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Gramatte S, Jeurgens LPH, Politano O, Simon Greminger JA, Baras F, Xomalis A, Turlo V. Atomistic Simulations of the Crystalline-to-Amorphous Transformation of γ-Al 2O 3 Nanoparticles: Delicate Interplay between Lattice Distortions, Stresses, and Space Charges. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6301-6315. [PMID: 37097742 DOI: 10.1021/acs.langmuir.2c03292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The size-dependent phase stability of γ-Al2O3 was studied by large-scale molecular dynamics simulations over a wide temperature range from 300 to 900 K. For the γ-Al2O3 crystal, a bulk transformation to α-Al2O3 by an FCC-to-HCP transition of the O sublattice is still kinetically hindered at 900 K. However, local distortions of the FCC O-sublattice by the formation of quasi-octahedral Al local coordination spheres become thermally activated, as driven by the partial covalency of the Al-O bond. On the contrary, spherical γ-Al2O3 nanoparticles (NPs) (with sizes of 6 and 10 nm) undergo a crystalline-to-amorphous transformation at 900 K, which starts at the reconstructed surface and propagates into the core through collective displacements of anions and cations, resulting in the formation of 7- and 8-fold local coordination spheres of Al. In parallel, the reconstructed Al-enriched surface is separated from the stoichiometric core by a diffuse Al-depleted transition region. This compositional heterogeneity creates an imbalance of charges inside the NP, which induces a net attractive Coulombic force that is strong enough to reverse the initial stress state in the NP core from compressive to tensile. These findings disclose the delicate interplay between lattice distortions, stresses, and space-charge regions in oxide nanosystems. A fundamental explanation for the reported expansion of metal-oxide NPs with decreasing size is provided, which has significant implications for, e.g., heterogeneous catalysis, NP sintering, and additive manufacturing of NP-reinforced metal matrix composites.
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Affiliation(s)
- Simon Gramatte
- Laboratory for Advanced Materials Processing, Empa - Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
- Laboratory for Joining Technologies and Corrosion, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS-Université Bourgogne Franche-Comté, 9 Avenue A. Savary, Dijon F-91191, France
| | - Lars P H Jeurgens
- Laboratory for Joining Technologies and Corrosion, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland
| | - Olivier Politano
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS-Université Bourgogne Franche-Comté, 9 Avenue A. Savary, Dijon F-91191, France
| | - Jose Antonio Simon Greminger
- Laboratory for Advanced Materials Processing, Empa - Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
| | - Florence Baras
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS-Université Bourgogne Franche-Comté, 9 Avenue A. Savary, Dijon F-91191, France
| | - Angelos Xomalis
- Laboratory for Mechanics of Materials and Nanostructures, Empa - Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
| | - Vladyslav Turlo
- Laboratory for Advanced Materials Processing, Empa - Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
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Vasileiadis T, Noual A, Wang Y, Graczykowski B, Djafari-Rouhani B, Yang S, Fytas G. Optomechanical Hot-Spots in Metallic Nanorod-Polymer Nanocomposites. ACS NANO 2022; 16:20419-20429. [PMID: 36475620 PMCID: PMC9798866 DOI: 10.1021/acsnano.2c06673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Plasmonic coupling between adjacent metallic nanoparticles can be exploited for acousto-plasmonics, single-molecule sensing, and photochemistry. Light absorption or electron probes can be used to study plasmons and their interactions, but their use is challenging for disordered systems and colloids dispersed in insulating matrices. Here, we investigate the effect of plasmonic coupling on optomechanics with Brillouin light spectroscopy (BLS) in a prototypical metal-polymer nanocomposite, gold nanorods (Au NRs) in polyvinyl alcohol. The intensity of the light inelastically scattered on thermal phonons captured by BLS is strongly affected by the wavelength of the probing light. When light is resonant with the transverse plasmons, BLS reveals mostly the normal vibrational modes of single NRs. For lower energy off-resonant light, BLS is dominated by coupled bending modes of NR dimers. The experimental results, supported by optomechanical calculations, document plasmonically enhanced BLS and reveal energy-dependent confinement of coupled plasmons close to the tips of NR dimers, generating BLS hot-spots. Our work establishes BLS as an optomechanical probe of plasmons and promotes nanorod-soft matter nanocomposites for acousto-plasmonic applications.
