Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln(3+)-Doped Gd2O3 Nanotubes
authors Macedo, AG; Ferreira, RAS; Ananias, D; Reis, MS; Amaral, VS; Carlos, LD; Rocha, J
nationality International
journal ADVANCED FUNCTIONAL MATERIALS
keywords OXIDE NANOTUBES; LUMINESCENT MATERIALS; MAGNETIC-PROPERTIES; OPTICAL-PROPERTIES; LANTHANIDE IONS; NANOCRYSTALS; NANORODS; NANOPARTICLES; STATE; NANOPHOSPHORS
abstract There is a growing interest in understanding how size-dependent quantum confinement affects the photoluminescence efficiency, excited-state dynamics, energy-transfer and thermalization phenomena in nanophosphors. For lanthanide (Ln(3+))-doped nanocrystals, despite the localized 4f states, confinement effects are induced mostly via electron-phonon interactions. In particular, the anomalous thermalization reported so far for a handful of Ln(3+)-doped nanocrystals has been rationalized by the absence of low-frequency phonon modes. This nanoconfinement may further impact on the Ln(3+) luminescence dynamics, such as phonon-assisted energy transfer or upconversion processes. Here, intriguing and unprecedented anomalous thermalization in Gd2O3:Eu3+ and Gd2O3:Yb3+,Er3+ nanotubes, exhibiting up to one order of magnitude larger than previously reported for similar materials, is reported. This anomalous thermalization induces unexpected energy transfer from Eu3+ C-2 to S-6 crystallographic sites, at 11 K, and H-2(11/2) -> I-4(15/2) Er3+ upconversion emission; it is interpreted on the basis of the discretization of the phonon density of states, easily tuned by varying the annealing temperature (923-1123 K) in the synthesis procedure, and/or the Ln(3+) concentration (0.16-6.60%).
publisher WILEY-BLACKWELL
issn 1616-301X
year published 2010
volume 20
issue 4
beginning page 624
ending page 634
digital object identifier (doi) 10.1002/adfm.200901772
web of science category Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter
subject category Chemistry; Science & Technology - Other Topics; Materials Science; Physics
unique article identifier WOS:000275137900012
  ciceco authors
  impact metrics
times cited (wos core): 40
journal impact factor (jcr 2016): 12.124
5 year journal impact factor (jcr 2016): 12.362
category normalized journal impact factor percentile (jcr 2016): 92.921
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