Tunable Luminescence Properties of CaIn₂O₄:Eu³⁺ Phosphors

Abstract

CaIn2O4:Eu3+ phosphors were prepared by a Pechini sol−gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), cathodoluminescence (CL) spectra as well as lifetimes were utilized to characterize the samples. The XRD results reveal that the samples begin to crystallize at 800 °C, and the crystallinity increases upon raising the annealing temperature. The FE-SEM images indicate that the CaIn2O4:Eu3+ samples consist of fine and spherical grains with size around 200−400 nm. Under the excitation of ultraviolet light and low-voltage electron beams, the CaIn2O4:Eu3+ phosphors show the characteristic emissions of Eu3+ (5DJ−7FJ‘ J, J‘ = 0, 1, 2, 3 transitions). The luminescence color can be tuned from white to orange to red by adjusting the doping concentration of Eu3+. The corresponding luminescence mechanisms have been proposed.