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Fu W, Yin J, Cao H, Zhou Z, Zhang J, Fu J, Warner JH, Wang C, Jia X, Greaves GN, Cheetham AK. Non-Blinking Luminescence from Charged Single Graphene Quantum Dots. Adv Mater 2023; 35:e2304074. [PMID: 37395476 DOI: 10.1002/adma.202304074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/24/2023] [Accepted: 06/26/2023] [Indexed: 07/04/2023]
Abstract
Photoluminescence blinking behavior from single quantum dots under steady illumination is an important but controversial topic. Its occurrence has impeded the use of single quantum dots in bioimaging. Different mechanisms have been proposed to account for it, although controversial, the most important of which is the non-radiative Auger recombination mechanism whereby photocharging of quantum dots can lead to the blinking phenomenon. Here, the singly charged trion, which maintains photon emission, including radiative recombination and non-radiative Auger recombination, leads to fluorescence non-blinking which is observed in photocharged single graphene quantum dots (GQDs). This phenomenon can be explained in terms of different energy levels in the GQDs, caused by various oxygen-containing functional groups in the single GQDs. The suppressed blinking is due to the filling of trap sites owing to a Coulomb blockade. These results provide a profound understanding of the special optical properties of GQDs, affording a reference for further in-depth research.
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Affiliation(s)
- Wei Fu
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Jiefu Yin
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Huaqiang Cao
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhongfu Zhou
- State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, Shanghai, 200072, China
| | - Junying Zhang
- School of Physics, Beihang University, Beijing, 100191, China
| | - Jingjing Fu
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jamie H Warner
- Department of Mechanical Engineering, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, TX, 78712, USA
| | - Cheng Wang
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Xiaofang Jia
- School of Physics, Beihang University, Beijing, 100191, China
| | - G Neville Greaves
- Department of Physics, Aberystwyth University, Aberystwyth, SY23 3BZ, UK
- Department of Materials Science and Metallurgy, The University of Cambridge, Cambridge, CB3 0FS, UK
| | - Anthony K Cheetham
- Department of Materials Science and Metallurgy, The University of Cambridge, Cambridge, CB3 0FS, UK
- Materials Research Laboratory, University of California, Santa Barbara, CA, 93106, USA
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2
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Liu H, Chen W, Pan R, Shan Z, Qiao A, Drewitt JWE, Hennet L, Jahn S, Langstaff DP, Chass GA, Tao H, Yue Y, Greaves GN. From Molten Calcium Aluminates through Phase Transitions to Cement Phases. Adv Sci (Weinh) 2020; 7:1902209. [PMID: 31993291 PMCID: PMC6974954 DOI: 10.1002/advs.201902209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/17/2019] [Indexed: 06/10/2023]
Abstract
Crystalline calcium aluminates are a critical setting agent in cement. To date, few have explored the microscopic and dynamic mechanism of the transitions from molten aluminate liquids, through the supercooled state to glassy and crystalline phases, during cement clinker production. Herein, the first in situ measurements of viscosity and density are reported across all the principal molten phases, relevant to their eventual crystalline structures. Bulk atomistic computer simulations confirm that thermophysical properties scale with the evolution of network substructures interpenetrating melts on the nanoscale. It is demonstrated that the glass transition temperature (T g) follows the eutectic profile of the liquidus temperature (T m), coinciding with the melting zone in cement production. The viscosity has been uniquely charted over 14 decades for each calcium-aluminate phase, projecting and justifying the different temperature zones used in cement manufacture. The fragile-strong phase transitions are revealed across all supercooled phases coinciding with heterogeneous nucleation close to 1.2T g, where sintering and quenching occur in industrial-scale cement processing.
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Affiliation(s)
- Hao Liu
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
- Department of Chemistry and BioscienceAalborg UniversityDK‐9220AalborgDenmark
| | - Wenlin Chen
- Department of PhysicsAberystwyth UniversityPenglais CampusAberystwythCeredigionSY23 3BZUK
| | - Ruikun Pan
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
- School of Materials Science and EngineeringHubei UniversityWuhan430062China
| | - Zhitao Shan
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
| | - Ang Qiao
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
- Department of Chemistry and BioscienceAalborg UniversityDK‐9220AalborgDenmark
| | - James W. E. Drewitt
- School of Earth SciencesUniversity of BristolWills Memorial BuildingBristolBS8 1RJUK
| | - Louis Hennet
- Conditions Extrêmes et Matériaux: Haute Température et IrradiationUniversity d'Orléans45071Orléans cedex 2France
| | - Sandro Jahn
- Institute of Geology and MineralogyUniversity of Cologne50674CologneGermany
| | - David P. Langstaff
- Department of PhysicsAberystwyth UniversityPenglais CampusAberystwythCeredigionSY23 3BZUK
| | - Gregory A. Chass
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
- Department of ChemistryThe University of Hong KongHong KongChina
- Department of ChemistryMcMaster UniversityHamiltonOntarioL8S 4M1Canada
- Department of ChemistryLa Sapienza University of RomePiazzale Aldo Moro00185RomaItaly
| | - Haizheng Tao
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
| | - Yuanzheng Yue
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
- Department of Chemistry and BioscienceAalborg UniversityDK‐9220AalborgDenmark
- School of Materials Science and EngineeringQilu University of TechnologyJinan250353China
| | - G. Neville Greaves
- State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan430070China
- Department of PhysicsAberystwyth UniversityPenglais CampusAberystwythCeredigionSY23 3BZUK
- Department of Materials Science and MetallurgyUniversity of CambridgeCambridgeCB3 0FSUK
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3
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Abstract
In the version of this Review Article originally published, parentheses were misplaced and the longitudinal and transverse speeds were inverted in two expressions for Poisson's ratio in Box 2; the expressions should have read, respectively, ν = (3B/G - 2)/(6B/G + 2) and ν = [½(Vl/Vt)2 - 1]/[(Vl/Vt)2 - 1].
