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Pogna EAA, Chumakov AI, Ferrante C, Ramos MA, Scopigno T. Tracking the Connection between Disorder and Energy Landscape in Glasses Using Geologically Hyperaged Amber. J Phys Chem Lett 2019; 10:427-432. [PMID: 30615469 DOI: 10.1021/acs.jpclett.9b00003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Fossil amber offers the unique opportunity to investigate an amorphous material that has been exploring its energy landscape for more than 110 million years of natural aging. By applying different X-ray scattering methods to amber before and after annealing the sample to erase its thermal history, we identify a link between the potential energy landscape and the structural and vibrational properties of glasses. We find that hyperaging induces a depletion of the vibrational density of states in the terahertz region, also ruling the sound dispersion and attenuation properties of the corresponding acoustic waves. Critically, this is accompanied by a densification with structural implications different in nature from that caused by hydrostatic compression. Our results, rationalized within the framework of fluctuating elasticity theory, reveal how upon approaching the bottom of the potential energy landscape (9% decrease in the fictive temperature) the elastic matrix becomes increasingly less disordered (6%) and longer-range correlated (22%).
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Affiliation(s)
- E A A Pogna
- Laboratorio NEST , CNR-INFM and Scuola Normale Superiore , Piazza San Silvestro 12 , I-56127 Pisa , Italy
- Dipartimento di Fisica , Politecnico di Milano , Piazza Leonardo da Vinci 32 , I-20133 Milano , Italy
| | - A I Chumakov
- ESRF-The European Synchrotron Radiation Facility CS40220 , F-38043 Grenoble Cedex, 9, France
- National Research Centre "Kurchatov Institute" , 123182 Moscow , Russia
| | - C Ferrante
- Dipartimento di Fisica , Universitá di Roma , La Sapienza , I-00185 Rome , Italy
- Center for Life Nano Science@Sapienza , Istituto Italiano di Tecnologia , Viale Regina, Elena 291 , 00161 Rome , Italy
| | - M A Ramos
- Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera , Universidad Autónoma de Madrid , E-28049 Madrid , Spain
| | - T Scopigno
- Dipartimento di Fisica , Universitá di Roma , La Sapienza , I-00185 Rome , Italy
- Center for Life Nano Science@Sapienza , Istituto Italiano di Tecnologia , Viale Regina, Elena 291 , 00161 Rome , Italy
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Low-temperature excess heat capacity in fresnoite glass and crystal. Sci Rep 2014; 4:6523. [PMID: 25283583 PMCID: PMC4185376 DOI: 10.1038/srep06523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 09/12/2014] [Indexed: 11/17/2022] Open
Abstract
The effect of thermal annealing on low-temperature excess heat capacity was investigated in fresnoite (Ba2TiSi2O8) glass. The amplitudes of the excess heat capacity decreased, and their positions shifted to a higher temperature by relaxation or crystallization. In particular, we revealed that the change in the excess heat capacity during transition from the glassy state to the crystalline state is relatively small compared with that of other oxides. Therefore, it is suggested that distribution of the excess vibrational density of states of the glass is similar to that of the corresponding crystal.
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Bayle M, Combe N, Sangeetha NM, Viau G, Carles R. Vibrational and electronic excitations in gold nanocrystals. NANOSCALE 2014; 6:9157-9165. [PMID: 24979073 DOI: 10.1039/c4nr02185a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An experimental analysis of all elementary excitations--phonons and electron-holes--in gold nanocrystals has been performed using plasmon resonance Raman scattering. Assemblies of monodisperse, single-crystalline gold nanoparticles, specific substrates and specific experimental configurations have been used. Three types of excitations are successively analyzed: collective quasi-acoustical vibrations of the particles (Lamb's modes), electron-hole excitations (creating the so-called "background" in surface-enhanced Raman scattering) and ensembles of atomic vibrations ("bulk" phonons). The experimental vibrational density of states extracted from the latter contribution is successfully compared with theoretical estimations performed using atomic simulations. The dominant role of surface atoms over the core ones on lattice dynamics is clearly demonstrated. Consequences on the thermodynamic properties of nanocrystals such as the decrease of the characteristic Debye temperature are also considered.
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Affiliation(s)
- Maxime Bayle
- Université de Toulouse, CEMES CNRS, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 4, France.
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