Monodispersed Colloidal Spheres for Uniform Y₂O₃:Eu³⁺ Red-Phosphor Particles and Greatly Enhanced Luminescence by Simultaneous Gd³⁺ Doping

Abstract

Uniform red-phosphor spheres (∼60-300 nm in diameter) of Y 2 O 3 :Eu 3+ binary and (Y,Gd) 2 O 3 :Eu 3+ ternary systems exhibiting excellent emission at 610 nm have been converted from their colloidal precursor spheres synthesized via homogeneous precipitation. The precursor spheres (approximate composition: [(Y 1-x Gd x ) 1-y -Eu y ](OH)CO 3 • 1.3H 2 O, x ) 0-0.5 and y ) 0-0.11) are directly solid solutions, but arising from sequential nucleation each of the spheres has more Gd and especially Eu while having less Y going from the particle surface to the core. Eu 3+ is more effective than Gd 3+ in raising nucleation density, leading to rapidly decreased average size of the precursor particles at a higher Eu 3+ addition. Diminishing the concentration gradients through adequate annealing is identified to be crucial to high luminous intensity of the oxide particles. At the optimal annealing temperature of 1000 °C, cation homogenization is achieved and the oxide particles largely retain their precursor morphologies, yielding dispersed uniform spheres of excellent luminescence. The (Y 1-x -Eu x )O 1.5 phosphor particles exhibit typical red emissions at 610 nm upon UV excitation into the charge transfer band at ∼255 nm, and the quenching concentration of Eu 3+ is found to be ∼5 at. %. Partially replacing Y 3+ with Gd 3+ (up to 50 at. %) while keeping Eu 3+ at the optimal content of 5 at. % linearly improves the 610 nm emission, and the phosphor particles of [(Y 0.5 Gd 0.5 ) 0.95 Eu 0.05 ]O 1.5 exhibit an luminous intensity ∼103% of that of a commercially available Y 2 O 3 :Eu red phosphor. The uniform phosphor spheres obtained in this work are expected to have wide applications in high-resolution display technologies of contemporary interest.

Monodisperse colloidal spheres for (Y,Eu)2O3red-emitting phosphors: establishment of processing window and size-dependent luminescence behavior

“…It relies 3 ) into the reaction system [5][6][7][8][9][10][11][12]. Systems containing one rare-earth element (RE) were systematically studied by Matijević and Hsu [5], Hsu et al [6], Aiken et al [7], Sordelet and Akinc [8] and Sordelet and Akinc [9] through UBHP processing.…”

“…Systems containing one rare-earth element (RE) were systematically studied by Matijević and Hsu [5], Hsu et al [6], Aiken et al [7], Sordelet and Akinc [8] and Sordelet and Akinc [9] through UBHP processing. More recently, Li et al [10][11][12] have extended their compositions to Y/Gd, Y/Eu, Gd/Eu and even Y/Gd/Eu mixed systems. They also proposed using the monodisperse basic carbonate colloid spheres processed via UBHP as the precursors for luminescent oxides, which definitely widens the practical applications of these phosphors.…”

“…They also proposed using the monodisperse basic carbonate colloid spheres processed via UBHP as the precursors for luminescent oxides, which definitely widens the practical applications of these phosphors. This approach resulted not only in monodispersity of the phosphor spheres but also in markedly enhanced luminescence [11]. While the previous studies largely focused on the effect of RE doping and solvent on the particle morphology and formation mechanism under a fixed processing condition, the range of processing parameters was not well defined, although it is important for applications.…”

Cathodoluminescence Properties of In2O3-coated Y2O3:Eu3+

“…[4][5][6] The quantum yield of this emission varies from 60 to 74% depending on the porosity of the Y2O3:Eu 3+ particle. …”

“…[4][5][6] The quantum yield of this emission varies from 60 to 74% depending on the porosity of the Y2O3:Eu 3+ particle. 7 Recently, this phosphor has attracted a great deal of attention for use in field emission displays (FEDs), since it is presumed to be inherently stable under electron beam excitation.…”