1
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Castelli F, Consolati G. Modelling Annihilation Properties of Positronium Confined in Nanoporous Materials: A Review. Int J Mol Sci 2024; 25:3692. [PMID: 38612506 PMCID: PMC11011886 DOI: 10.3390/ijms25073692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/19/2024] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
Positronium (Ps) is a valuable probe to investigate nanometric or sub-nanometric cavities in non-metallic materials, where Ps can be confined. Accessible experimental measurements concern the lifetime of trapped Ps, which is largely influenced by pick-off processes, depending on the size of the cavity as well as on the density of the electrons belonging to the surface of the host trap. Another relevant physical quantity is the contact density, that is the electron density at the positron position, which is usually found to be well below the vacuum value. Here, we review the principal models that have been formulated to account and explain for these physical properties of confined Ps. Starting with models, treating Ps as a single particle formulated essentially to study pick-off, we go on to describe more refined two-particle models because a two-body model is the simplest approach able to describe any change in the contact density, observed in many materials. Finally, we consider a theory of Ps annihilation in nanometric voids in which the exchange correlations between the electron of Ps and the outer electrons play a fundamental role. This theory is not usually taken into account in the literature, but it has to be considered for a correct theory of pick-off annihilation processes.
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Affiliation(s)
- Fabrizio Castelli
- Department of Physics “Aldo Pontremoli”, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Via Celoria 16, 20133 Milano, Italy;
| | - Giovanni Consolati
- Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Via Celoria 16, 20133 Milano, Italy;
- Department of Aerospace Science and Technology, Politecnico di Milano, Via La Masa 34, 20156 Milano, Italy
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2
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Shchedrina N, Cavillon M, Ari J, Ollier N, Lancry M. Impact of Glass Free Volume on Femtosecond Laser-Written Nanograting Formation in Silica Glass. MATERIALS (BASEL, SWITZERLAND) 2024; 17:502. [PMID: 38276441 PMCID: PMC10820044 DOI: 10.3390/ma17020502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 01/14/2024] [Accepted: 01/18/2024] [Indexed: 01/27/2024]
Abstract
In this study, we investigate the effects of densification through high pressure and temperature (up to 5 GPa, 1000 °C) in the making of nanogratings in pure silica glass, inscribed with femtosecond laser. The latter were monitored through retardance measurements using polarized optical microscopy, and their internal structure was observed under scanning electron microscopy. We reveal the difficulty in making nanogratings in densified silica glasses. Based on this observation, we propose that free volume may be a key precursor to initiate nanograting formation.
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Affiliation(s)
- Nadezhda Shchedrina
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, Avenue des Sciences, 91400 Orsay, France; (M.C.); (J.A.)
- Laboratoire des Solides Irradiés, École Polytechnique-CEA-CNRS, 91128 Palaiseau Cedex, France;
| | - Maxime Cavillon
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, Avenue des Sciences, 91400 Orsay, France; (M.C.); (J.A.)
| | - Julien Ari
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, Avenue des Sciences, 91400 Orsay, France; (M.C.); (J.A.)
| | - Nadège Ollier
- Laboratoire des Solides Irradiés, École Polytechnique-CEA-CNRS, 91128 Palaiseau Cedex, France;
| | - Matthieu Lancry
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, Avenue des Sciences, 91400 Orsay, France; (M.C.); (J.A.)
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3
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Ollier N, Reghioua I, Cavani O, Mobasher M, Alessi A, le Floch S, Skuja L. Probing densified silica glass structure by molecular oxygen and E' center formation under electron irradiation. Sci Rep 2023; 13:13657. [PMID: 37607961 PMCID: PMC10444884 DOI: 10.1038/s41598-023-40270-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 08/08/2023] [Indexed: 08/24/2023] Open
Abstract
This study aims to learn more about the structure of densified silica with focus on the metamict-like silica phase (density = 2.26 g/cm3) by examining the formation of E' point defects and interstitial molecular oxygen O2 by 2.5 MeV electron irradiation. High-dose (11 GGy) irradiation creates a metamict-like phase and a large amount of interstitial O2, which is destroyed upon subsequent additional lower-dose electron irradiation. The O2 cathodoluminescence (CL) data indicate that the formation of O2 from peroxy linkages Si-O-O-Si in silica network is strongly dependent on the intertetrahedral void sizes. The position and shape of the O2 emission line support the idea that the configuration of these voids in metamict phase is close to that of non-densified silica. Moreover, data support the strong correlation between the formation of 3-membered rings of Si-O bonds and E'-centers when silica density increases from 2.20 to 2.26 g/cm3.