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Affiliation(s)
| | - Adnane Noual
- LPMR,
Département de Physique, Faculté des Sciences, Université Mohammed Premier, Oujda, 60000, Morocco
| | - Yuchen Wang
- Department
of Materials Science and Engineering, University
of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Bartlomiej Graczykowski
- Faculty
of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland
- Max
Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Bahram Djafari-Rouhani
- Département
de Physique, Institut d’Electronique de Microélectonique
et de Nanotechnologie, UMR CNRS 8520, Université
de Lille, Villeneuve
d’Ascq, 59655, France
| | - Shu Yang
- Department
of Materials Science and Engineering, University
of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
| | - George Fytas
- Max
Planck Institute for Polymer Research, 55128 Mainz, Germany
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3
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Griffiths J, Földes T, de Nijs B, Chikkaraddy R, Wright D, Deacon WM, Berta D, Readman C, Grys DB, Rosta E, Baumberg JJ. Resolving sub-angstrom ambient motion through reconstruction from vibrational spectra. Nat Commun 2021; 12:6759. [PMID: 34799553 PMCID: PMC8604935 DOI: 10.1038/s41467-021-26898-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 10/27/2021] [Indexed: 11/09/2022] Open
Abstract
Metal/organic-molecule interactions underpin many key chemistries but occur on sub-nm scales where nanoscale visualisation techniques tend to average over heterogeneous distributions. Single molecule imaging techniques at the atomic scale have found it challenging to track chemical behaviour under ambient conditions. Surface-enhanced Raman spectroscopy can optically monitor the vibrations of single molecules but understanding is limited by the complexity of spectra and mismatch between theory and experiment. We demonstrate that spectra from an optically generated metallic adatom near a molecule of interest can be inverted into dynamic sub-Å metal-molecule interactions using a comprehensive model, revealing anomalous diffusion of a single atom. Transient metal-organic coordination bonds chemically perturb molecular functional groups > 10 bonds away. With continuous improvements in computational methods for modelling large and complex molecular systems, this technique will become increasingly applicable to accurately tracking more complex chemistries.
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Affiliation(s)
- Jack Griffiths
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Tamás Földes
- Department of Chemistry, King's College London, 7 Trinity Street, London, SE1 1DB, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Bart de Nijs
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
| | - Rohit Chikkaraddy
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Demelza Wright
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - William M Deacon
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Dénes Berta
- Department of Chemistry, King's College London, 7 Trinity Street, London, SE1 1DB, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Charlie Readman
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - David-Benjamin Grys
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Edina Rosta
- Department of Chemistry, King's College London, 7 Trinity Street, London, SE1 1DB, UK.,Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | - Jeremy J Baumberg
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
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Wang J, Yang Y, Wang N, Yu K, Hartland GV, Wang GP. Long Lifetime and Coupling of Acoustic Vibrations of Gold Nanoplates on Unsupported Thin Films. J Phys Chem A 2019; 123:10339-10346. [DOI: 10.1021/acs.jpca.9b08733] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Junzhong Wang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Yang Yang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Neng Wang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Kuai Yu
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Gregory V. Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Guo Ping Wang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
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Wang J, Yu K, Yang Y, Hartland GV, Sader JE, Wang GP. Strong vibrational coupling in room temperature plasmonic resonators. Nat Commun 2019; 10:1527. [PMID: 30948721 PMCID: PMC6449381 DOI: 10.1038/s41467-019-09594-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 03/18/2019] [Indexed: 12/22/2022] Open
Abstract
Strong vibrational coupling has been realized in a variety of mechanical systems. However, there have been no experimental observations of strong coupling of the acoustic modes of plasmonic nanostructures, due to rapid energy dissipation in these systems. Here we realized strong vibrational coupling in ultra-high frequency plasmonic nanoresonators by increasing the vibrational quality factors by an order of magnitude. We achieved the highest frequency quality factor products of f × Q = 1.0 × 1013 Hz for the fundamental mechanical modes, which exceeds the value of 0.6 × 1013 Hz required for ground state cooling. Avoided crossing was observed between vibrational modes of two plasmonic nanoresonators with a coupling rate of g = 7.5 ± 1.2 GHz, an order of magnitude larger than the dissipation rates. The intermodal strong coupling was consistent with theoretical calculations using a coupled oscillator model. Our results enabled a platform for future observation and control of the quantum behavior of phonon modes in metallic nanoparticles. Strong vibrational coupling has not been observed in ultra-high frequency mechanical resonators. By engineering phonon dissipation pathways, the authors increase the vibrational quality factor to allow strong coupling observations in plasmonic nanostructures, which has implications for observation and control of quantum phonon dynamics.
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Affiliation(s)
- Junzhong Wang
- College of Electronic Science and Technology, Shenzhen University, Shenzhen, 518060, China
| | - Kuai Yu
- College of Electronic Science and Technology, Shenzhen University, Shenzhen, 518060, China.
| | - Yang Yang
- College of Electronic Science and Technology, Shenzhen University, Shenzhen, 518060, China
| | - Gregory V Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - John E Sader
- ARC Centre of Excellence in Exciton Science, School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Guo Ping Wang
- College of Electronic Science and Technology, Shenzhen University, Shenzhen, 518060, China.
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