Low-temperature green synthesis of nanocrystalline La2O2S:Pr3+ powders and investigation of photoluminescence

Calcining an amorphous precursor in flowing hydrogen at 900 degrees C directly produced nanocrystalline La2O2S:Pr3+ powder (LOS:Pr3+; average size similar to 35 nm) of a unimodal distribution of particle size (mean diameter similar to 90 nm). The precursor, precipitated by titrating an aqueous solution of rare-earth nitrate and ammonium sulfate with ammonia water, was deduced to have an approximate composition of (La,Pr)(2)(OH)(2.6)(CO3)(0.7)SO4 center dot 2H(2)O. Aside from simplicity, the synthesis method reported herein has the obvious advantage of environmental friendliness, as it did not involve any harmful sulfidizing agent. The products were characterized in detail by XRD, FTIR, TG/DTA, and SEM/TEM to reveal the process of phase/morphology development and fine microstructure. Photoluminescence study found that the LOS:Pr3+ nanopowder exhibited strong luminescence at similar to 508 nm (P-3(0,1) -> H-3(4) transition), with a fluorescence lifetime of similar to 4.22 +/- 0.03 mu s, either through exciting the LOS host (similar to 263 nm, more efficient) or directly exciting the Pr3+ activator (similar to 304 nm), and retained similar to 45% of its room-temperature intensity at 150 degrees C. Aside from phosphor application, the thus-synthesized powder would be useful for the fabrication of ceramic scintillators because of its nanosized crystallites and narrow distribution of particle size. (C) 2022 The Author(s). Published by Elsevier B.V.