Microscopic Picture of Aging in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>SiO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Vollmayr-Lee, Katharina; Bjorkquist, Robin; Chambers, Landon

doi:10.1103/physrevlett.110.017801

Cited by 27 publications

(63 citation statements)

References 22 publications

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“…In silica, aging seems to result from single particle trajectories and jump events corresponding to the escape of an atom from the cage formed by its neighbors [490]. It has been found that the only t w -dependent microscopic quantity is the number of jumping particles per unit time [494], and this quantity has been found to decreases with age.…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

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Abstract. Recent progresses in the description of glassy relaxation and ageing are reviewed for the wide class of network-forming materials such as GeO 2 , Ge x Se 1−x , silicates (SiO 2 -Na 2 O) or borates (B 2 O 3 -Li 2 O), all of them having an important usefulness in domestic, geological or optoelectronic applications. A brief introduction of the glass transition phenomenology is given, together with the salient features that are revealed both from theory and experiments. Standard experimental methods used for the characterization of the slowing down of the dynamics are reviewed. We then discuss the important role played by aspect of network topology and rigidity for the understanding of the relaxation of the glass transition, while also permitting analytical predictions of glass properties from simple and insightful models based on the network structure. We also emphasize the great utility of computer simulations which probe the dynamics at the molecular level, and permit to calculate various structure-related functions in connection with glassy relaxation and the physics of ageing which reveals the off-equilibrium nature of glasses. We discuss the notion of spatial variations of structure which leads to the picture of "dynamic heterogeneities", and recent results of this important topic for network glasses are also reviewed.PACS numbers: 61.43. Fs, 64.70.kj Relaxation and physical ageing in network glasses 2 Figure 1. Typical network-forming glasses: a) A stoichiometric glass former (SiO 2 , B 2 S 3 ) whose structure and network connectivity can be altered by the addition (b) of 2-fold coordinated atoms (usually chalcogens, S, Se) that lead to cross-linked chains. The structure can also be depolymerized (c) by the addition of a network modifier (alkali oxides or chalcogenides, Na 2 O, Li 2 S, etc.). Glassy dynamics depends strongly on the network topology, i.e. the way bonds and angles arrange to lead to a connected atomic network. Note that only chalcogenides can produce a mixture of these three kinds of basic networks, e.g. (1-x)Ge y Se 1−y -xAg 2 Se [2], and for the latter system x=0 corresponds to case (b), y=33% corresponds to case (c), and both conditions together (x=0,y=33 %) to case (a).

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Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

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“…Silica is known to locally form well-defined tetrahedra of SiO 4 , where silicon forms the tetrahedral center with oxygen surrounding. Each oxygen, in turn, bridges the tetrahedral corners, bonding between two silicon centers.…”

Section: Introductionmentioning

confidence: 99%

“…Molecular dynamics (MD) has been extensively used to study silicate glasses [1][2][3] in areas of nanosecond aging of silica [4][5][6], pressure and shear response [7][8][9], and cooling-rate effects [10][11][12][13]. In this work, we use the BKS interatomic potential [14], which has been used frequently to study the glass properties of silica, and has been demonstrated to capture experimentally observed behavior.…”

Section: Introductionmentioning

confidence: 99%

Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dynamics

Lane

2015

Phys. Rev. E

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We have conducted extremely long molecular dynamics (MD) simulations of glasses to microsecond times, which close the gap between experimental and atomistic simulation timescales by 2 to 3 order of magnitude. Static, thermal, and structural properties of silica glass are reported for glass cooling rates down to 5 × 10 9 K/s and viscoelastic response in silica melts and glasses are studied over 9 decades of time. We present results from relaxation of hydrostatic compressive stress in silica and show that time-temperature superposition holds in these systems for temperatures from 3500 K to 1000 K.

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“…Such a cage-jump phenomenon has been proposed to be the building block of dynamical heterogeneity [26,27], aging dynamics [28], and long-time diffusion [29]. Cage jumps happen because along some specific directions, e.g.…”

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confidence: 99%

“…We follow the same protocol as in [28] to identify cage jumps and define T j as the lowest temperature above which cage jumps occur within a simulation time of 3000. As shown in Fig.…”

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confidence: 99%

Order parameter for structural heterogeneity in disordered solids

Tong

2014

Phys. Rev. E

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We construct a new order parameter from the normal modes of vibration, based on the consideration of energy equipartition, to quantify the structural heterogeneity in disordered solids. The order parameter exhibits strong spatial correlations with low-temperature single particle dynamics and local structural entropy. To characterize the role of particles with the most defective local structures identified by the order parameter, we pin them and study how properties of disordered solids respond to the pinning. It turns out that these particles are responsible to the quasilocalized low-frequency vibration, instability, softening, and nonaffinity of disordered solids.PACS numbers: 63.50. Lm,61.43.Bn, The nature of disordered solids, e.g. glasses and sandpiles, remains elusive and a major challenge to condensed matter physics [1][2][3]. Compared to crystalline solids, the absence of long-range structural order makes it difficult to interpret properties of disordered solids analytically. What makes it more difficult is the spatial heterogeneity of the structural disorder. It has been evidenced that the heterogeneous disorder greatly contributes to abnormal properties of disordered materials, e.g. the anomalous low-frequency excitations and consequent unusual thermal properties [4], heterogeneous mechanical response to perturbations [5][6][7], and dynamical heterogeneity of supercooled liquids [8][9][10][11]. Therefore, how to correctly describe the heterogeneous disorder is the key to develop the theory of disordered solids.For crystals, it has been well-known that dislocations are triggers of the instability, which have lower bond orientational order than perfect lattice sites and can thus be easily identified. The bond orientational order has been applied to identify defective spots in weakly disordered solids [10][11][12][13]. However, this approach fails to describe the structural heterogeneity of strongly disordered solids, e.g. systems with large particle size dispersity, in which the locally favored geometric structure is no longer a perfect crystal [11,13]. An alternate order parameter is thus needed to pick out "defective" structures in disordered solids, which must capture the heterogeneous dynamics correctly and be responsible to the special properties of disordered solids.Inspired by recent observations that low-frequency quasilocalized modes of vibration are correlated with particle rearrangements in disordered systems [9, 14-17], we construct an order parameter Ψ at single particle level from normal modes of vibration, based on the assumption of energy equipartition. This new order parameter is validated by showing excellent spatial correlations with low-temperature dynamics and structural entropy. In order to figure out the role of particles with the largest Ψ, i.e. particles with the most defective local structures, we measure the system response to the pinning of these particles. Interestingly, the pinning remarkably eliminates the low-frequency quasilocalized modes, strengthens the system stability ...

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Microscopic Picture of Aging inSiO2

Cited by 27 publications

References 22 publications

Relaxation and physical aging in network glasses: a review

Relaxation and physical aging in network glasses: a review

Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dynamics

Order parameter for structural heterogeneity in disordered solids

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