-earth red-emitting phosphors.