Cathodoluminescence of Y₂O₃:Ln³⁺ (Ln = Tb, Er and Tm) and Y₂O₃:Bi³⁺ nanocrystalline particles at 200 keV

Abstract

The cathodoluminescence (CL) spectra of nanocrystalline Y 2 O 3 :Tb 3+ (0.3%), Y 2 O 3 :Er 3+ (1%), Y 2 O 3 :Tm 3+ (2%) and Y 2 O 3 :Bi 3+ (1%) were recorded in a transmission electron microscope at 200 keV, low current density and various temperatures. The quenching energy of the intrinsic luminescence of the various Y 2 O 3 :Ln 3+ (Ln ¼ Tb, Er and Tm) phosphors was found to be 0.25 eV. The intrinsic luminescence and the strongest spectral transitions of Ln 3+ in these three phosphors exhibit similar temperature behaviour at temperatures > À50 C, viz. a small increase of the spectral radiance upon increasing the temperature.Increasing the temperature beyond À50 C led to complete quenching of the intrinsic luminescence at room temperature, whereas the radiance of the Ln 3+ spectral transitions only decreased slightly. An extended Jablonski diagram for the energy transfer from the self-trapped exciton states in Y 2 O 3 to the Ln 3+ and Bi 3+ ions is proposed. This diagram also indicates why Tb 3+ is a better quencher of the intrinsic luminescence in Y 2 O 3 than Er 3+ and Tm 3+ . The intrinsic luminescence of Y 2 O 3 :Bi 3+ largely overlapped with the blue Bi 3+ emission band, which made an accurate analysis of its temperature behaviour impossible. Nevertheless, we concluded that upon increasing the temperature energy from Bi 3+ ions at the C 3i sites is transferred to Bi 3+ ions at C 2 sites. From the temperature behaviour of the 539 nm transition of the 2 H 11/2 / 4 I 15/2 manifold of Y 2 O 3 :Er 3+ the activation energy for this transition could be determined: viz. 0.078 eV (623 cm À1 ). rsc.li/rsc-advances 396 | RSC Adv., 2018, 8, 396-405 This journal isFig. 15 Arrhenius plot of the radiances of the 539.2 nm and 538.3 nm peaks of Y 2 O 3 :Er 3+ . 404 | RSC Adv., 2018, 8, 396-405 This journal is

Photoluminescence and cathodoluminescence of BaAl2O4:Eu2+ and undoped BaAl2O4: evidence for F-centres

“…The explanation above on the origin of the 430 nm band in BaAl 2 O 4 :Eu 2+ is an important building block for its mixed luminescence: intrinsic lattice luminescence (F-centre) and Eu 2+ luminescence. This type of mixed luminescence has been described by us in an earlier study on Y 2 O 3 :Ln 3+ (Ln = Eu, Tb, Tm and Er) [53,54].…”

Comparative Analysis of the Electronic Energy Structure of Nanocrystalline Polymorphs of Y2O3 Thin Layers: Theory and Experiments

“…13). These emission bands are associated with radiative de-excitation of the self-trapped exciton [24,42,43]. Note also that for bulk Y2O3 the exciton emission band is shifted to the high-energy region (3.4-3.5 eV) [41].…”