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Affiliation(s)
- N Ollier
- Laboratoire des Solides Irradiés Ecole Polytechnique, CNRS, CEA\DRF\IRAMIS, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France.
| | - I Reghioua
- Laboratoire des Solides Irradiés Ecole Polytechnique, CNRS, CEA\DRF\IRAMIS, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France
| | - O Cavani
- Laboratoire des Solides Irradiés Ecole Polytechnique, CNRS, CEA\DRF\IRAMIS, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France
| | - M Mobasher
- Laboratoire des Solides Irradiés Ecole Polytechnique, CNRS, CEA\DRF\IRAMIS, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France
| | - A Alessi
- Laboratoire des Solides Irradiés Ecole Polytechnique, CNRS, CEA\DRF\IRAMIS, Institut Polytechnique de Paris, 91128, Palaiseau Cedex, France
| | - S le Floch
- Institut Lumière Matière, Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, 69622, Villeurbanne, France
| | - L Skuja
- Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., Riga, 1063, Latvia
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4
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Densification in transparent SiO 2 glasses prepared by spark plasma sintering. Sci Rep 2022; 12:14761. [PMID: 36042246 PMCID: PMC9427799 DOI: 10.1038/s41598-022-18892-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/22/2022] [Indexed: 11/09/2022] Open
Abstract
Recently, spark plasma sintering (SPS) has become an attractive method for the preparation of solid-state ceramics. As SPS is a pressure-assisted low-temperature process, it is important to examine the effects of temperature and pressure on the structural properties of the prepared samples. In the present study, we examined the correlation between the preparation conditions and the physical and structural properties of SiO2 glasses prepared by SPS. Compared with the conventional SiO2 glass, the SPS-SiO2 glasses exhibit a higher density and elastic modulus, but a lower-height first sharp diffraction peak of the X-ray total structure factor. Micro-Raman and micro-IR spectra suggest the formation of heterogeneous regions at the interface between the SiO2 powders and graphite die. Considering the defect formation observed in optical absorption spectra, reduction reaction mainly affects the densification of SPS-SiO2 glass. Hence, the reaction at the interface is important for tailoring the structure and physical properties of solid-state materials prepared by the SPS technique.
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5
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Lee SK, Lee AC, Kweon JJ. Probing Medium-Range Order in Oxide Glasses at High Pressure. J Phys Chem Lett 2021; 12:1330-1338. [PMID: 33502857 DOI: 10.1021/acs.jpclett.1c00055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Densification in glassy networks has traditionally been described in terms of short-range structures, such as how atoms are coordinated and how the coordination polyhedron is linked in the second coordination environment. While changes in medium-range structures beyond the second coordination shells may play an important role, experimental verification of the densification beyond short-range structures is among the remaining challenges in the physical sciences. Here, a correlation NMR experiment for prototypical borate glasses under compression up to 9 GPa offers insights into the pressure-induced evolution of proximity among cations on a medium-range scale. Whereas amorphous networks at ambient pressure may favor the formation of medium-range clusters consisting primarily of similar coordination species, such segregation between distinct coordination environments tends to decrease with increasing pressure, promoting a more homogeneous distribution of dissimilar structural units. Together with an increase in the average coordination number, densification of glass accompanies a preferential rearrangement toward a random distribution, which may increase the configurational entropy. The results highlight the direct link between the pressure-induced increase in medium-range disorder and the densification of glasses under extreme compression.
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Lee SK, Mun KY, Kim YH, Lhee J, Okuchi T, Lin JF. Degree of Permanent Densification in Oxide Glasses upon Extreme Compression up to 24 GPa at Room Temperature. J Phys Chem Lett 2020; 11:2917-2924. [PMID: 32223166 DOI: 10.1021/acs.jpclett.0c00709] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
During the decompression of plastically deformed glasses at room temperature, some aspects of irreversible densification may be preserved. This densification has been primarily attributed to topological changes in glass networks. The changes in short-range structures like cation coordination numbers are often assumed to be relaxed upon decompression. Here the NMR results for aluminosilicate glass upon permanent densification up to 24 GPa reveal noticeable changes in the Al coordination number under pressure conditions as low as ∼6 GPa. A drastic increase in the highly coordinated Al fraction is evident over only a relatively narrow pressure range of up to ∼12 GPa, above which the coordination change becomes negligible up to 24 GPa. In contrast, Si coordination environments do not change, highlighting preferential coordination transformation during deformation. The observed trend in the coordination environment shows a remarkable similarity to the pressure-induced changes in the residual glass density, yielding a predictive relationship between the irreversible densification and the detailed structures under extreme compression. The results open a way to access the nature of plastic deformation in complex glasses at room temperature.
