Luminescence Properties of Y₂O₃:Tb³⁺Whiskers Fabricated by Chemical Vapor Deposition

Abstract

Luminescence properties of highly h100i-oriented Y 2 O 3 :Tb 3þ whiskers obtained by chemical vapor deposition on Si substrate have been investigated over a wide temperature range for different dopant concentrations. A considerable thermally stimulated increase of the green Tb 3þ emission intensity was found in the temperature range of 98-433 K under 325 nm laser excitation. At temperatures higher than 433 K, the emission exhibits temperature quenching with the activation energy of $0:98 eV. This behavior is discussed on the basis of the results of the time-decay measurements of the emission in the temperature range of 300-773 K. The thermally stimulated intensity increase is attributed to the thermal broadening of the photoluminescence excitation spectrum, whereas the temperature quenching is tentatively ascribed to the thermal activation of electrons from the excited 4f 7 5d configuration to the conduction band. The decay time of the green Tb 3þ emission exhibits shortening with increasing dopant concentration, which is considered in terms of the energy transfer processes between the Tb 3þ ions.

Effects of Tb doping on the photoluminescence of Y2O3:Tb nanophosphors

“…The maxima are centered at 277 and 304 nm, in agreement with previous reports [15,16]. The origin of these bands has been associated with either charge-transfer absorption or Tb 3+ intra-band (4f 8 -4f 7 5d) excitation [15,17]. The emission spectra are complex, containing several groups of sharp lines associated with electronic transitions of the Tb 3+ ion.…”

“…Two of the corners are unoccupied with the vacancies being either along the cube diagonal or along a face diagonal [14]. Optical emission and excitation of RE-doped Y 2 O 3 have been investigated in both bulk and nanostructured materials [5][6][7][8][15][16][17], and we summarize the main results obtained from previous studies on Tb-doped Y 2 O 3 (Y 2 O 3 :Tb) nanophosphors.…”

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

“…The E1-peak is broader than the E2 peak. Najafov et al 4 and Som et al 12 also made a Gaussian deconvolution of the excitation band for Y 2 O 3 :Tb 3+ between 250 nm and 340 nm. They also found that the E2 peak was narrower than the E1-peak.…”

“…Najafov et al did not refer to these phenomena in their paper. 4 Concentration quenching was identified as an important issue in several publications on the PL spectrum of Y 2 O 3 :Tb 3+ . It was discussed by Najafov et al 4 and measured by Muenchausen et al; 5 these latter authors found that the PL efficiency peaked at 0.5 Mol% in bulk Y 2 O 3 :Tb 3+ material, whereas for their nano-material with particle size of 35 nm it peaked at 1.5% Tb 3+ .…”

“…4 Concentration quenching was identified as an important issue in several publications on the PL spectrum of Y 2 O 3 :Tb 3+ . It was discussed by Najafov et al 4 and measured by Muenchausen et al; 5 these latter authors found that the PL efficiency peaked at 0.5 Mol% in bulk Y 2 O 3 :Tb 3+ material, whereas for their nano-material with particle size of 35 nm it peaked at 1.5% Tb 3+ . Wang et al 6 found that the 5 were given by Ropp, 8 Najafov et al, 4 Muenchausen et al, 5 Meng et al, 9 Liu et al, 10 Ray et al, 11 Loitongbam et al 12 and Som et al 13 Most authors assigned the broad excitation band between 260 nm and 310 nm to a 4f 8 →4f 7 5d 1 transition in the Tb 3+ ion.…”