Phonon density of states in lanthanide-based nanocrystals
| العنوان: | Phonon density of states in lanthanide-based nanocrystals |
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| المؤلفون: | Frank Weber, Karl Krämer, Rolf Heid, Radian Popescu, Ian A. Howard, Dagmar Gerthsen, Bryce S. Richards, Damien Hudry, Michael Merz, Ayman Said, Dmitry Busko, Z. H. Li, Manh Duc Le |
| المصدر: | Physical Review B. 102 |
| بيانات النشر: | American Physical Society (APS), 2020. |
| سنة النشر: | 2020 |
| مصطلحات موضوعية: | Lanthanide, Materials science, Condensed Matter - Mesoscale and Nanoscale Physics, 530 Physics, Phonon, Phonon density of states, FOS: Physical sciences, Physics::Optics, Quantum yield, Surface phonon, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Photon upconversion, Condensed Matter::Materials Science, Crystallography, Nanocrystal, Condensed Matter::Superconductivity, 540 Chemistry, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Vibrational spectra |
| الوصف: | 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 ${\mathrm{NaY}}_{0.8}{\mathrm{Yb}}_{0.18}{\mathrm{Er}}_{0.02}{\mathrm{F}}_{4}$ and $\mathrm{Na}{\mathrm{Gd}}_{0.8}{\mathrm{Yb}}_{0.18}{\mathrm{Er}}_{0.02}{\mathrm{F}}_{4}$. 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, $E\ensuremath{\le}15\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$, in ultrasmall (5 nm) $\mathrm{Na}{\mathrm{Gd}}_{0.8}{\mathrm{Yb}}_{0.18}{\mathrm{Er}}_{0.02}{\mathrm{F}}_{4}$ 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. |
| تدمد: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.102.165409 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2cbd7b48010315033c532c8f84d31dc8 https://doi.org/10.1103/physrevb.102.165409 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....2cbd7b48010315033c532c8f84d31dc8 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 24699969 24699950 |
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| DOI: | 10.1103/physrevb.102.165409 |