201
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Zhang H, Khalkhali M, Liu Q, Douglas JF. String-like cooperative motion in homogeneous melting. J Chem Phys 2013; 138:12A538. [PMID: 23556789 PMCID: PMC3598817 DOI: 10.1063/1.4769267] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 11/06/2012] [Indexed: 02/05/2023] Open
Abstract
Despite the fundamental nature and practical importance of melting, there is still no generally accepted theory of this ubiquitous phenomenon. Even the earliest simulations of melting of hard discs by Alder and Wainwright indicated the active role of collective atomic motion in melting and here we utilize molecular dynamics simulation to determine whether these correlated motions are similar to those found in recent studies of glass-forming (GF) liquids and other condensed, strongly interacting, particle systems. We indeed find string-like collective atomic motion in our simulations of "superheated" Ni crystals, but other observations indicate significant differences from GF liquids. For example, we observe neither stretched exponential structural relaxation, nor any decoupling phenomenon, while we do find a boson peak, findings that have strong implications for understanding the physical origin of these universal properties of GF liquids. Our simulations also provide a novel view of "homogeneous" melting in which a small concentration of interstitial defects exerts a powerful effect on the crystal stability through their initiation and propagation of collective atomic motion. These relatively rare point defects are found to propagate down the strings like solitons, driving the collective motion. Crystal integrity remains preserved when the permutational atomic motions take the form of ring-like atomic exchanges, but a topological transition occurs at higher temperatures where the rings open to form linear chains similar in geometrical form and length distribution to the strings of GF liquids. The local symmetry breaking effect of the open strings apparently destabilizes the local lattice structure and precipitates crystal melting. The crystal defects are thus not static entities under dynamic conditions, such as elevated temperatures or material loading, but rather are active agents exhibiting a rich nonlinear dynamics that is not addressed in conventional "static" defect melting models.
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Affiliation(s)
- Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4, Canada.
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202
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Gradenigo G, Trozzo R, Cavagna A, Grigera TS, Verrocchio P. Static correlations functions and domain walls in glass-forming liquids: The case of a sandwich geometry. J Chem Phys 2013; 138:12A509. [DOI: 10.1063/1.4771973] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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203
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Mickel W, Kapfer SC, Schröder-Turk GE, Mecke K. Shortcomings of the bond orientational order parameters for the analysis of disordered particulate matter. J Chem Phys 2013; 138:044501. [DOI: 10.1063/1.4774084] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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204
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Borba A, Gómez-Zavaglia A, Fausto R. Conformational Landscape, Photochemistry, and Infrared Spectra of Sulfanilamide. J Phys Chem A 2013; 117:704-17. [DOI: 10.1021/jp311789f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Ana Borba
- Department of Chemistry, University of Coimbra, P-3004-535, Portugal
| | - Andrea Gómez-Zavaglia
- Department of Chemistry, University of Coimbra, P-3004-535, Portugal
- Centro de Investigación
y Desarrollo en Criotecnología de Alimentos, Conicet La Plata, UNLP, RA-1900, Argentina
| | - Rui Fausto
- Department of Chemistry, University of Coimbra, P-3004-535, Portugal
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205
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Malins A, Eggers J, Tanaka H, Royall CP. Lifetimes and lengthscales of structural motifs in a model glassformer. Faraday Discuss 2013; 167:405-23. [DOI: 10.1039/c3fd00078h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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206
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Martinez-Garcia JC, Rzoska SJ, Drozd-Rzoska A, Martinez-Garcia J. A universal description of ultraslow glass dynamics. Nat Commun 2013; 4:1823. [PMID: 23652011 PMCID: PMC3674245 DOI: 10.1038/ncomms2797] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/21/2013] [Indexed: 11/08/2022] Open
Abstract
The dynamics of glass is of importance in materials science but its nature has not yet been fully understood. Here we report that a verification of the temperature dependencies of the primary relaxation time or viscosity in the ultraslowing/ultraviscous domain of glass-forming systems can be carried out via the analysis of the inverse of the Dyre-Olsen temperature index. The subsequent analysis of experimental data indicates the possibility of the self-consistent description of glass-forming low-molecular-weight liquids, polymers, liquid crystals, orientationally disordered crystals and Ising spin-glass-like systems, as well as the prevalence of equations associated with the 'finite temperature divergence'. All these lead to a new formula for the configurational entropy in glass-forming systems. Furthermore, a link to the dominated local symmetry for a given glass former is identified here. Results obtained show a new relationship between the glass transition and critical phenomena.
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207
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Tanaka H. Importance of many-body orientational correlations in the physical description of liquids. Faraday Discuss 2013; 167:9-76. [DOI: 10.1039/c3fd00110e] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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208
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Xie SJ, Qian HJ, Lu ZY. The influence of internal rotational barriers and temperature on static and dynamic properties of bulk atactic polystyrene. J Chem Phys 2012; 137:244903. [DOI: 10.1063/1.4772404] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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209
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Supercooled liquids with enhanced orientational order. Nat Commun 2012; 3:1233. [DOI: 10.1038/ncomms2228] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 10/26/2012] [Indexed: 11/08/2022] Open
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210
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Singh M, Agarwal M, Dhabal D, Chakravarty C. Structural correlations and cooperative dynamics in supercooled liquids. J Chem Phys 2012; 137:024508. [PMID: 22803548 DOI: 10.1063/1.4731705] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The relationships between diffusivity and the excess, pair and residual multiparticle contributions to the entropy are examined for Lennard-Jones liquids and binary glassformers, in the context of approximate inverse power law mappings of simple liquids. In the dense liquid where diffusivities are controlled by collisions and cage relaxations, Rosenfeld-type excess entropy scaling of diffusivities is found to hold for both crystallizing as well as vitrifying liquids. The crucial differences between the two categories of liquids emerge only when local cooperative effects in the dynamics result in significant caging effects in the time-dependent behaviour of the single-particle mean square displacement. In the case of glassformers, onset of such local cooperativity coincides with onset of deviations from Rosenfeld-type excess entropy scaling of diffusivities and increasing spatiotemporal heterogeneity. In contrast, for two- and three-dimensional liquids with a propensity to crystallise, the onset of local cooperative dynamics is sufficient to trigger crystallization provided that the liquid is sufficiently supercooled that the free energy barrier to nucleation of the solid phase is negligible. The state points corresponding to onset of transient caging effects can be associated with typical values, within reasonable bounds, of the excess, pair, and residual multiparticle entropy as a consequence of the isomorph-invariant character of the excess entropy, diffusivity and related static and dynamic correlation functions.