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Affiliation(s)
- G N Greaves
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, UK.
- Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth, SY23 3BZ, UK.
| | - A L Greer
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, UK
| | - R S Lakes
- Department of Engineering Physics, Department of Materials Science, University of Wisconsin-Madison, Wisconsin, 53706-1687, USA
| | - T Rouxel
- Applied Mechanics Laboratory, LARMAUR ERL-CNRS 6274, Université Rennes 1, 35042, Rennes cedex, France
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Chen W, Ross NL, Greaves GN. DFT study of the effect of pressure on framework materials including ZIF-8 and inorganic zeolites. Acta Crystallogr A Found Adv 2018. [DOI: 10.1107/s0108767318097635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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5
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Wondraczek L, Pan Z, Palenta T, Erlebach A, Misture ST, Sierka M, Micoulaut M, Hoppe U, Deubener J, Greaves GN. Kinetics of Decelerated Melting. Adv Sci (Weinh) 2018; 5:1700850. [PMID: 29876211 PMCID: PMC5979640 DOI: 10.1002/advs.201700850] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/11/2018] [Indexed: 05/22/2023]
Abstract
Melting presents one of the most prominent phenomena in condensed matter science. Its microscopic understanding, however, is still fragmented, ranging from simplistic theory to the observation of melting point depressions. Here, a multimethod experimental approach is combined with computational simulation to study the microscopic mechanism of melting between these two extremes. Crystalline structures are exploited in which melting occurs into a metastable liquid close to its glass transition temperature. The associated sluggish dynamics concur with real-time observation of homogeneous melting. In-depth information on the structural signature is obtained from various independent spectroscopic and scattering methods, revealing a step-wise nature of the transition before reaching the liquid state. A kinetic model is derived in which the first reaction step is promoted by local instability events, and the second is driven by diffusive mobility. Computational simulation provides further confirmation for the sequential reaction steps and for the details of the associated structural dynamics. The successful quantitative modeling of the low-temperature decelerated melting of zeolite crystals, reconciling homogeneous with heterogeneous processes, should serve as a platform for understanding the inherent instability of other zeolitic structures, as well as the prolific and more complex nanoporous metal-organic frameworks.
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Affiliation(s)
- Lothar Wondraczek
- Otto Schott Institute of Materials ResearchUniversity of Jena07743JenaGermany
- Center of Energy and Environmental ChemistryUniversity of Jena07743JenaGermany
| | - Zhiwen Pan
- Otto Schott Institute of Materials ResearchUniversity of Jena07743JenaGermany
- Center of Energy and Environmental ChemistryUniversity of Jena07743JenaGermany
| | - Theresia Palenta
- Otto Schott Institute of Materials ResearchUniversity of Jena07743JenaGermany
- Center of Energy and Environmental ChemistryUniversity of Jena07743JenaGermany
| | - Andreas Erlebach
- Otto Schott Institute of Materials ResearchUniversity of Jena07743JenaGermany
| | | | - Marek Sierka
- Otto Schott Institute of Materials ResearchUniversity of Jena07743JenaGermany
| | - Matthieu Micoulaut
- Physique Théorique de la Matière CondenséeParis Sorbonne Universités – UPMC75252ParisFrance
| | - Uwe Hoppe
- Institute of PhysicsRostock University18059RostockGermany
| | - Joachim Deubener
- Institute of Non‐Metallic MaterialsClausthal University of Technology38678Clausthal‐ZellerfeldGermany
| | - G. Neville Greaves
- Department of Materials Science and MetallurgyUniversity of CambridgeCB3 0FSCambridgeUK
- Department of PhysicsAberystwyth UniversitySY23 3BZAberystwythUK
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6
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Qiao A, Bennett TD, Tao H, Krajnc A, Mali G, Doherty CM, Thornton AW, Mauro JC, Greaves GN, Yue Y. A metal-organic framework with ultrahigh glass-forming ability. Sci Adv 2018; 4:eaao6827. [PMID: 29536040 PMCID: PMC5844704 DOI: 10.1126/sciadv.aao6827] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 02/01/2018] [Indexed: 05/26/2023]
Abstract
Glass-forming ability (GFA) is the ability of a liquid to avoid crystallization during cooling. Metal-organic frameworks (MOFs) are a new class of glass formers (1-3), with hitherto unknown dynamic and thermodynamic properties. We report the discovery of a new series of tetrahedral glass systems, zeolitic imidazolate framework-62 (ZIF-62) [Zn(Im2-x bIm x )], which have ultrahigh GFA, superior to any other known glass formers. This ultrahigh GFA is evidenced by a high viscosity η (105 Pa·s) at the melting temperature Tm, a large crystal-glass network density deficit (Δρ/ρg)network, no crystallization in supercooled region on laboratory time scales, a low fragility (m = 23), an extremely high Poisson's ratio (ν = 0.45), and the highest Tg/Tm ratio (0.84) ever reported. Tm and Tg both increase with benzimidazolate (bIm) content but retain the same ultrahigh Tg/Tm ratio, owing to high steric hindrance and frustrated network dynamics and also to the unusually low enthalpy and entropy typical of the soft and flexible nature of MOFs. On the basis of these versatile properties, we explain the exceptional GFA of the ZIF-62 system.
