Dynamics and structure of an aging binary colloidal glass

Lynch, Jennifer M.; Cianci, Gianguido C.; Weeks, Eric R.

doi:10.1103/physreve.78.031410

Cited by 63 publications

(97 citation statements)

References 55 publications

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“…These features are seen in metallic glasses [148,149] but also in silicates [152]), and find strong analogies with the aging dynamics of more softer glassy materials [502], while also pointing stress relaxation as a universal mechanism driving the relaxation dynamics of out-of-equilibrium systems. This has been also acknowledged for a borosilicate glass showing stress relaxation under aging at T /T g ≃0.3 [105] but contradicts the qualitative mechanism sketched from density changes with aging [499].…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 74%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

100

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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: 74%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

100

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“…it differs qualitatively from the aging observed in conventional glassy materials, such as polymer and colloidal glasses [19,20]. Scattering experiments [21][22][23][24][25] report that time correlation functions are described by compressed exponential relaxations.…”

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confidence: 81%

Ultra-long-range dynamic correlations in a microscopic model for aging gels

Chaudhuri

Berthier

2017

Phys. Rev. E

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We use large-scale computer simulations to explore the nonequilibrium aging dynamics in a microscopic model for colloidal gels. We find that gelation resulting from a kinetically-arrested phase separation is accompanied by 'anomalous' particle dynamics revealed by superdiffusive particle motion and compressed exponential relaxation of time correlation functions. Spatio-temporal analysis of the dynamics reveals intermittent heterogeneities producing spatial correlations over extremely large length scales. Our study is the first microscopically-resolved model reproducing all features of the spontaneous aging dynamics observed experimentally in soft materials.Understanding the complex mechanisms underlying the formation and stability of colloidal gels remains a challenge, despite the diversity of existing applications exploiting their mechanical properties. Gels are lowdensity structures forming percolating networks, with bonds that are either permanent (chemical gels) or transient (physical gels) [1][2][3][4][5][6]. A prevalent method to form physical gels follows a nonequilibrium route by quenching a homogeneous fluid into a phase coexistence region [1,[7][8][9][10][11][12], which generates bicontinuous structures. When the dense phase forms an amorphous solid, the phase separation is kinetically hindered [13][14][15][16] and a gel forms. The microscopic dynamical and structural properties of these nonequilibrium gels evolve slowly with time.This aging dynamics has been the subject of many experimental studies, which established that aging in colloidal gels is 'anomalous' [17,18], i.e. it differs qualitatively from the aging observed in conventional glassy materials, such as polymer and colloidal glasses [19,20]. Scattering experiments [21][22][23][24][25] report that time correlation functions are described by compressed exponential relaxations. Such behaviour differs from the (exponential) diffusive dynamics in simple liquids or the (stretched exponential) decay observed in glassy fluids [26]. In addition, compressed exponentials are seen to emerge only for large enough displacements, with the relaxation timescale τ (q) crossing over from τ ∼ q −2 , characteristics of diffusion, to τ ∼ q −1 , characteristic of ballistic dynamics, with decreasing the scattering wavevector q. Finally, spatiallyresolved dynamic measurements revealed the existence of long-ranged correlations extending up to the system size [27,28], again contrasting with the much smaller-ranged dynamic heterogeneity observed in glassy materials [29]. Such peculiar behaviour is hypothesized to follow from the infrequent release of 'internal stresses' that relax the fractal network [18], but this interpretation remains to be confirmed by direct observation. This overall phenomenology has been reported for laponite, carbon black, micellar polycrystals, multilamellar vesicles, implying it is generic to a large class of soft materials [18].A microscopic perspective via theoretical modeling is also missing. To study this problem, one needs a model with a...

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“…This builds on extensive studies using light scattering techniques 12,13 , and, more recently, microscopy techniques [14][15][16] . The most widely studied system is that of particles which behave as hard spheres 17 .…”

Section: Introductionmentioning

confidence: 99%

Dynamics of hard sphere suspensions using dynamic light scattering and X-ray photon correlation spectroscopy: Dynamics and scaling of the intermediate scattering function

Martinez

Thijssen

Zontone

et al. 2011

The Journal of Chemical Physics

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Intermediate Scattering Functions (ISF's) are measured for colloidal hard sphere systems using both Dynamic Light Scattering (DLS) and X-ray Photon Correlation Spectroscopy (XPCS). We compare the techniques, and discuss the advantages and disadvantages of each. Both techniques agree in the overlapping range of scattering vectors. We investigate the scaling behaviour found by Segre and Pusey 1 but challenged by Lurio et al. 2 . We observe a scaling behaviour over several decades in time but not in the long time regime. Moreover, we do not observe long time diffusive regimes at scattering vectors away from the peak of the structure factor and so question the existence of a long time diffusion coefficients at these scattering vectors.

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Dynamics and structure of an aging binary colloidal glass

Cited by 63 publications

References 55 publications

Relaxation and physical aging in network glasses: a review

Relaxation and physical aging in network glasses: a review

Ultra-long-range dynamic correlations in a microscopic model for aging gels

Dynamics of hard sphere suspensions using dynamic light scattering and X-ray photon correlation spectroscopy: Dynamics and scaling of the intermediate scattering function

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