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Affiliation(s)
- Murari Singh
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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211
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Speck T, Malins A, Royall CP. First-order phase transition in a model glass former: coupling of local structure and dynamics. PHYSICAL REVIEW LETTERS 2012; 109:195703. [PMID: 23215402 DOI: 10.1103/physrevlett.109.195703] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Indexed: 05/13/2023]
Abstract
Recently, numerical evidence for a dynamical first-order phase transition in trajectory space [L.O. Hedges et al., Science 323, 1309 (2009)] has been found. In a model glass former in which clusters of 11 particles form upon cooling, we find that the transition has both dynamical and structural character. It occurs between an active phase with a high fraction of mobile and low fraction of cluster particles, and an inactive phase with few mobile but many cluster particles. The transition can be driven both dynamically and structurally with a chemical potential, showing that local order forms a mechanism for dynamical arrest.
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Affiliation(s)
- Thomas Speck
- Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
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212
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Dunleavy AJ, Wiesner K, Royall CP. Using mutual information to measure order in model glass formers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:041505. [PMID: 23214589 DOI: 10.1103/physreve.86.041505] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 08/23/2012] [Indexed: 06/01/2023]
Abstract
Whether or not there is growing static order accompanying the dynamical heterogeneity and increasing relaxation times seen in glassy systems is a matter of dispute. An obstacle to resolving this issue is that the order is expected to be amorphous and so not amenable to simple order parameters. We use mutual information to provide a general measurement of order that is sensitive to multiparticle correlations. We apply this to two glass-forming systems (two-dimensional binary mixtures of hard disks with different size ratios to give varying amounts of hexatic order) and show that there is little growth of amorphous order in the system without crystalline order. In both cases we measure the dynamical length with a four-point correlation function and find that it increases significantly faster than the static lengths in the system as density is increased. We further show that we can recover the known scaling of the dynamic correlation length in a kinetically constrained model, the two-vacancy-assisted-hopping triangular lattice gas.
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Affiliation(s)
- Andrew J Dunleavy
- Centre for Complexity Sciences, School of Chemistry, University of Bristol, Bristol BS8 1TW, United Kingdom.
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213
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Tanaka H. Bond orientational order in liquids: Towards a unified description of water-like anomalies, liquid-liquid transition, glass transition, and crystallization: Bond orientational order in liquids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:113. [PMID: 23104614 DOI: 10.1140/epje/i2012-12113-y] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 09/28/2012] [Indexed: 06/01/2023]
Abstract
There are at least three fundamental states of matter, depending upon temperature and pressure: gas, liquid, and solid (crystal). These states are separated by first-order phase transitions between them. In both gas and liquid phases a complete translational and rotational symmetry exist, whereas in a solid phase both symmetries are broken. In intermediate phases between liquid and solid, which include liquid crystal and plastic crystal phases, only one of the two symmetries is preserved. Among the fundamental states of matter, the liquid state is the most poorly understood. We argue that it is crucial for a better understanding of liquids to recognize that a liquid generally has the tendency to have a local structural order and its presence is intrinsic and universal to any liquid. Such structural ordering is a consequence of many-body correlations, more specifically, bond angle correlations, which we believe are crucial for the description of the liquid state. We show that this physical picture may naturally explain difficult unsolved problems associated with the liquid state, such as anomalies of water-type liquids (water, Si, Ge, ...), liquid-liquid transition, liquid-glass transition, crystallization and quasicrystal formation, in a unified manner. In other words, we need a new order parameter representing a low local free-energy configuration, which is a bond orientational order parameter in many cases, in addition to a density order parameter for the physical description of these phenomena. Here we review our two-order-parameter model of liquid and consider how transient local structural ordering is linked to all of the above-mentioned phenomena. The relationship between these phenomena is also discussed.
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Affiliation(s)
- Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505, Tokyo, Japan.
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214
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Syutkin VM, Vyazovkin VL, Korolev VV, Grebenkin SY. Length and time scales of structural heterogeneities in deeply supercooled propylene carbonate. PHYSICAL REVIEW LETTERS 2012; 109:137801. [PMID: 23030120 DOI: 10.1103/physrevlett.109.137801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Indexed: 06/01/2023]
Abstract
Deactivation of excited phenanthrene by molecular oxygen is utilized to probe the structural heterogeneity of supercooled propylene carbonate. The diffusion rate of oxygen molecules in different regions varies over two orders of magnitude. The size of the regions of different oxygen mobility was determined to be 1.5 nm. Values from 0.2 to 30 s have been obtained for the lifetime of these regions over a temperature range from T(g)-1 to T(g)+4 K (T(g)=158 K). The heterogeneity lifetime is in close agreement with the α-relaxation time determined by dielectric spectroscopy. The obtained results argue in favor of the statement that the heterogeneous cooperative dynamics of host molecules (so-called dynamical heterogeneity) is of structural origin.