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Affiliation(s)
- Ang Qiao
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Thomas D. Bennett
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK
| | - Haizheng Tao
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Andraž Krajnc
- Department of Inorganic Chemistry and Technology, National Institute of Chemistry, 1001 Ljubljana, Slovenia
| | - Gregor Mali
- Department of Inorganic Chemistry and Technology, National Institute of Chemistry, 1001 Ljubljana, Slovenia
| | - Cara M. Doherty
- Future Industries, Commonwealth Scientific and Industrial Research Organisation, Clayton South, Victoria 3168, Australia
| | - Aaron W. Thornton
- Future Industries, Commonwealth Scientific and Industrial Research Organisation, Clayton South, Victoria 3168, Australia
| | - John C. Mauro
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- School of Materials Science and Engineering, Qilu University of Technology, Jinan 250353, China
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - G. Neville Greaves
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK
- Department of Physics, Aberystwyth University, Aberystwyth SY23 3BZ, UK
| | - Yuanzheng Yue
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
- School of Materials Science and Engineering, Qilu University of Technology, Jinan 250353, China
- Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg, Denmark
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7
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Chen H, Zhou Z, Greaves GN, Nigar S, Cao H, Zhao T, Lu X. Pt nanoparticles decorated rose-like Bi2O2CO3 configurations for efficient photocatalytic removal of water organic pollutants. RSC Adv 2018; 8:914-920. [PMID: 35538986 PMCID: PMC9076944 DOI: 10.1039/c7ra12236e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 12/08/2017] [Indexed: 01/29/2023] Open
Abstract
Pt nanoparticles decorated with rose-like Bi2O2CO3 configurations were synthesized via a simple photoreduction method at room temperature.
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Affiliation(s)
- Huijuan Chen
- School of Material Science and Engineering
- Shanghai University
- Shanghai 200444
- PR China
| | - Zhongfu Zhou
- State Key Laboratory of Advanced Special Steel
- Shanghai University
- Shanghai 200072
- PR China
- Key Laboratory of Material Microstructures
| | - G. Neville Greaves
- Department of Physics
- Aberystwyth University
- Aberystwyth SY23 3BZ
- UK
- State Key Laboratory of Silicate Materials for Architectures
| | - Salma Nigar
- School of Material Science and Engineering
- Shanghai University
- Shanghai 200444
- PR China
| | - Huaqiang Cao
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- PR China
| | - Tingkai Zhao
- State Key Laboratory of Solidification Processing
- School of Materials Science and Engineering
- Northwestern Polytechnical University
- Xi'an 710072
- PR China
| | - Xionggang Lu
- State Key Laboratory of Advanced Special Steel
- Shanghai University
- Shanghai 200072
- PR China
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8
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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9
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Palenta T, Fuhrmann S, Greaves GN, Schwieger W, Wondraczek L. Thermal collapse and hierarchy of polymorphs in a faujasite-type zeolite and its analogous melt-quenched glass. J Chem Phys 2015; 142:084503. [PMID: 25725741 DOI: 10.1063/1.4913240] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We examine the route of structural collapse and re-crystallization of faujasite-type (Na,K)-LSX zeolite. As the first step, a rather stable amorphous high density phase HDAcollapse is generated through an order-disorder transition from the original zeolite via a low density phase LDAcollapse, at around 790 °C. We find that the overall amorphization is driven by an increase in the bond angle distribution within T-O-T and a change in ring statistics to 6-membered TO4 (T = Si(4+), Al(3+)) rings at the expense of 4-membered rings. The HDAamorph transforms into crystalline nepheline, though, through an intermediate metastable carnegieite phase. In comparison, the melt-derived glass of similar composition, HDAMQ, crystallizes directly into the nepheline phase without the occurrence of intermediate carnegieite. This is attributed to the higher structural order of the faujasite-derived HDAcollapse which prefers the re-crystallization into the highly symmetric carnegieite phase before transformation into nepheline with lower symmetry.
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Affiliation(s)
- Theresia Palenta
- Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany
| | - Sindy Fuhrmann
- Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany
| | - G Neville Greaves
- Department of Materials Science and Metallurgy, University of Cambridge, CB3 0FS Cambridge, United Kingdom
| | - Wilhelm Schwieger
- Department of Chemical and Bioengineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany
| | - Lothar Wondraczek
- Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany
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Hou J, Li Y, Mao M, Yue Y, Greaves GN, Zhao X. Full solar spectrum light driven thermocatalysis with extremely high efficiency on nanostructured Ce ion substituted OMS-2 catalyst for VOCs purification. Nanoscale 2015; 7:2633-2640. [PMID: 25581777 DOI: 10.1039/c4nr06410k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The nanostructured Ce ion substituted cryptomelane-type octahedral molecular sieve (OMS-2) catalyst exhibits strong absorption in the entire solar spectrum region. The Ce ion substituted OMS-2 catalyst can efficiently transform the absorbed solar energy to thermal energy, resulting in a considerable increase of temperature. By combining the efficient photothermal conversion and thermocatalytic activity of the Ce ion substituted OMS-2 catalyst, we carried out full solar spectrum, visible-infrared, and infrared light driven catalysis with extremely high efficiency. Under the irradiation of full solar spectrum, visible-infrared, and infrared light, the Ce ion substituted OMS-2 catalyst exhibits extremely high catalytic activity and excellent durability for the oxidation of volatile organic pollutants such as benzene, toluene, and acetone. Based on the experimental evidence, we propose a novel mechanism of solar light driven thermocatalysis for the Ce ion substituted OMS-2 catalyst. The reason why the Ce ion substituted OMS-2 catalyst exhibits much higher catalytic activity than pure OMS-2 and CeO2/OMS-2 nano composite under the full solar spectrum irradiation is discussed.
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Affiliation(s)
- Jingtao Hou
- State Key Laboratory of Silicate Materials for Architectures (Wuhan University of Technology), 122 Luoshi Road, Wuhan 430070, P. R. China.
