Synthesis and optical properties of (Gd1−x,Eux)2O2SO4 nano-phosphors by a novel co-precipitation method

(Gd1−x,Eux)2O2SO4 nano-phosphors were synthesized by a novel co-precipitation method from commercially available Gd2O3, Eu2O3, H2SO4 and NaOH starting materials. Composition of the precursor is greatly influenced by the molar ratio of NaOH to (Gd1−x,Eux)2(SO4)3 (the m value), and the optimal m value was found to be 4. Fourier transform infrared spectrum (FT-IR) and thermal analysis show that the precursor (m = 4) can be transformed into pure (Gd1−x,Eux)2O2SO4 nano-phosphor by calcining at 900 °C for 2 h in air. Transmission electron microscope (TEM) observation shows that the Gd2O2SO4 phosphor particles (m = 4) are quasi-spherical in shape and well dispersed, with a mean particle size of about 30–50 nm. Photoluminescence (PL) spectroscopy reveals that the strongest emission peak is located at 617 nm under 271 nm light excitation, which corresponds to the 5D0 → 7F2 transition of Eu3+ ions. The quenching concentration of Eu3+ ions is 10 mol% and the concentration quenching mechanism is exchange interaction among the Eu3+ ions. Decay study reveals that the 5D0 → 7F2 transition of Eu3+ ions has a single exponential decay behavior.