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Affiliation(s)
- Sung Keun Lee
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea
- Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Kwan Young Mun
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea
| | - Yong-Hyun Kim
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea
| | - Juho Lhee
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea
| | - Takuo Okuchi
- Institute for Planetary Materials, Okayama University, Misasa 682-0193, Japan
| | - Jung-Fu Lin
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, United States
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7
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Tanzi Marlotti G, Consolati G, Castelli F. Formal calculation of exchange correlation effects on annihilation lifetimes of positronium confined in small cavities. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:025602. [PMID: 31550695 DOI: 10.1088/1361-648x/ab477e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Positronium atoms (Ps) are widely used as a probe to characterize voids or vacancies in non-metallic materials. The annihilation lifetime of trapped Ps is strongly modified by pickoff, depending on the cavity size and on the appropriate external electron density. The connection between these material characteristics and Ps annihilation lifetimes is usually based on models that do not consider the requirements of full electron indistinguishability, that must be taken into account for a correct description of pickoff annihilation processes. In this report, we provide a formal theoretical framework in which exchange correlation effects between confined Ps and surrounding electrons are introduced in a natural way, giving a clear and versatile picture of the various contributions to pickoff annihilation. Moreover, our results provide a simple explanation of the lowering of the contact density (the Ps-electron density at the positron position) as a direct consequence of the electrons indistinguishability, at variance with previous interpretation based on spatial deformations of Ps wavefunction. Calculations are performed within the 'symmetry adapted perturbation theory' approach, and the results are compared with available experimental data on Ps lifetimes for polymers and molecular solids. Finally, our analysis gives a formal justification to the approximations involved in early models based on the well known Tao-Eldrup approach, and gives a simple interpretation of Ps properties in subnanometric voids.
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Affiliation(s)
- G Tanzi Marlotti
- Department of Physics 'Aldo Pontremoli', Università degli Studi di Milano, via Celoria 16 I-20133 Milano, Italy
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Cornet A, Martinet C, Martinez V, de Ligny D. Evidence of polyamorphic transitions during densified SiO2 glass annealing. J Chem Phys 2019; 151:164502. [DOI: 10.1063/1.5121534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Antoine Cornet
- Institut Lumière Matière, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, F-69622 Villeurbanne, France
| | - Christine Martinet
- Institut Lumière Matière, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, F-69622 Villeurbanne, France
| | - Valérie Martinez
- Institut Lumière Matière, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, F-69622 Villeurbanne, France
| | - Dominique de Ligny
- Department of Materials Science, Glass and Ceramics, University Erlangen-Nürnberg, Martensstra., D-91058 Erlangen, Germany
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9
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A Correlation Study of Subnanoscopic Free Volume and Thermo-physical Properties of Modified Borosilicate Glasses with Progressive Substitution of B2O3 by Al2O3. J Inorg Organomet Polym Mater 2017. [DOI: 10.1007/s10904-017-0674-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Mantisi B, Kermouche G, Barthel E, Tanguy A. Impact of pressure on plastic yield in amorphous solids with open structure. Phys Rev E 2016; 93:033001. [PMID: 27078435 DOI: 10.1103/physreve.93.033001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Indexed: 11/07/2022]
Abstract
Plasticity in amorphous silica is unusual: The yield stress decreases with hydrostatic pressure, in contrast to the Mohr-Coulomb response commonly found in more compact materials such as bulk metallic glasses. To better understand this response, we have carried out molecular dynamics simulations of plastic response in a model glass with open structure. The simulations reproduce the anomalous dependence of yield stress with pressure and also correctly predict that the plastic response turns to normal once the material has been fully compacted. We also show that the overall shape of the yield surface is consistent with a quadratic behavior predicted assuming local buckling of the structure, a point of view that fits well into the present understanding of the deformation mechanisms of amorphous silica. The results also confirm that free volume is an adequate internal variable for a continuum scale description of the plastic response of amorphous silica. Finally, we also investigate the long-range correlations between rearrangement events. We find that strong intermittency is observed when the structure remains open, while compaction results in more homogeneous rearrangements. These findings are in agreement with recent results on the effect of compression on the middle range order in silicate glasses and also suggest that the well-known volume recovery of densified silica at relatively low temperatures is in fact a form of aging.
