Tuning luminescence properties of Eu3+ doped CaAl2O4 nanophosphores with Na+ co-doping

Nanosized CaAl2O4 powders doped with Eu3+ and charge compensated with Na+ co-doping were synthesized with modified Pechiniʹs method. The structural properties of the powders calcined at 900–1100 °C where characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The grains with monoclinic structure formed quite large and aggregated crystallites with irregular shapes and sizes in the range of 100–500 nm. The photoluminescent properties of the phosphores co-doped with different Eu3+ ions concentration (0.5–5 mol%) were investigated by excitation and emission spectroscopy at room and low (77 K) temperatures. The effect of charge compensation on luminescence properties was noticed. To explain these differences a detailed analysis of luminescence spectra by the Judd–Ofelt theory has been performed.