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Phonon density of states in lanthanide-based nanocrystals

Li, Z.H.; Hudry, D.; Heid, R.; Said, A.H.; Le, M.D.; Popescu, R.; Gerthsen, D.; Merz, M.; Krämer, K.W.; Busko, D.; Howard, I.A.; Richards, B.S.; Weber, F.

Abstract (englisch):
We report a combined inelastic neutron- and x-ray-scattering study of the phonon density of states of the nano- and microcrystalline lanthanide-based materials $NaY_{0.8}Yb_{0.18}Er_{0.02}F_{4}$ and $NaGd_{0.8}Yb_{0.18}Er_{0.02}F_{4}$. While
large (20 nm) nanocrystals display the same vibrational spectra as their microcrystalline counterparts, we find an enhanced phonon density of states at low energies, $E\leq 15 meV$, in ultrasmall (5 nm) $NaGd_{0.8}Yb_{0.18}Er_{0.02}F_{4}$
nanocrystals which we assign to an increased relative spectral weight of surface phonon modes. Based on our observations for ultrasmall nanocrystals, we rationalize that an increase of the phonon density of states in large
nanocrystals due to surface phonons is too small to be observed in the current measurements. The experimental approach described in this paper constitutes a step toward the rationalization of size effects on the modification of the absolute upconversion quantum yield of upconverting nanocrystals.


Originalveröffentlichung
DOI: 10.1103/PhysRevB.102.165409
Dimensions
Zitationen: 2
Zugehörige Institution(en) am KIT Institut für Quantenmaterialien und -technologien (IQMT)
Institut für Mikrostrukturtechnik (IMT)
Laboratorium für Elektronenmikroskopie (LEM)
Lichttechnisches Institut (LTI)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 15.10.2020
Sprache Englisch
Identifikator ISSN: 2469-9950, 2469-9969
KITopen-ID: 1000124852
HGF-Programm 43.21.01 (POF III, LK 01) Quantum Correlations in Condensed Matter
Erschienen in Physical review / B
Verlag American Physical Society (APS)
Band 102
Heft 16
Seiten Art.-Nr.: 165409
Schlagwörter KNMF 2018-021-024449 WERA
Nachgewiesen in Dimensions
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