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Affiliation(s)
- V M Syutkin
- Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russian Federation.
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215
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Patashinski AZ, Ratner MA, Grzybowski BA, Orlik R, Mitus AC. Heterogeneous Structure, Heterogeneous Dynamics, and Complex Behavior in Two-Dimensional Liquids. J Phys Chem Lett 2012; 3:2431-2435. [PMID: 26292128 DOI: 10.1021/jz301006j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Analysis of the metrical and topological features of the local structure in a freezing two-dimensional Lennard-Jones system found that in a narrow strip [Formula: see text] of thermodynamic states close to the melting line, the liquid becomes a complex liquid characterized by a super-Arrhenius increase of relaxation times, stretched-exponential decay of correlations in time, and a power-law distribution of waiting times for changes in the local order. In [Formula: see text], the structure of the liquid and its dynamics are spatially heterogeneous; the sizes of ordered clusters are power-law distributed. Those features are governed by local structure evolution between solid-like and liquid-like (disordered) patterns. The liquid inside the strip [Formula: see text] gives a unique opportunity to study how heterogeneous structure, dynamics and complexity are intertwined with each other on a microscopic level.
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Affiliation(s)
- A Z Patashinski
- †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - M A Ratner
- †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - B A Grzybowski
- †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - R Orlik
- ‡Orlik Software, ul. Lniana 22/12, 50-520 Wroclaw, Poland
| | - A C Mitus
- §Insitute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
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216
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Martinez-Garcia JC, Martinez-Garcia J, Rzoska SJ, Hulliger J. The new insight into dynamic crossover in glass forming liquids from the apparent enthalpy analysis. J Chem Phys 2012; 137:064501. [DOI: 10.1063/1.4739750] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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217
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Leocmach M, Tanaka H. Roles of icosahedral and crystal-like order in the hard spheres glass transition. Nat Commun 2012; 3:974. [DOI: 10.1038/ncomms1974] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 06/25/2012] [Indexed: 11/09/2022] Open
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218
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Mosayebi M, Del Gado E, Ilg P, Öttinger HC. Deformation of inherent structures to detect long-range correlations in supercooled liquids. J Chem Phys 2012; 137:024504. [DOI: 10.1063/1.4732859] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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219
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Russo J, Tanaka H. The microscopic pathway to crystallization in supercooled liquids. Sci Rep 2012; 2:505. [PMID: 22792437 PMCID: PMC3395031 DOI: 10.1038/srep00505] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/27/2012] [Indexed: 11/29/2022] Open
Abstract
Despite its fundamental and technological importance, a microscopic understanding of the crystallization process is still elusive. By computer simulations of the hard-sphere model we reveal the mechanism by which thermal fluctuations drive the transition from the supercooled liquid state to the crystal state. In particular we show that fluctuations in bond orientational order trigger the nucleation process, contrary to the common belief that the transition is initiated by density fluctuations. Moreover, the analysis of bond orientational fluctuations shows that these not only act as seeds of the nucleation process, but also i) determine the particular polymorph which is to be nucleated from them and ii) at high density favour the formation of fivefold structures which can frustrate the formation of crystals. These results can shed new light on our understanding of the relationship between crystallization and vitrification.
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Affiliation(s)
- John Russo
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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220
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Davatolhagh S, Foroozan S. Structural origin of enhanced translational diffusion in two-dimensional hard-ellipse fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061707. [PMID: 23005114 DOI: 10.1103/physreve.85.061707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Indexed: 06/01/2023]
Abstract
The static correlations and diffusive dynamics of hard ellipses are investigated in the isotropic and nematic phases by Monte Carlo simulation. In particular, an enhancement of the translational diffusion with respect to the rotational diffusion is observed at an onset concentration φ_{on} within the isotropic phase, which is explained in terms of the formation of unstable nematic-like regions with a mean lifetime that exceeds the characteristic time of diffusion at φ_{on}. The relevance to the onset of spatially heterogeneous dynamics in supercooled glass-forming liquids is discussed.
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Affiliation(s)
- S Davatolhagh
- Department of Physics, College of Sciences, Shiraz University, Shiraz 71454, Iran
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221
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Cavagna A, Grigera TS, Verrocchio P. Dynamic relaxation of a liquid cavity under amorphous boundary conditions. J Chem Phys 2012; 136:204502. [DOI: 10.1063/1.4720477] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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222
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Hwang J, Melgarejo ZH, Kalay YE, Kalay I, Kramer MJ, Stone DS, Voyles PM. Nanoscale structure and structural relaxation in Zr50Cu45Al5 bulk metallic glass. PHYSICAL REVIEW LETTERS 2012; 108:195505. [PMID: 23003058 DOI: 10.1103/physrevlett.108.195505] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Indexed: 06/01/2023]
Abstract
Hybrid reverse Monte Carlo simulations of the structure of Zr50Cu45Al5 bulk metallic glass incorporating medium-range structure from fluctuation electron microscopy data and short-range structure from an embedded atom potential produce structures with significant fractions of icosahedral- and crystal-like atomic clusters. Similar clusters group together into nanometer-scale regions, and relaxation transforms crystal-like clusters into icosahedral clusters. A model refined against only the potential does not agree with the fluctuation microscopy data and contains few crystal-like clusters.
