Highly enhanced luminescence of Gd2O3:Ho3+ phosphor by heat treatment

A series of Ho3+ doped gadolinium oxide phosphors were synthesized by co-precipitation method. The structural, morphological and luminescence properties of as-synthesized samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and photoluminescence spectroscopy (PL). The phenomenon found in the phosphors prepared by quenching is that the red-green ratio decreases, and the luminescence changes from yellow to green. In the emission spectra under 363 nm excitation, the strongest emission band was generated at 550 nm, corresponding to the Ho3+ transition of 5S2→5I8. The emission (5F3→5I8, 5F4→5I8, 5S2→5I8, 5F5→5I8, 5I4→5I8) intensity and the chromatic purity were dramatically enhanced by annealing. The influence of Ho3+ concentrations and heating duration on the luminescence properties were also experimentally investigated in this work.