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Affiliation(s)
- B Mantisi
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités UPMC, BP 121, 4 Place Jussieu, 75252 Paris Cedex 05, France
| | - G Kermouche
- Materials Sciences and Structures Division, Ecole des Mines de Saint-Etienne, LGF UMR No. 5307, CNRS, 158 Cours Fauriel, 42023 Saint-Etienne Cedex 2, France
| | - E Barthel
- École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris ParisTech, PSL Research University, Sciences et Ingénierie de la matière Molle, CNRS UMR No. 7615, 10 Rue Vauquelin, F-75231 Paris Cedex 05, France and Sorbonne-Universités, UPMC Université Paris 06, SIMM, 10 Rue Vauquelin, 75231 Paris Cedex 05, France
| | - A Tanguy
- Université de Lyon, LaMCoS, INSA-Lyon, CNRS UMR5259, F-69621, France
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11
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Masuno A, Nishiyama N, Sato F, Kitamura N, Taniguchi T, Inoue H. Higher refractive index and lower wavelength dispersion of SiO 2 glass by structural ordering evolution via densification at a higher temperature. RSC Adv 2016. [DOI: 10.1039/c5ra25106k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Silica glasses permanently densified at high temperatures show unexpected increase of both the refractive index and the Abbe number. Glasses densified at a higher temperature underwent homogeneous evolution of their intermediate structural ordering.
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Affiliation(s)
- A. Masuno
- Institute of Industrial Science
- The University of Tokyo
- Tokyo 153-8505
- Japan
| | - N. Nishiyama
- Deutsches Elektronen-Synchrotron (DESY)
- 22607 Hamburg
- Germany
- PRESTO
- Japan Science and Technology Agency
| | - F. Sato
- Nippon Electric Glass Co., Ltd
- Shiga 520-8639
- Japan
| | - N. Kitamura
- National Institute of Advanced Industrial Science and Technology
- Osaka 563-8577
- Japan
| | - T. Taniguchi
- National Institute for Materials Science
- Tsukuba 305-0044
- Japan
| | - H. Inoue
- Institute of Industrial Science
- The University of Tokyo
- Tokyo 153-8505
- Japan
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12
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Tian KV, Yang B, Yue Y, Bowron DT, Mayers J, Donnan RS, Dobó-Nagy C, Nicholson JW, Fang DC, Greer AL, Chass GA, Greaves GN. Atomic and vibrational origins of mechanical toughness in bioactive cement during setting. Nat Commun 2015; 6:8631. [PMID: 26548704 PMCID: PMC4659834 DOI: 10.1038/ncomms9631] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/14/2015] [Indexed: 11/08/2022] Open
Abstract
Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass-polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials.
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Affiliation(s)
- Kun V. Tian
- Department of Oral Diagnostics, Faculty of Dentistry, Semmelweis University, Budapest 1088, Hungary
| | - Bin Yang
- Department of Electronic and Electrical Engineering, University of Chester, Thornton Science Park, Chester CH2 4NU, UK
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK
| | - Yuanzheng Yue
- Laboratory of Extreme Glassy State, State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg, Denmark
| | - Daniel T. Bowron
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Jerry Mayers
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Robert S. Donnan
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK
| | - Csaba Dobó-Nagy
- Department of Oral Diagnostics, Faculty of Dentistry, Semmelweis University, Budapest 1088, Hungary
| | - John W. Nicholson
- School of Sport, Health and Applied Science, St Mary's University, London TW1 4SX, UK
| | - De-Cai Fang
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - A. Lindsay Greer
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
| | - Gregory A. Chass
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - G. Neville Greaves
- Laboratory of Extreme Glassy State, State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- Department of Physics, Institute of Mathematics, Physics and Computer Science, Aberystwyth University, Aberystwyth SY23 3BZ, UK
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13
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Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression. Sci Rep 2015; 5:15343. [PMID: 26469314 PMCID: PMC4606793 DOI: 10.1038/srep15343] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/23/2015] [Indexed: 11/16/2022] Open
Abstract
Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young’s modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.
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