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Affiliation(s)
- Jinwoo Hwang
- Department of Materials Science and Engineering, University of Wisconsin, Madison, Madison, Wisconsin 53706, USA
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223
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Ronceray P, Harrowell P. Geometry and the entropic cost of locally favoured structures in a liquid. J Chem Phys 2012; 136:134504. [DOI: 10.1063/1.3701617] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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224
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Ronhovde P, Chakrabarty S, Hu D, Sahu M, Sahu KK, Kelton KF, Mauro NA, Nussinov Z. Detection of hidden structures for arbitrary scales in complex physical systems. Sci Rep 2012; 2:329. [PMID: 22461970 PMCID: PMC3314987 DOI: 10.1038/srep00329] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 02/29/2012] [Indexed: 11/14/2022] Open
Abstract
Recent decades have experienced the discovery of numerous complex materials. At the root of the complexity underlying many of these materials lies a large number of contending atomic- and largerscale configurations. In order to obtain a more detailed understanding of such systems, we need tools that enable the detection of pertinent structures on all spatial and temporal scales. Towards this end, we suggest a new method that applies to both static and dynamic systems which invokes ideas from network analysis and information theory. Our approach efficiently identifies basic unit cells, topological defects, and candidate natural structures. The method is particularly useful where a clear definition of order is lacking, and the identified features may constitute a natural point of departure for further analysis.
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225
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Lad KN, Jakse N, Pasturel A. Signatures of fragile-to-strong transition in a binary metallic glass-forming liquid. J Chem Phys 2012; 136:104509. [DOI: 10.1063/1.3692610] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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226
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227
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Schwahn D, Pipich V, Richter D. Composition and Long-Range Density Fluctuations in PEO/PMMA Polymer Blends: A Result of Asymmetric Component Mobility. Macromolecules 2012. [DOI: 10.1021/ma2019123] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dietmar Schwahn
- Jülich Centre for Neutron
Science JCNS and Institute for Complex Systems ICS, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Vitaliy Pipich
- Jülich Centre for Neutron
Science JCNS-FRM II, Forschungszentrum Jülich GmbH, Outstation at FRM II, Lichtenbergstraße 1,
D-85747 Garching, Germany
| | - Dieter Richter
- Jülich Centre for Neutron
Science JCNS and Institute for Complex Systems ICS, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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228
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Charbonneau B, Charbonneau P, Tarjus G. Geometrical frustration and static correlations in a simple glass former. PHYSICAL REVIEW LETTERS 2012; 108:035701. [PMID: 22400759 DOI: 10.1103/physrevlett.108.035701] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Indexed: 05/31/2023]
Abstract
We study the geometrical frustration scenario of glass formation for simple hard-sphere models. We find that the dual picture in terms of defects brings little insight and no theoretical simplification for the understanding of the slowing down of relaxation, because of the strong frustration characterizing these systems. The possibility of a growing static length is furthermore found to be physically irrelevant in the regime that is accessible to computer simulations.
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Affiliation(s)
- Benoit Charbonneau
- Mathematics Department, St. Jerome's University in the University of Waterloo, Waterloo, Ontario, Canada
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229
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Berthier L, Kob W. Static point-to-set correlations in glass-forming liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:011102. [PMID: 22400507 DOI: 10.1103/physreve.85.011102] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Indexed: 05/31/2023]
Abstract
We analyze static point-to-set correlations in glass-forming liquids. The generic idea is to freeze the position of a set of particles in an equilibrium configuration and to perform sampling in the presence of this additional constraint. Qualitatively different geometries for the confining set of particles are considered and a detailed comparison of resulting static and dynamic correlation functions is performed. Our results reveal the existence of static spatial correlations not detected by conventional two-body correlators, which appear to be decoupled from, and shorter-ranged than, dynamical length scales characterizing dynamic heterogeneity. We find that the dynamics slows down dramatically under confinement, which suggests new ways to investigate the glass transition. Our results indicate that the geometry in which particles are randomly pinned is the best candidate to study static correlations.
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Affiliation(s)
- Ludovic Berthier
- Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, 34095 Montpellier, France
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230
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231
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Popova VA, Surovtsev NV. Temperature dependence of the Landau-Placzek ratio in glass forming liquids. J Chem Phys 2011; 135:134510. [DOI: 10.1063/1.3645196] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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232
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Kobayashi M, Tanaka H. Relationship between the phase diagram, the glass-forming ability, and the fragility of a water/salt mixture. J Phys Chem B 2011; 115:14077-90. [PMID: 21916518 DOI: 10.1021/jp203855c] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Water is known to be an exceptionally poor glass former, which is a significant drawback in the low-temperature storage of food and biomatter. This is one of the characteristic features of water, but its link to the thermodynamic and kinetic anomalies of water remains elusive. Recently, we showed that the glass-forming ability and the fragility of a water/salt mixture are closely related to its equilibrium phase diagram [Kobayashi, M.; Tanaka, H. Phys. Rev. Lett.2011, 106, 125703]. Here we propose that frustration between local and global orderings controls both the glass-forming ability and fragility on the basis of experimental evidence. Relying on the same role of salt and pressure, which commonly breaks tetrahedral order, we apply this idea to pure water under pressure. This scenario not only explains unusual behavior of water-type liquids such as water, Si, and Ge but also provides a general explanation on the link between the equilibrium phase diagram, the glass-forming ability, and the fragility of various materials including oxides, chalcogenides, and metallic glasses.