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11
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Langstaff D, Gunn M, Greaves GN, Marsing A, Kargl F. Aerodynamic levitator furnace for measuring thermophysical properties of refractory liquids. Rev Sci Instrum 2013; 84:124901. [PMID: 24387452 DOI: 10.1063/1.4832115] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The development of novel contactless aerodynamic laser heated levitation techniques is reported that enable thermophysical properties of refractory liquids to be measured in situ in the solid, liquid, and supercooled liquid state and demonstrated here for alumina. Starting with polished crystalline ruby spheres, we show how, by accurately measuring the changing radius, the known density in the solid state can be reproduced from room temperature to the melting point at 2323 K. Once molten, by coupling the floating liquid drop to acoustic oscillations via the levitating gas, the mechanical resonance and damping of the liquid can be measured precisely with high-speed high-resolution shadow cast imaging. The resonance frequency relates to the surface tension, the decay constant to the viscosity, and the ellipsoidal size and shape of the levitating drop to the density. This unique instrumentation enables these related thermophysical properties to be recorded in situ over the entire liquid and supercooled range of alumina, from the boiling point at 3240 K, until spontaneous crystallization occurs around 1860 K, almost 500 below the melting point. We believe that the utility that this unique instrumentation provides will be applicable to studying these important properties in many other high temperature liquids.
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Affiliation(s)
- D Langstaff
- Centre for Advanced Functional Materials and Devices, Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, United Kingdom
| | - M Gunn
- Centre for Advanced Functional Materials and Devices, Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, United Kingdom
| | - G N Greaves
- Centre for Advanced Functional Materials and Devices, Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, United Kingdom
| | - A Marsing
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - F Kargl
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
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12
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McMillan PF, Greaves GN, Wilson M, Wilding MC, Daisenberger D. Polyamorphism and Liquid-Liquid Phase Transitions in Amorphous Silicon and Supercooled Al 2O 3-Y 2O 3Liquids. Liquid Polymorphism 2013. [DOI: 10.1002/9781118540350.ch12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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13
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Abstract
This article explores Poisson's ratio, starting with the controversy concerning its magnitude and uniqueness in the context of the molecular and continuum hypotheses competing in the development of elasticity theory in the nineteenth century, moving on to its place in the development of materials science and engineering in the twentieth century, and concluding with its recent re-emergence as a universal metric for the mechanical performance of materials on any length scale. During these episodes France lost its scientific pre-eminence as paradigms switched from mathematical to observational, and accurate experiments became the prerequisite for scientific advance. The emergence of the engineering of metals followed, and subsequently the invention of composites-both somewhat separated from the discovery of quantum mechanics and crystallography, and illustrating the bifurcation of technology and science. Nowadays disciplines are reconnecting in the face of new scientific demands. During the past two centuries, though, the shape versus volume concept embedded in Poisson's ratio has remained invariant, but its application has exploded from its origins in describing the elastic response of solids and liquids, into areas such as materials with negative Poisson's ratio, brittleness, glass formation, and a re-evaluation of traditional materials. Moreover, the two contentious hypotheses have been reconciled in their complementarity within the hierarchical structure of materials and through computational modelling.
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Affiliation(s)
- G. Neville Greaves
- Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, UK
- Institute for Materials Physics in Space, German Aerospace, 51147 Cologne, Germany
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14
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Abstract
In comparing a material's resistance to distort under mechanical load rather than to alter in volume, Poisson's ratio offers the fundamental metric by which to compare the performance of any material when strained elastically. The numerical limits are set by ½ and -1, between which all stable isotropic materials are found. With new experiments, computational methods and routes to materials synthesis, we assess what Poisson's ratio means in the contemporary understanding of the mechanical characteristics of modern materials. Central to these recent advances, we emphasize the significance of relationships outside the elastic limit between Poisson's ratio and densification, connectivity, ductility and the toughness of solids; and their association with the dynamic properties of the liquids from which they were condensed and into which they melt.
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Affiliation(s)
- G N Greaves
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK.
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15
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Greaves GN, Wilding MC, Hennet L, Langstaff D, Kargl F, Benmore CJ, Weber JKR. Comment on "liquid-liquid phase transition in supercooled yttria-alumina". Phys Rev Lett 2011; 106:119601-119602. [PMID: 21469907 DOI: 10.1103/physrevlett.106.119601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Revised: 06/01/2010] [Indexed: 05/30/2023]
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16
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Abstract
After over a quarter of a century, the doors of the world's first synchrotron radiation source have closed. Its contribution to materials science in the past and the future should not be underestimated.
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Affiliation(s)
- G N Greaves
- Institute of Mathematics and Physics, and Centre for Advanced Functional Materials and Devices, Aberystwyth University, Aberystwyth SY23 3BZ, UK.
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17
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Abstract
The phenomenology of zeolite collapse is outlined, drawing on recent synchrotron x-ray diffraction experiments and computer simulations of low density cage structures like zeolite A and zeolite Y. Attention is drawn to the importance of polyamorphism in destabilizing this type of microporous crystal and its role in order-disorder as well as amorphous-amorphous transitions, together with associated differences in entropy and density between polyamorphic phases and the precursor zeolite. Magic angle spinning NMR and inelastic x-ray scattering are used to highlight changes in structural order and mechanical rigidity between the starting zeolite and the final high density polyamorph. In conclusion, two-level systems detected with inelastic neutron scattering are described and their involvement in dictating the dynamics of the collapse of zeolitic cage structures.
