Controlled Synthesis And Optical Properties Of Heavy Rare Earth Luminescent Materials Of Lu₂O₃:RE And Lu₂O₂S:RE

Due to its novel optical and chemical properties,the lanthanide elements have made lanthanide-doped oxides and sulfur oxides one of the most popular luminescent powders,and have been widely used in high-performance light-emitting devices,magnets,catalysts and other functional materials.Based on this,the experiments in this paper have prepared pure phase luminescent powders doped with Eu and Dy using Lu₂O₃and Lu₂O₂S as the matrix by simple co-precipitation and solid-phase reaction.And the growth process and luminescence performance were systematic research.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 at950°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?612nm and 630 nm,respectively,which were derived from ⁵D_0,1?⁷F_J(J=0,1,2,3)transitions of Eu^3+.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?s)and a higher percentage of excitation absorption(??71%)were observed for the oxysulfide relative to those of the oxide(?2.4 ms and??35%).Using the same co-precipitation and solid-phase reaction method,Dy³⁺-doped oxide and sulfur oxide luminescent powders were prepared.The obtained Lu₂O₃:Dy and Lu₂O₂S:Dy luminescent powders are consistent with Eu³⁺-doped phosphors in terms of morphology,and are respectively spherical and two-dimensional plate-like powders with a thickness of several nanometers.However,the photoluminescence(PL)behavior of the two luminescent powders has changed,and the emission spectra of oxide and sulfur oxide luminescent powders doped with Dy³⁺are no longer just characteristic peaks of a single color.Lu₂O₃:Dy observed two main emission peaks at 493nm and 546 nm,respectively from the ⁴F_9/2?⁶H_15/2transition in the blue region and the ⁴F_9/2?⁶H_13/2transition in the yellow region,whose CIE color coordinates are(0.34,0.46).The obvious peaks of Lu₂O₂S:Dy in the blue region are at 488 nm and 515 nm from ⁴F_9/2?⁶H_15/2transitions,and the obvious peaks in the yellow region are at 541 nm,580 nm and 628 nm,from⁴F_9/2?⁶H_13/2For the transition,the CIE color coordinates are(0.34,0.46)and(0.35,0.48).Both of them all show yellow-green.The optimal doping concentrations of Dy in oxide and sulfur oxide luminescent powders are?0.05 at.%and?1.0 at.%,respectively.Consistent with Eu doping is that compared to Dy³⁺doped oxides(?6.109 ms and??3.21%),the sulfur oxide has a shorter fluorescence lifetime(?1.17 ms)and a higher excitation absorption percentage(??21.4%).