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Affiliation(s)
- Mika Kobayashi
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Tokyo 153-8505, Japan
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233
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Mazoyer S, Ebert F, Maret G, Keim P. Correlation between dynamical heterogeneities, structure and potential-energy distribution in a 2D amorphous solid. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:101. [PMID: 21947899 DOI: 10.1140/epje/i2011-11101-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 07/19/2011] [Accepted: 08/15/2011] [Indexed: 05/31/2023]
Abstract
We investigate the collective properties of particles in a 2D experimental system which consists of a bi-disperse mixture of colloidal particles confined at an air/water interface. We find a direct correlation between structure and dynamical heterogeneities in this system: particles belonging to locally ordered structures have lower potential energy and are slower than other particles. In a more general way we show that particles with high potential energy are dominating the dynamics especially in the α-relaxation regime.
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Affiliation(s)
- S Mazoyer
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
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234
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Rodney D, Schrøder T. On the potential energy landscape of supercooled liquids and glasses. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:100. [PMID: 21947901 DOI: 10.1140/epje/i2011-11100-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 07/11/2011] [Accepted: 08/04/2011] [Indexed: 05/31/2023]
Abstract
The activation-relaxation technique (ART), a saddle-point search method, is applied to determine the potential energy landscape around supercooled and glassy configurations of a three-dimensional binary Lennard-Jones system. We show a strong relation between the distribution of activation energies around a given glassy configuration and its history, in particular, the cooling rate used to produce the glass and whether or not the glass was plastically deformed prior to sampling. We also compare the thermally activated transitions found by ART around a supercooled configuration with the succession of transitions undergone by the same supercooled liquid during a time trajectory simulated by molecular dynamics. We find that ART is biased towards more heterogeneous transitions with higher activation energies and more broken bonds than the MD simulation.
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Affiliation(s)
- D Rodney
- Laboratoire Science et Ingénierie des Matériaux et Procédés, Grenoble INP, UJF, CNRS, Domaine Universitaire BP 46, F38402 Saint Martin d'Hères, France.
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235
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Ronhovde P, Chakrabarty S, Hu D, Sahu M, Sahu KK, Kelton KF, Mauro NA, Nussinov Z. Detecting hidden spatial and spatio-temporal structures in glasses and complex physical systems by multiresolution network clustering. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:105. [PMID: 21959545 DOI: 10.1140/epje/i2011-11105-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 08/03/2011] [Accepted: 08/05/2011] [Indexed: 05/31/2023]
Abstract
We elaborate on a general method that we recently introduced for characterizing the "natural" structures in complex physical systems via multi-scale network analysis. The method is based on "community detection" wherein interacting particles are partitioned into an "ideal gas" of optimally decoupled groups of particles. Specifically, we construct a set of network representations ("replicas") of the physical system based on interatomic potentials and apply a multiscale clustering ("multiresolution community detection") analysis using information-based correlations among the replicas. Replicas may i) be different representations of an identical static system, ii) embody dynamics by considering replicas to be time separated snapshots of the system (with a tunable time separation), or iii) encode general correlations when different replicas correspond to different representations of the entire history of the system as it evolves in space-time. Inputs for our method are the inter-particle potentials or experimentally measured two (or higher order) particle correlations. We apply our method to computer simulations of a binary Kob-Andersen Lennard-Jones system in a mixture ratio of A(80)B(20) , a ternary model system with components "A", "B", and "C" in ratios of A(88)B(7)C(5) (as in Al(88)Y(7)Fe(5) , and to atomic coordinates in a Zr(80)Pt(20) system as gleaned by reverse Monte Carlo analysis of experimentally determined structure factors. We identify the dominant structures (disjoint or overlapping) and general length scales by analyzing extrema of the information theory measures. We speculate on possible links between i) physical transitions or crossovers and ii) changes in structures found by this method as well as phase transitions associated with the computational complexity of the community detection problem. We also briefly consider continuum approaches and discuss rigidity and the shear penetration depth in amorphous systems; this latter length scale increases as the system becomes progressively rigid.
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Affiliation(s)
- P Ronhovde
- Department of Physics, Washington University in St. Louis, Campus Box 1105, 1 Brookings Drive, St. Louis, MO 63130, USA
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236
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Tanaka H. Roles of bond orientational ordering in glass transition and crystallization. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:284115. [PMID: 21709320 DOI: 10.1088/0953-8984/23/28/284115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
It is widely believed that crystallization in three dimensions is primarily controlled by positional ordering, and not by bond orientational ordering. In other words, bond orientational ordering is usually considered to be merely a consequence of positional ordering and thus has often been ignored. This one-order-parameter (density) description may be reasonable when we consider an equilibrium liquid-solid transition, but may not be enough to describe a metastable state and the kinetics of the transition. Here we propose that bond orientational ordering can play a key role in (i) crystallization, (ii) the ordering to quasi-crystal and (iii) vitrification, which occurs under rather weak frustration against crystallization. In a metastable supercooled state before crystallization, a system generally tends to have bond orientational order at least locally as a result of a constraint of dense packing. For a system interacting with hard-core repulsions, the constraint is intrinsically of geometrical origin and thus the basic physics is the same as nematic ordering of rod-like particles upon densification. Furthermore, positional ordering is easily destroyed even by weak frustration such as polydispersity and anisotropic interactions which favour a symmetry not consistent with that of the equilibrium crystal. Thus we may say that vitrification can be achieved by disturbing and prohibiting long-range positional ordering. Even in such a situation, bond orientational ordering still survives, accompanying its critical-like fluctuations, which are the origin of dynamic heterogeneity for this case. This scenario naturally explains both the absence of positional order and the development of bond orientational order upon cooling in a supercooled state. Although our argument is speculative in nature, we emphasize that this physical picture can coherently explain crystallization, vitrification, quasi-crystallization and their relationship in a natural manner. For a strongly frustrated system, even bond orientational order can be destroyed. Even in such a case there may still appear a structural signature of dense packing, which is linked to slow dynamics.