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Affiliation(s)
- G Neville Greaves
- Centre for Advanced Functional Materials and Devices, Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth, Aberystwyth SY23 3BZ, UK
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18
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McMillan PF, Wilson M, Wilding MC, Daisenberger D, Mezouar M, Neville Greaves G. Polyamorphism and liquid-liquid phase transitions: challenges for experiment and theory. J Phys Condens Matter 2007; 19:415101. [PMID: 28192313 DOI: 10.1088/0953-8984/19/41/415101] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Phase transitions in the liquid state can be related to pressure-driven fluctuations developed in the density (i.e., the inverse of the molar volume; ρ = 1/V) or the entropy (S(T)) rather than by gradients in the chemical potential (μ(X), where X is the chemical composition). Experiments and liquid simulation studies now show that such transitions are likely to exist within systems with a wide range of chemical bonding types. The observations permit us to complete the trilogy of expected liquid state responses to changes in P and T as well as μ(X), as is the case among crystalline solids. Large structure-property changes occurring within non-ergodic amorphous solids as a function of P and T are also observed, that are generally termed 'polyamorphism'. The polyamorphic changes can map on to underlying density- or entropy-driven L-L transitions. Studying these phenomena poses challenges to experimental studies and liquid simulations. Experiments must be carried out over a wide P-T range for in situ structure-property determinations, often in a highly metastable regime. It is expected that L-L transitions often occur below the melting line, so that studies encounter competing crystallization phenomena. Simulation studies of liquid state polyamorphism must involve large system sizes, and examine system behaviour at low T into the deeply supercooled regime, with distance and timescales long enough to sample characteristic density/entropy fluctuations. These conditions must be achieved for systems with different bonding environments, that can change abruptly across the polyamorphic transitions. Here we discuss opportunities for future work using simulations combined with neutron and x-ray amorphous scattering techniques, with special reference to the behaviour of two polyamorphic systems: amorphous Si and supercooled Y2O3-Al2O3 liquids.
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Affiliation(s)
- Paul F McMillan
- Department of Chemistry and Materials Chemistry Centre, University College London, 20 Gordon Street, London WC1H 0AJ, UK. Davy-Faraday Research Laboratory, Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UK
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19
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Cristiglio V, Hennet L, Cuello GJ, Pozdnyakova I, Johnson MR, Fischer HE, Zanghi D, Van QV, Wilding MC, Greaves GN, Price DL. Structure of molten yttrium aluminates: a neutron diffraction study. J Phys Condens Matter 2007; 19:415105. [PMID: 28192317 DOI: 10.1088/0953-8984/19/41/415105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We used the aerodynamic levitation technique combined with CO2 laser heating to study the structure of liquid yttrium aluminates above their melting point with neutron diffraction. For various yttria contents, we determined the structure factors and corresponding pair correlation functions describing the short-range order in the liquids. In particular, we derived Al-O and Y-O bond distances and coordination numbers. Experimental data are compared with ab initio molecular dynamics, carried out using the VASP code where the interatomic forces are obtained from density functional theory. In particular, partial pair correlation functions have been calculated and are in relatively good agreement with the experimental observations.
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Affiliation(s)
- V Cristiglio
- Centre de Recherche sur les Matériaux à Haute Température, CNRS-CRMHT, 1d avenue de la Recherche Scientifique, 45071 Orléans cedex 2, France. Institut Laue-Langevin, 6 rue Jules Horowitz, BP48 Grenoble cedex 9, France
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20
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Hennet L, Pozdnyakova I, Bytchkov A, Price DL, Greaves GN, Wilding M, Fearn S, Martin CM, Thiaudière D, Bérar JF, Boudet N, Saboungi ML. Development of structural order during supercooling of a fragile oxide melt. J Chem Phys 2007; 126:074906. [PMID: 17328633 DOI: 10.1063/1.2646812] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors have studied the structural evolution of the fragile glass-forming liquid CaAl2O4 during supercooling from the stable liquid phase to the cold glass below Tg. The evolution is characterized by a sharpening of the first diffraction peak and a shortening of the average nearest-neighbor bond length around 1.25Tg, indicating an increase in the degree of both intermediate-range and short-range orders occurring close to the dynamical crossover temperature. The cooling curve developed a kink at this temperature, indicating a simultaneous change in thermodynamic properties.
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Affiliation(s)
- L Hennet
- Centre de Recherche sur les Matériaux à Haute Température, 45071 Orléans Cedex 2, France.
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Jones AR, Winter R, Greaves GN, Smith IH. 23Na, 29Si, and 13C MAS NMR Investigation of Glass-Forming Reactions between Na2CO3 and SiO2. J Phys Chem B 2005; 109:23154-61. [PMID: 16375277 DOI: 10.1021/jp053953y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The glass-forming reactions between sodium carbonate (Na2CO3) and silica (SiO2) have been investigated by 23Na, 29Si, and 13C magic-angle spinning (MAS) NMR spectroscopy. The multinuclear MAS NMR approach identifies and quantifies reaction products and intermediates, both glassy and crystalline. A series of powdered batches of initial composition Na2CO3.xSiO2 (x = 1, 2) corresponding to a sodium metasilicate (Na2SiO3) and sodium disilicate (Na2Si2O5) stoichiometry were investigated after periods of isothermal and nonisothermal heat treatments at different temperatures. Analysis of the 23Na quadrupolar coupling parameters has identified the early reaction product in all cases as crystalline Na2SiO3. In the nonisothermal experiment, this reaction is preceded by an early silica-rich melt phase formed around 850 degrees C. The early reactions are controlled by solid-state Na+ diffusion across the reaction zone in the grain interface layer. Crystalline Na2SiO3 precipitates in the interface layer, increasing its thickness between the Na2CO3 and the SiO2 grains and slowing down the rate of Na+ migration. This creates a secondary phase, which is temperature dependent. At low temperatures, where Na+ migration is impaired, the production of Na2SiO3 ceases and silica-richer phases are precipitated. In the case of the sodium disilicate batch, where excess SiO2 is present, a secondary reaction of Na2SiO3 with SiO2 forming a glassy phase is observed. A transient carbon-bearing phase has been identified by 13C NMR as a NaCO3- complex loosely bound to bridging oxygens in the silicate network at the SiO2 grain surface.
