Synthesis and characterization of green ribbon-like Gd2O2SO4:Tb3+ phosphors via hydrothermal method followed by calcination

Gd(NO3)(3)center dot 6H(2)O, Tb(NO3)(3)center dot 6H(2)O, L-cysteine (HSCH2CHNH2COOH) and urea (CO(NH2)(2)) were used as experimental starting materials. Among them L-cysteine and urea were used as sulfur source and precipitator, respectively. The precursor was synthesized by hydrothermal reaction at 150 degrees C for 24 h, which was then converted into Gd2O2SO4:Tb3+ green phosphors through calcining at 800 degrees C for 2 h in air. Detailed characterizations were attained by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry/differential scanning calorimetry (TG/DSC), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectra. It was demonstrated that pure Gd2O2SO4 phase could be obtained when Gd(NO3)(3), L-cysteine and urea were mixed in accordance with the molar ratio of 1:2:0.25. The as-obtained Gd2O2SO4:Tb3+ is ribbon-like material with uniform size and improved dispersivity. The thickness of the ribbon-like material is about 8 mu m. The formation mechanism of Gd2O2SO4:Tb3+ phase has also been proposed. Photoluminescence analysis showed that the Gd2O2SO4:6%Tb3+ phosphors had the strongest green emission at 544 nm under 230 nm ultraviolet (UV) light excitation, which corresponded to the D-5(4) -> F-7(5) transition of Tb3+ ions. Those results suggested that the green ribbon-like Gd2O2SO4:Tb3+ phosphors might have potential applications in X-ray intensifying screens, fluorescence and scintiation material fields. (C) 2019 Elsevier Ltd. All rights reserved.