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Affiliation(s)
- Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, Tokyo, Japan.
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237
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Razul MSG, Matharoo GS, Poole PH. Spatial correlation of the dynamic propensity of a glass-forming liquid. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:235103. [PMID: 21613718 DOI: 10.1088/0953-8984/23/23/235103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present computer simulation results on the dynamic propensity (as defined by Widmer-Cooper et al 2004 Phys. Rev. Lett. 93 135701) in a Kob-Andersen binary Lennard-Jones liquid system consisting of 8788 particles. We compute the spatial correlation function for the dynamic propensity as a function of both the reduced temperature T, and the time scale on which the particle displacements are measured. For T ≤ 0.6, we find that non-zero correlations occur at the largest length scale accessible in our system. We also show that a cluster-size analysis of particles with extremal values of the dynamic propensity, as well as 3D visualizations, reveal spatially correlated regions that approach the size of our system as T decreases, consistently with the behavior of the spatial correlation function. Next, we define and examine the 'coordination propensity', the isoconfigurational average of the coordination number of the minority B particles around the majority A particles. We show that a significant correlation exists between the spatial fluctuations of the dynamic and coordination propensities. In addition, we find non-zero correlations of the coordination propensity occurring at the largest length scale accessible in our system for all T in the range 0.466 < T < 1.0. We discuss the implications of these results for understanding the length scales of dynamical heterogeneity in glass-forming liquids.
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Affiliation(s)
- M Shajahan G Razul
- Department of Physics, St Francis Xavier University, Antigonish, NS, B2G 2W5, Canada
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238
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Watanabe K, Kawasaki T, Tanaka H. Structural origin of enhanced slow dynamics near a wall in glass-forming systems. NATURE MATERIALS 2011; 10:512-520. [PMID: 21623378 DOI: 10.1038/nmat3034] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 04/26/2011] [Indexed: 05/30/2023]
Abstract
Spatial confinement is known to induce a drastic change in the viscosity, relaxation times, and flow profile of liquids near the glass (or jamming) transition point. The essential underlying question is how a wall affects the dynamics of densely packed systems. Here we study this fundamental problem, using experiments on a driven granular hard-sphere liquid and numerical simulations of polydisperse and bidisperse colloidal liquids. The nearly hard-core nature of the particle-wall interaction provides an ideal opportunity to study purely geometrical confinement effects. We reveal that the slower dynamics near a wall is induced by wall-induced enhancement of 'glassy structural order', which is a manifestation of strong interparticle correlations. By generalizing the structure-dynamics relation for bulk systems, we find a quantitative relation between the structural relaxation time at a certain distance from a wall and the correlation length of glassy structural order there. Our finding suggests that glassy structural ordering may be the origin of the slow glassy dynamics of a supercooled liquid.
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Affiliation(s)
- Keiji Watanabe
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Tokyo 153-8505, Japan
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239
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Kawasaki T, Tanaka H. Structural signature of slow dynamics and dynamic heterogeneity in two-dimensional colloidal liquids: glassy structural order. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:194121. [PMID: 21525551 DOI: 10.1088/0953-8984/23/19/194121] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Glassy states are formed if crystallization is avoided upon cooling or increasing density. However, the physical factors controlling the ease of vitrification and the nature of glass transition remain elusive. Among various glass-forming systems, colloidal liquids are one of the most ideal glass-forming systems because of the simplicity and controllability of the interactions. We use numerical simulations of two-dimensional polydisperse and binary hard discs to tackle both of these longstanding questions. For polydisperse systems, we systematically control the polydispersity, which can be regarded as the strength of frustration effects on crystallization. We reveal that crystal-like hexatic order grows in size and lifetime with an increase in the colloid volume fraction or with a decrease in polydispersity (or frustration). We stress that hexatic ordering in hard disc systems is a direct consequence of dense packing and a manifestation of low configurational entropy. Our study suggests an intriguing scenario that the strength of frustration controls both the ease of vitrification and the nature of the glass transition. Vitrification may be a process of hidden crystal-like ordering under frustration for this system. This may provide not only a physical basis for glass formation, but also an answer to another longstanding question on the structure of amorphous materials: 'order in disorder' may be an intrinsic feature of a glassy state of many materials. For binary mixtures, on the other hand, the relevant structural feature linked to slow dynamics is not hexatic order, but an amorphous structure of low structural entropy. These results suggest that slow dynamics is associated with bond orientational order linked to the crystal for a weakly frustrated system, whereas to amorphous structures of low configurational entropy for a strongly frustrated system. This suggests an intrinsic link between structure and dynamics in glass-forming materials: slow dynamics is linked to structuring ('glassy ordering') towards low configurational entropy. We discuss the nature of 'glassy order' responsible for slow dynamics.
