Preparation and luminescence property of Gd2O2S:Tb X-ray nano-phosphors using the complex precipitation method

The Gd2O2S:Tb X-ray nano-phosphors were prepared using the complex precipitation method combined with low temperature sulfurized method. The mixed solution of the ammonium water and ammonium hydrogen carbonate was employed as the complex precipitant. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), photoluminescence (PL) and X-ray excited luminescence (XL) spectra. The results show that the as-prepared samples can be sulfurized completely at 900 oC with flowing N2 containing sulfur vapor, and show the pure Gd2O2S phases with the hexagonal structure. The obtained X-ray phosphor particles are quasi-spherical, disperse well. And the observed particle size of the sample calcined at 900 oC is 30-50 nm, while the one calcined at 1100 oC is about 50-70 nm. Therefore, both of them have successfully realized the nano-sized, which are beneficial to enhance the resolution of imaging system efficiently. When excited by the 254 nm UV light and X-ray, the Gd2O2S:Tb X-phosphors exhibit the same characteristic emission of Tb3+, which arise from the transitions of 5D3 and 5D4 excited levels to 7F J (J = 0-6) ground states. And the luminescence property of the nanocrystals and the process of energy transfer are studied in details