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Affiliation(s)
- Aled R Jones
- Materials Physics, University of Wales Aberystwyth, Penglais, Aberystwyth SY233BZ, Wales, United Kingdom
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22
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Abstract
High-resolution inelastic neutron scattering was used to identify major sources of low-frequency vibrations in zeolite crystals. Dispersed and nondispersed modes were found, both of which are prominent in the early stages of compressive amorphization but decline dramatically in strength once a glass of conventional density is created. By identifying the dispersed modes with the characteristic vibrations of the various secondary building units of zeolitic structures, the Boson peak, a characteristic of the glassy state, can be attributed to vibrations within connected rings of many different sizes. The nondispersed phonon features in zeolites, retained in the amorphized glass, were also replicated in silica. These modes are librational in origin and are responsible for destabilizing the microporous crystalline structure, for converting the resulting glass from a low- to a high-density phase, and for the associated changes in network topology that affect the Boson peak.
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Affiliation(s)
- G N Greaves
- Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth, SY23 3BZ, UK
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23
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Cernik RJ, Barnes P, Bushnell-Wye G, Dent AJ, Diakun GP, Flaherty JV, Greaves GN, Heeley EL, Helsby W, Jacques SDM, Kay J, Rayment T, Ryan A, Tang CC, Terrill NJ. The new materials processing beamline at the SRS Daresbury, MPW6.2. J Synchrotron Radiat 2004; 11:163-170. [PMID: 14960781 DOI: 10.1107/s0909049503027870] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Accepted: 12/03/2003] [Indexed: 05/24/2023]
Abstract
A new beamline (MPW6.2) has been designed and built for the study of materials during processing where three synchrotron techniques, SAXS, WAXS and XAS, are available simultaneously. It has been demonstrated that Rietveld refinable data can be collected from silicon SRM 640b over a 60 degrees range in a time scale of 1 s. The data have been refined to a chi(2) of 2.4, the peaks fitting best to a Pearson VII function or with fundamental parameters. The peak halfwidths have been found to be approximately constant at 0.06 degrees over a 120 degrees angular range indicating that the instrumental resolution function has matched its design specification. A quantitative comparison of data sets collected on the same isotactic polypropylene system on MPW6.2 and DUBBLE at the ESRF shows a 17% improvement in angular resolution and a 1.8 improvement in peak-to-background ratio with the RAPID2 system; the ESRF data vary more smoothly across detector channels. The time-dependent wide-angle XRD was tested by comparing a hydration reaction of gypsum-bassanite-anhydrite with energy-dispersive data collected on the same system on the same time scale. Three sample data sets from the reaction were selected for analysis and gave an average chi(2) of 3.8. The Rietveld-refined lattice parameters are a good match with published values and the corresponding errors show a mean value of 3.3 x 10(-4). The data have also been analysed by the Pawley decomposition phase-modelling technique demonstrating the ability of the station to quickly and accurately identify new phases. The combined SAXS/WAXS capability of the station was tested with the crystallization and spinodal decomposition of a very dilute polymer system. Our measurements show that the crystallization of a high-density co-polymer (E76B38) as low as 0.5% by weight can be observed in solution in hexane. The WAXS and SAXS data sets were collected on the same time scale. The SAXS detector was calibrated using a collagen sample that gave 30 orders of diffraction in 1 s of data collection. The combined XRD and XAS measurement capability of the station was tested by observing the collapse and re-crystallization of zinc-exchanged zeolite A (zeolite Zn/Na-A). Previous studies of this material on station 9.3 at the SRS were compared with those from the new station. A time improvement of 38 was observed with better quality counting statistics. The improved angular resolution from the WAXS detector enabled new peaks to be identified.
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Affiliation(s)
- R J Cernik
- Daresbury Laboratory, Warrington WA4 4AD, UK.
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Greaves GN, Meneau F, Sapelkin A, Colyer LM, ap Gwynn I, Wade S, Sankar G. The rheology of collapsing zeolites amorphized by temperature and pressure. Nat Mater 2003; 2:622-629. [PMID: 12942072 DOI: 10.1038/nmat963] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Accepted: 07/24/2003] [Indexed: 05/24/2023]
Abstract
Low-density zeolites collapse to the rigid amorphous state at temperatures that are well below the melting points of crystals of the same composition but of conventional density. Here we show, by using a range of experimental techniques, how the phenomenon of amorphization is time dependent, and how the dynamics of order-disorder transitions in zeolites under temperature and pressure are equivalent. As a result, thermobaric regions of instability can be charted, which are indicative of polyamorphism. Moreover, the boundaries of these zones depend on the rate at which temperature or pressure is ramped. By directly comparing the rheology of collapse with structural relaxation in equivalent melts, we conclude that zeolites amorphize like very strong liquids and, if compression occurs slowly, this is likely to lead to the synthesis of perfect glasses.
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Affiliation(s)
- G N Greaves
- Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ, UK.
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Meneau F, Cristol S, Sankar G, Dolbnya IP, Bras W, Catlow CRA, Thomas JM, Greaves GN. In situstudy of the formation of CdS nanoparticles by small-angle X-ray scattering. J Appl Crystallogr 2003. [DOI: 10.1107/s0021889803000219] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Meneau F, Sankar G, Morgante N, Winter R, Catlow CRA, Greaves GN, Thomas JM. Following the formation of nanometer-sized clusters by time-resolved SAXS and EXAFS techniques. Faraday Discuss 2003; 122:203-10; discussion 269-82. [PMID: 12555858 DOI: 10.1039/b203142f] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved in situ SAXS and XAS measurements were carried out to monitor the formation of nanoparticles of the sulfides of cadmium and zinc, from solutions containing he corresponding acetate, and thioacetamide under solvothermal conditions. Analysis of the SAXS data shows that particles of ca 5 nm in radius form within the first few minutes of the reaction and then grow uniformly to ca 20 nm over a period of two hours resulting in a highly mono-dispersed particle distribution. EXAFS data of the CdS particles also prepared by solvothermal methods and recorded at 20 K, support the formation of nano-meter sized particles.