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Affiliation(s)
- Takeshi Kawasaki
- Institute of Industrial Science, University of Tokyo, Tokyo, Japan
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240
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Tournier F R. Thermodynamic Origin of the Vitreous Transition. MATERIALS (BASEL, SWITZERLAND) 2011; 4:869-892. [PMID: 28879955 PMCID: PMC5448590 DOI: 10.3390/ma4050869] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 04/19/2011] [Accepted: 05/05/2011] [Indexed: 11/16/2022]
Abstract
The vitreous transition is characterized by a freezing of atomic degrees of freedom at a temperature Tg depending on the heating and cooling rates. A kinetic origin is generally attributed to this phenomenon instead of a thermodynamic one which we develop here. Completed homogeneous nucleation laws reflecting the energy saving due to Fermi energy equalization of nascent crystals and their melt are used. They are applied to bulk metallic glasses and extended to inorganic glasses and polymers. A transition T*g among various Tg corresponds to a crystal homogeneous nucleation temperature, leading to a preliminary formation of a cluster distribution during the relaxation time preceding the long steady-state nucleation time of crystals in small samples. The thermally-activated energy barrier ΔG*2ls/kBT at T*g for homogeneous nucleation is nearly the same in all glass-forming melts and determined by similar values of viscosity and a thermally-activated diffusion barrier from melt to cluster. The glass transition T*g is a material constant and a linear function of the energy saving associated with charge transfers from nascent clusters to the melt. The vitreous transition and the melting temperatures alone are used to predict the free-volume disappearance temperature equal to the Vogel-Fulcher-Tammann temperature of fragile glass-forming melts, in agreement with many viscosity measurements. The reversible thermodynamic vitreous transition is determined by the disappearance temperature T*g of the fully-relaxed enthalpy Hr that is not time dependent; the observed specific heat jump at T*g is equal to the proportionality coefficient of Hr with (T*g - Ta) for T ≤ T*g as expected from the enthalpy excess stored by a quenched undercooled melt at the annealing temperature Ta and relaxed towards an equilibrium vitreous state. However, the heat flux measurements found in literature over the last 50 years only gave an out-of-equilibrium Tg since the enthalpy is continuous at T*g without visible heat jump.
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Affiliation(s)
- Robert Tournier F
- Centre National de la Recherche Scientifique, Université Joseph Fourier, Consortium de Recherches pour l'Emergence de Technologies Avancées, B.P. 166, 38042 Grenoble Cedex 09, France.
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241
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Coslovich D. Locally preferred structures and many-body static correlations in viscous liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:051505. [PMID: 21728538 DOI: 10.1103/physreve.83.051505] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 05/31/2023]
Abstract
The influence of static correlations beyond the pair level on the dynamics of selected model glass formers is investigated. The pair structure, angular distribution functions, and statistics of Voronoi polyhedra of two well-known Lennard-Jones mixtures as well as of the corresponding Weeks-Chandler-Andersen variants, in which the attractive part of the potential is truncated, are compared. By means of the Voronoi construction, the atomic arrangements corresponding to the locally preferred structures of the models are identified. It is found that the growth of domains formed by interconnected locally preferred structures signals the onset of the slow-dynamics regime and allows the rationalization of the different dynamic behaviors of the models. At low temperature, the spatial extension of the structurally correlated domains, evaluated at fixed relaxation time, increases with the fragility of the models and is systematically reduced by truncating the attractions. In view of these results, proper inclusion of many-body static correlations in theories of the glass transition appears crucial for the description of the dynamics of fragile glass formers.
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Affiliation(s)
- Daniele Coslovich
- Laboratoire Charles Coulomb UMR 5221, Université Montpellier 2 and CNRS, Montpellier, France.
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242
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Berry J, Grant M. Modeling multiple time scales during glass formation with phase-field crystals. PHYSICAL REVIEW LETTERS 2011; 106:175702. [PMID: 21635050 DOI: 10.1103/physrevlett.106.175702] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 04/01/2011] [Indexed: 05/30/2023]
Abstract
The dynamics of glass formation in monatomic and binary liquids are studied numerically using a microscopic field theory for the evolution of the time-averaged atomic number density. A stochastic framework combining phase-field crystal free energies and dynamic density functional theory is shown to successfully describe several aspects of glass formation over multiple time scales. Agreement with mode coupling theory is demonstrated for underdamped liquids at moderate supercoolings, and a rapidly growing dynamic correlation length is found to be associated with fragile behavior.
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Affiliation(s)
- Joel Berry
- Physics Department, McGill University, 3600 rue University, Montréal, Québec, Canada H3A 2T8
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243
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Wang Z, Yu HB, Wen P, Bai HY, Wang WH. Pronounced slow β-relaxation in La-based bulk metallic glasses. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:142202. [PMID: 21422505 DOI: 10.1088/0953-8984/23/14/142202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Most metallic glasses (MGs) exhibit weak evidence of slow β-relaxation in their dynamic mechanical spectroscopy spectra. In contrast to other MGs, the La-based MGs we report here show a distinct slow β-relaxation peak in the mechanical relaxation measurements. We find that the slow β-relaxation behavior can be tuned by modification of the chemical composition and fragility. The structural origin of the slow β-relaxation and correlation between β-relaxation and α-relaxation in the MGs are also discussed. MGs with pronounced slow β-relaxation and tunable properties might provide a model system to investigate some long-standing issues in the glass field.
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Affiliation(s)
- Z Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
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244
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Liu YH, Wang D, Nakajima K, Zhang W, Hirata A, Nishi T, Inoue A, Chen MW. Characterization of nanoscale mechanical heterogeneity in a metallic glass by dynamic force microscopy. PHYSICAL REVIEW LETTERS 2011; 106:125504. [PMID: 21517325 DOI: 10.1103/physrevlett.106.125504] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/24/2011] [Indexed: 05/10/2023]
Abstract
We report nanoscale mechanical heterogeneity of a metallic glass characterized by dynamic force microscopy. Apparent energy dissipation with a variation of ~12%, originating from nonuniform distribution of local viscoelasticity, was observed. The correlation length of the heterogeneity was measured to be ~2.5 nm, consistent with the dimension of shear transformation zones for plastic flow. This study provides the first experimental evidence on the nanoscale viscoelastic heterogeneity in metallic glasses and may fill the gap between atomic models and macroscopic glass properties.
