LAUSR

Abstract Uniform spheres of (Gd 1− x Dy x ) 2 O 3 ( x =0.01–0.10) have been converted from their colloidal precursor spheres synthesized via homogeneous precipitation. The synthesis, particle size control, luminescent properties and energy transfer of the (Gd 1 -x Dy x ) 2 O 3 were systematically studied by the combined techniques of fourier transform infrared (FT-IR) spectroscopy, x-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence excitation/ photoluminescence (PLE/PL) spectroscopy, and fluorescence decay analysis. The precursor exhibit mono-dispersed spherical morphology and its size can be efficiently controlled by adjusting the urea content. The phase pure (Gd 1− x Dy x ) 2 O 3 oxides can be obtained by calcining precursor at 600 °C, and the spherical morphology remained at even high temperature of 1000 °C. The (Gd 1− x Dy x ) 2 O 3 phosphors display strong yellow emission at 575 nm ( 4 F 9/2 → 6 H 13/2 transition of Dy 3+ ) and weak blue emission at 486 nm ( 4 F 9/2 → 6 H 15/2 transition of Dy 3+ ) upon ultraviolet (UV) excitation of Gd 3+ at 275 nm ( 8 S 7/2 → 6 I J transition of Gd 3+ ). The optimal content of Dy 3+ was found to be ~2 at% ( x =0.02) due to the concentration quenching. Owing to the efficient Gd 3+ →Dy 3+ energy transfer, the fluorescent property of the phosphor was significantly improved. The emission intensity of (Gd 1− x Dy x ) 2 O 3 increased with calcination temperature and particle size increasing, while the lifetime for the 575 nm emission gradually decreased. The (Gd 1− x Dy x ) 2 O 3 spheres developed in the present work is expected to be a promising yellow phosphor widely used in the lighting and display areas.