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

Herein the preparation and cathodoluminescence of nanoparticles of cubic Y2O3:Tb3+ having Tb3+ 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 Tb3+ lines with C-2 and S-6 symmetry: the lines at 542.8 nm and 544.4 nm were designated as D-5(4)-> F-7(5) (C-2) and D-5(4)-> F-7(5) (S-6) respectively. The critical distance for energy transfer from Tb3+ ions at S6 lattice sites to Tb3+ ions at C-2 lattice sites was found to be > 1.7 nm. At the greater distances which prevail at low Tb3+ 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. The efficiency of the cathodoluminescence of 1% Y2O3:Tb3+ was 6 lm/w at a beam voltage of 15 kV. The decay time of the D-5(4)-> F-7(5) (C-2) transition was substantially shorter than that of the D-5(4)-> F-7(5) (S-6) transition at low Tb3+ concentrations. The decay behavior of the cathodoluminescence images in a field emission scanning electron microscope has been explained in terms of phosphor saturation. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/),which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.