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Affiliation(s)
- Y H Liu
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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245
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246
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Hwang J, Voyles PM. Variable resolution fluctuation electron microscopy on Cu-Zr metallic glass using a wide range of coherent STEM probe size. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2011; 17:67-74. [PMID: 21122191 DOI: 10.1017/s1431927610094109] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report variable resolution fluctuation electron microscopy (VRFEM) measurements on Cu64.5Zr35.5 metallic glass acquired using scanning transmission electron microscopy nanodiffraction using coherent probes 0.8 to 11 nm in diameter. The VRFEM results show that medium range atomic order structure of Cu64.5Zr35.5 bulk metallic glass at the ∼ 1 nm scale has large fluctuations, but the structure becomes almost completely homogeneous at the 11 nm scale. We show that our experimental VRFEM data are consistent with two different models, the pair persistent model and the amorphous/nanocrystal composite model. We also report a new way to filter VRFEM data to eliminate the effect of specimen thickness gradient using high-angle annular dark field images as references.
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Affiliation(s)
- Jinwoo Hwang
- Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706-1595, USA.
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247
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Yunker PJ, Chen K, Zhang Z, Ellenbroek WG, Liu AJ, Yodh AG. Rotational and translational phonon modes in glasses composed of ellipsoidal particles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:011403. [PMID: 21405694 DOI: 10.1103/physreve.83.011403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 12/01/2010] [Indexed: 05/30/2023]
Abstract
The effects of particle shape on the vibrational properties of colloidal glasses are studied experimentally. "Ellipsoidal glasses" are created by stretching polystyrene spheres to different aspect ratios and then suspending the resulting ellipsoidal particles in water at a high packing fraction. By measuring displacement correlations between particles, we extract vibrational properties of the corresponding "shadow" ellipsoidal glass with the same geometric configuration and interactions as the "source" suspension but without damping. Low-frequency modes in glasses composed of ellipsoidal particles with major-to-minor axis aspect ratios of ~1.1 are observed to have predominantly rotational character. In contrast, low-frequency modes in glasses of ellipsoidal particles with larger aspect ratios (~3.0) exhibit a mixed rotational and translational character. All glass samples were characterized by a distribution of particles with different aspect ratios. Interestingly, even within the same sample it was found that small-aspect-ratio particles participate relatively more in rotational modes, while large-aspect-ratio particles tend to participate relatively more in translational modes.
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Affiliation(s)
- Peter J Yunker
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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248
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Affiliation(s)
- C. M. Roland
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington, D.C. 20375-5342
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249
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Drozd-Rzoska A, Rzoska SJ, Pawlus S, Martinez-Garcia JC, Tamarit JL. Evidence for critical-like behavior in ultraslowing glass-forming systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:031501. [PMID: 21230077 DOI: 10.1103/physreve.82.031501] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Indexed: 05/30/2023]
Abstract
Glass transition constitutes one of main problems of condensed matter physics and material engineering that remains unsolved. The common acceptance of the Vogel-Fulcher-Tammann (VFT) equation for portraying the primary relaxation time or shear viscosity indicated a possible phase transition, hidden below the glass transition temperature (T(g)). Recently Hecksher [Nat. Phys. 4, 737 (2008)] delivered strong empirical arguments that VFT description lacks a direct experimental basis and thus theories not predicting a dynamic divergence should be focused on. We present clear evidence for a superiority of critical-like divergent equation τ(T)=τ(0)(T-T(C))(-ϕ) and T(C)<T(g) for liquid crystalline (LC) glass formers and orientationally disordered crystals (ODIC). Such dependence was already known for spin-glasslike systems and the dynamical scaling model, although the latter was hardly explored so far. The pressure-related behavior is also discussed. Results obtained support arguments for the suggested direct link between critical phenomena and vitrification [Tanaka, Nat. Mater. 9, 324 (2010)]. LCs and ODICs may be considered as simple experimental model systems for the structural glass formers group.
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Affiliation(s)
- Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics, Polish Academy of Sciences, ul. Sokołowska 27/39, 01-143 Warsaw, Poland
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250
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Syutkin VM, Vyazovkin VL, Korolev VV, Grebenkin SY. Length scale of heterogeneities in glassy propylene carbonate probed by oxygen diffusion. J Chem Phys 2010; 133:074501. [PMID: 20726646 DOI: 10.1063/1.3469775] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A new method using the quenching of guest molecule phosphorescence by molecular oxygen is proposed for determination of heterogeneity size in glassy matrixes. The method is based on the high sensitivity of the diffusion of oxygen molecules to spatial density fluctuations. Phenanthrene phosphorescence decay was monitored at different concentrations of molecular oxygen in propylene carbonate below T(g). An unusual dependence of the phosphorescence decay on oxygen concentration was observed: an increase in the concentration leads to anomalously large increase in the quenching rate at short times. This dependence is considered to be caused by matrix heterogeneity. To describe the phosphorescence decay, we use a model of glass as a heterogeneous medium where oxygen jump rates are spatially correlated. The length of spatial correlation for the jump rates is taken as heterogeneity size. Using the model, the value of 1.5+/-0.5 nm was obtained for the size of structural heterogeneities in glassy propylene carbonate. The dispersion of barriers for oxygen jumps is estimated to be 4+/-1 kJ/mole and the average barrier energy is found to be 50 kJ/mole.
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Affiliation(s)
- V M Syutkin
- Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russian Federation.
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