Symmetry-Related Transitions in the Spectrum of Nanosized Cubic Y₂O₃:Tb³⁺

Abstract

Herein the preparation and cathodoluminescence of nanoparticles of cubic Y 2 O 3 :Tb 3+ having Tb 3+ concentration varying between 0.1 and 10 Mol% are described. The cathodoluminescence spectra were recorded with a high resolution spectrometer, which enabled the identification of Tb 3+ lines with C 2 and S 6 symmetry: the lines at 542.8 nm and 544.4 nm were designated as 5 D 4 → 7 F 5 (C 2 ) and 5 D 4 → 7 F 5 (S 6 ) respectively. The critical distance for energy transfer from Tb 3+ ions at S 6 lattice sites to Tb 3+ ions at C 2 lattice sites was found to be >1.7 nm. At the greater distances which prevail at low Tb 3+ concentration, this energy transfer virtually stops. From cathodoluminescence spectra recorded in a scanning transmission electron microscope it was concluded that this energy transfer also did not take place if the temperature was reduced below 102 K. 2 The idiosyncrasy of the luminescence spectra of Tb 3+ doped phosphors was nicely summarized by Blasse and Grabmaier: domination by the 5 D 4 → 7 F J (J = 2, 3, 4, 5 and 6) transitions, contribution of (weak) 5 D 3 → 7 F J transitions in the blue and a complicated structure of the crystal field splitting because of the rather high J quantum numbers.3 Figure 1 shows the high resolution CL spectrum of cubic nanosized Y 2 O 3 :Tb 3+ with 1% Tb 3+ recorded by us at an electron energy of 15 keV, current density of 2 μA/cm 2 and room temperature. The spectral radiance of the 5 D 3 → 7 F J transitions in the blue region of the spectrum is very small and cannot be observed in Figure 1. The inset shows a detail of the spectrum between 535 nm and 560 nm: 10 peaks can be observed at these conditions. Because of the complicated configuration of the peaks in the various 5 D 4 → 7 F J transition clusters, a detailed designation of the lines to specific crystal-field-splitting levels has not been established. A second complication in identifying the spectral lines of Y 2 O 3 :Tb 3+ is related to the crystal structure of the Y 2 O 3 -host. It has been well established that Y 2 O 3 doped with various concentrations of Tb 3+ and annealed at temperatures above 900• C has the cubic structure of the mineral bixbyite; 4-10 moreover, the cell constant of the unit cell, 1.060 nm, does not change upon doping. 6This cubic structure has two different Y 3+ lattice sites, which possess the point symmetries C 2 and S 6 : 24 lattice sites have C 2 symmetry, while the other 8 have S 6 symmetry.11 These sites are shown in Figure 2 , we need to identify C 2 and S 6 transitions in the spectrum.In spite of the absence of any assignment of the lines in the various 5 D 4 → 7 F J transition clusters, the scientific work on nanosized Y 2 O 3 :Tb 3+ is progressing. [5][6][7][8][9][10][12][13][14][15][16] The majority of these recent studies have dealt with photoluminescence (PL) of Y 2 O 3 :Tb 3+ ; however, Alarcón-Flores et al. 12 and Cho et al. 13 have used cathodoluminescence (CL), while Cress et al.14 have applied alpha particles (radioluminescence) to excite the phosphor. In the PL stu...

Symmetry-Related Transitions in the Photoluminescence and Cathodoluminescence Spectra of Nanosized Cubic Y2O3:Tb3+

“…The resolution of the spectrometer was insufficient to detect the doublet structure of the strong emission lines at 542.5 and 544.2 nm. 1 The absolute wavelength calibration of this emission monochromator could be off by maximally 0.4 nm; however, relative wavelength values were accurate within 0.3 nm. All PL spectra were recorded at room temperature.…”

Paper No S10.4: Transmission Electron Microscope Study of Symmetry‐related Transitions in Cubic Y2O3:Tb3+

“…This cubic structure has two different Y 3+ lattice sites, which possess the point symmetries C 2 and S 6 : 24 lattice sites have C 2 symmetry, while the other 8 have S 6 symmetry . From the concentration dependency of a few spectral lines of Y 2 O 3 :Tb 3+ we could assign these as being S 6 ; the majority of the spectral lines has C 2 symmetry . The strongest S 6 line in the Y 2 O 3 :Tb 3+ spectrum is located in the 4 D 5 → 7 F 5 cluster at 544.4 nm.…”

“…The industrial applications of yttrium oxide doped with europium or terbium have stimulated scientists to investigate the energy flow in these materials upon excitation by electrons or UV‐radiation. For cubic Y 2 O 3 :Eu 3+ a symmetry‐related energy flow scheme was proposed in the 1980s , while we have recently proposed such a scheme for Y 2 O 3 :Tb 3+ . The complicated nature of the spectrum of Y 2 O 3 :Tb 3+ impedes the assignment of the transitions in the 4 D 5 → 7 F J (where J = 2, 3, 4, 5, and 6) clusters.…”

Luminescence of Eu3+ ions in hybrid polymer‐inorganic composites based on poly(methyl methacrylate) and zirconia nanoparticles

“…The decrease in the size of the host matrix (ZrO 2 ) affects such properties as quantum efficiency and luminescence lifetime. Therefore, the study of the crystal field effect on the luminescent properties of the material is important for determining the possible areas of its application …”

“…Therefore, the study of the crystal field effect on the luminescent properties of the material is important for determining the possible areas of its application. [50,51] This work aimed to synthesize functional polymer-inorganic composites based on PMMA and ZrO 2 nanoparticles doped with different amounts of Eu 3+ ions, as well as to study the effect of the polymer matrix, phase composition and surface modification of the inorganic filler on the photoluminescence (PL) properties of the obtained materials. Therefore, nanoparticles of ZrO 2 -EuO 1.5 solid solutions were synthesized, their surface was modified by compounds of a vinyl series with a different structure (3-(trimethoxysilyl) propyl methacrylate, dimethoxymethylvinyl silane, and 2-hydroxyethyl methacrylate), and luminescent composites based on PMMA were prepared by in situ radical polymerization in bulk.…”