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Affiliation(s)
- Florian Meneau
- Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London, UK W1S 4BS
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Greaves GN, Bras W, Oversluizen M, Clark SM. A SAXS/WAXS XAFS study of crystallisation in cordierite glass. Faraday Discuss 2003; 122:299-314; discussion 381-93. [PMID: 12555864 DOI: 10.1039/b202331h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New Cr X-ray absorption fine structure (XAFS) data have been combined with the results of small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) experiments to probe in detail the crystallisation mechanism in cordierite (Mg2Al4Si5O18) glass doped with 0.34 mol% Cr2O3. By direct comparison with chromo-aluminate spinels (MgCr2xAl2(1 - x)O4) Cr XAFS is used to determine the composition of the devitrified Cr species. This is identified as MgCr(0.18)Al(1.82)O4, which can be directly related to the Cr content in the starting glass and as a result the total crystalline volume in the fully developed ceramic is predicted to be 4%. In situ WAXS not only reveals the presence of the spinel phase but also a silica-rich stuffed quartz phase. This grows independently of the spinel and is probably nucleated from the glass surface. From our knowledge of the compositions of both crystalline phases we are able to deduce that the SAXS contrast between the surrounding glass and the spinel crystallites is 30 times greater than that between the quartz crystallites and the glass matrix, and therefore dominates the measured scattered intensity and the SAXS invariant that is derived from it. As a consequence we are able to show that the spinel crystalline volume fraction inherent in the SAXS is in close agreement with the 4% value obtained from the Cr XAFS. Furthermore in situ SAXS reveals the gradual development of the spinel particle size and shape during heat treatment. This is conducted in the super-cooled region just above the glass transition temperature, Tg. By employing a two-step annealing process nucleation can be separated from growth and from time-resolved SAXS measurements the alumino-chromate nanocrystals are found to be closely monodispersed. Over a total time course of 600 min they grow from rough crystallites to smooth spherical particles of radius 21 +/- 2 nm, with a final density of (1.2 +/- 0.4) x 10(21) m(-3). As the process of ceramic formation takes place in the viscous melt, growth is indeed found to be limited by diffusion and is complete when all the Cr is exhausted. We use this comprehensive in situ study of crystallisation in cordierite glass to demonstrate the advantages of combining SAXS, WAXS and XAFS for probing the time-resolved chemistry, the microstructure and its development from nucleation sites, that underpins the processing of nanoparticle ceramics.
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Affiliation(s)
- G N Greaves
- Department of Physics, University of Wales, Aberystwyth, UK SY23 3BZ
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Binsted N, Cook SL, Evans J, Greaves GN, Price RJ. EXAFS and near-edge structure in the cobalt K-edge absorption spectra of metal carbonyl complexes. J Am Chem Soc 2002. [DOI: 10.1021/ja00246a025] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sankar G, Wright PA, Natarajan S, Thomas JM, Greaves GN, Dent AJ, Dobson BR, Ramsdale CA, Jones RH. Combined QuEXAFS-XRD: a new technique in high-temperature materials chemistry; an illustrative in situ study of the zinc oxide-enhanced solid-state production of cordierite from a precursor zeolite. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100140a002] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Binsted N, Evans J, Greaves GN, Price RJ. Characterization of supported rhodium and ruthenium carbonyl clusters by EXAFS spectroscopy. Organometallics 2002. [DOI: 10.1021/om00105a007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Landron C, Hennet L, Jenkins TE, Greaves GN, Coutures JP, Soper AK. Liquid alumina: detailed atomic coordination determined from neutron diffraction data using empirical potential structure refinement. Phys Rev Lett 2001; 86:4839-4842. [PMID: 11384361 DOI: 10.1103/physrevlett.86.4839] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2000] [Indexed: 05/23/2023]
Abstract
The neutron scattering structure factor S(N)(Q) for a 40 mg drop of molten alumina (Al2O3) held at 2500 K, using a laser-heated aerodynamic levitation furnace, is measured for the first time. A 1700 atom model of liquid alumina is generated from these data using the technique of empirical potential structural refinement. About 62% of the aluminum sites are 4-fold coordinated, matching the mostly triply coordinated oxygen sites, but some 24% of the aluminum sites are 5-fold coordinated. The octahedral aluminum sites found in crystalline alpha-Al2O3 occur only at the 2% level in liquid alumina.
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Affiliation(s)
- C Landron
- Centre de Recherches sur les Matériaux à Haute Température, 45071, Orléans Cedex 2, France
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Cernik RJ, Clegg W, Catlow CR, Bushnell-Wye G, Flaherty JV, Greaves GN, Burrows I, Taylor DJ, Teat SJ, Hamichi M. A New High-Flux Chemical and Materials Crystallography Station at the SRS Daresbury. 1. Design, Construction and Test Results. J Synchrotron Radiat 1997; 4:279-286. [PMID: 16699241 DOI: 10.1107/s090904959901420x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/1999] [Accepted: 10/04/1999] [Indexed: 05/22/2023]
Abstract
A new single-crystal diffraction facility has been constructed on beamline 9 of the SRS at Daresbury Laboratory for the study of structural problems in chemistry and materials science. The station utilizes up to 3.8 mrad horizontally from the 5 T wiggler magnet which can be focused horizontally and vertically. The horizontal focusing is provided by a choice of gallium-cooled triangular bent Si (111) or Si (220) monochromators, giving a wavelength range from 0.3 to 1.5 A. Focusing in the vertical plane is achieved by a cylindrically bent zerodur mirror with a 300 mum-thick palladium coating. The station is equipped with a modified Enraf-Nonius CAD-4 four-circle diffractometer and a Siemens SMART CCD area-detector system. High- and low-temperature facilities are available to cover the temperature range from about 80 to 1000 K. Early results on test compounds without optimization of the beam optics demonstrate that excellent refined structures can be obtained from samples giving diffraction patterns too weak to be measured with conventional laboratory X-ray sources, fulfilling a major objective of the project.
