Characterization and optical properties of (Gd1-x, Prx)2O2S nano-phosphors synthesized using a novel co-precipitation method

A novel co-precipitation method for synthesizing (Gd1-x, Pr-x)(2)O2S nano-phosphors was developed, using the commercially available Gd2O3, Pr6O11, H2SO4 and NaOH as the starting materials. This method has the advantage of controllable phosphor particle size and shape, simplicity in processing, low cost, and not involving toxic carbon disulfide or hydrogen sulfide. It was found that the as-synthesized precursor is mainly composed of (Gd1-x, Pr-x)(2)(OH)(4)SO4 center dot nH(2)O. By calcining the (Gd1-x, Pr-x)(2)(OH)(4)SO4 center dot nH(2)O precursor at a temperature higher than 700 C for 1 h in flowing hydrogen, pure quasi-spherical shaped (Gd1-x, Pr-x)(2)O2S particles can be synthesized. The (Gd1-x, Pr-x)(2)O2S particles have a narrow size distribution with a mean grain size of about 20-30 nm. UV-vis spectra indicates that the absorption edge of the samples has a blue shift with increasing calcination temperature, while PL spectra of (Gd1-x, Pr-x)(2)O2S under 301 nm excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the P-3(0) -> H-3(4) transition of Pr3+ ions. The optimal x value is 0.01 for the highest luminescent emission intensity. (C) 2010 Elsevier B.V. All rights reserved.