Controlled synthesis and photoluminescence behaviors of Lu2O3:Eu and Lu2O2S:Eu phosphor particles

Abstract Rounded Lu2O3:Eu phosphor powder with an average particle size of ~90 nm was synthesized via pyrolyzing the precipitation precursor prepared by a facile co-precipitation technique using ammonium hydrogen carbonate (AHC) as the precipitant, followed by direct sulfurization at 950 °C under a reducing atmosphere to yield two-dimensional plate-like Lu2O2S:Eu phosphor with a thickness of several micrometers. The photoluminescence (PL) behaviors of the two resultant phosphor powders were systematically investigated. The oxide and oxysulfide phosphors displayed characteristic red-light emissions of Eu3+ at ~612 and 630 nm, respectively, which were derived from 5D0,1→7FJ (J = 0, 1, 2, 3) transitions of Eu3+. The luminescence quenching types of both phosphors were dominated by exchange interactions and the optimum Eu3+ concentrations were found to be ~2.5 at.% for Lu2O3:Eu and ~1.0 at.% for Lu2O2S:Eu. The oxysulfide phosphor had a PL intensity ~3.5 times stronger than the oxide powder. The Lu2O3:Eu and Lu2O2S:Eu phosphors had CIE color coordinates of (0.65, 0.35) and (0.61, 0.39), which fall into the categories of reddish-orange and orange colors, respectively. A shorter fluorescence lifetime (~602.9 μs) and a higher percentage of excitation absorption (η ≈ 71%) were observed for the oxysulfide relative to those of the oxide (~2.4 ms and η ≈ 35%).