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Cernik RJ, Clegg W, Catlow CR, Bushnell-Wye G, Flaherty JV, Greaves GN, Burrows I, Taylor DJ, Teat SJ, Hamichi M. A New High-Flux Chemical and Materials Crystallography Station at the SRS Daresbury. 1. Design, Construction and Test Results. J Synchrotron Radiat 1997; 4:279-86. [PMID: 16699241 DOI: 10.1107/s090904959701008x] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A new single-crystal diffraction facility has been constructed on beamline 9 of the SRS at Daresbury Laboratory for the study of structural problems in chemistry and materials science. The station utilizes up to 3.8 mrad horizontally from the 5 T wiggler magnet which can be focused horizontally and vertically. The horizontal focusing is provided by a choice of gallium-cooled triangular bent Si (111) or Si (220) monochromators, giving a wavelength range from 0.3 to 1.5 A. Focusing in the vertical plane is achieved by a cylindrically bent zerodur mirror with a 300 mum-thick palladium coating. The station is equipped with a modified Enraf-Nonius CAD-4 four-circle diffractometer and a Siemens SMART CCD area-detector system. High- and low-temperature facilities are available to cover the temperature range from about 80 to 1000 K. Early results on test compounds without optimization of the beam optics demonstrate that excellent refined structures can be obtained from samples giving diffraction patterns too weak to be measured with conventional laboratory X-ray sources, fulfilling a major objective of the project.
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38
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Smith W, Forester TR, Greaves GN, Hayter S, Gillan MJ. Molecular dynamics simulation of alkali-metal diffusion in alkali-metal disilicate glasses. ACTA ACUST UNITED AC 1997. [DOI: 10.1039/a606185k] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Shannon IJ, Rey F, Sankar G, Thomas JM, Maschmeyer T, Waller AM, Palomares AE, Corma A, Dent AJ, Greaves GN. Hydrotalcite-derived mixed oxides containing copper: catalysts for the removal of nitric oxide. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ft9969204331] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Epple M, Kirschnick H, Greaves GN, Sankar G, Thomas JM. Thermochemical reactivity of a solvate crystal studied by thermal analysis and in situ X-ray absorption spectroscopy. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ft9969205035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Corma A, Rey F, Thomas JM, Sankar G, Greaves GN, Cervilla A, Llopis E, Ribeira A. On the atomic environment and the mode of action of the catalytic centre in an intercalated oxo–molybdenum complex [MoO2{O2CC(S)Ph2}2]2–for oxygen-transfer reactions. Chem Commun (Camb) 1996. [DOI: 10.1039/cc9960001613] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ali F, Chadwick AV, Greaves GN, Jermy MC, Ngai KL, Smith ME. Examination of the mixed-alkali effect in (Li,Na) disilicate glasses by nuclear magnetic resonance and conductivity measurements. Solid State Nucl Magn Reson 1995; 5:133-143. [PMID: 8748651 DOI: 10.1016/0926-2040(95)00033-m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Results from 29Si, 23Na and 7Li magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, 7Li NMR relaxation and electrical conductivity in a series of [Li(1-x).Nax]2O.2SiO2 (disilicate) glasses are used to investigate the mixed-alkali effect. From the 29Si NMR spectra there is relatively little change of the network with alkali composition. 23Na and 7Li NMR linewidths and shifts change continuously as a function of composition, indicating that the alkali ions are intimately and uniformly mixed rather than separated into lithium and sodium-rich domains. The activation energy from electrical conductivity shows a distinct maximum at the central composition (x = 0.5), whereas the local activation energy for lithium motion determined from NMR shows only a smaller but monotonic increase as the lithium-content decreases.
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Affiliation(s)
- F Ali
- Chemical Laboratory, University of Kent, Canterbury, UK
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Greaves GN, Ngai KL. Reconciling ionic-transport properties with atomic structure in oxide glasses. Phys Rev B Condens Matter 1995; 52:6358-6380. [PMID: 9981865 DOI: 10.1103/physrevb.52.6358] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sankar G, Thomas JM, Rey F, Greaves GN. Probing the onset of crystallization of a microporous catalyst by combined X-ray absorption spectroscopy and X-ray diffraction. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/c39950002549] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clark SM, Christy AG, Jones R, Chen J, Thomas JM, Greaves GN. New high-pressure phase of GaAsO4: Implications for shape-memory materials. Phys Rev B Condens Matter 1995; 51:38-44. [PMID: 9977056 DOI: 10.1103/physrevb.51.38] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Thomas JM, Greaves GN, Sankar G, Wright PA, Chen J, Dent AJ, Marchese L. On the Nature of the Active Site in a CoAPO-18 Solid Acid Catalyst. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/anie.199418711] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Sankar G, Rey F, Thomas JM, Greaves GN, Corma A, Dobson BR, Dent AJ. Probing active sites in solid catalysts for the liquid-phase epoxidation of alkenes. ACTA ACUST UNITED AC 1994. [DOI: 10.1039/c39940002279] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Thomas JM, Greaves GN, Sankar G, Wright PA, Chen J, Dent AJ, Marchese L. Untersuchungen zur Struktur des aktiven Zentrums im sauren Feststoffkatalysator CoAPO-18. Angew Chem Int Ed Engl 1994. [DOI: 10.1002/ange.19941061810] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Greaves GN, Dent AJ, Dobson BR, Kalbitzer S, Pizzini S, Müller G. Environments of ion-implanted As and Ga impurities in amorphous silicon. Phys Rev B Condens Matter 1992; 45:6517-6533. [PMID: 10000413 DOI: 10.1103/physrevb.45.6517] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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