Instantaneous normal modes analysis of amorphous and supercooled silica

Bembenek, Scott D.; Laird, Brian B.

doi:10.1063/1.1337040

Cited by 35 publications

(26 citation statements)

References 35 publications

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“…In supercooled silica, potential energy landscapes have been investigated [194,458,459,460], and have revealed that the distribution of IS energies significantly deviates from a Gaussian distribution [194], a result that seem to be connected with the progressive formation of a defect free tetrahedral network which as a ground state for the system [460]. As a result the configurational entropy S conf does not appear to extrapolate to zero at finite temperature [194,461], and this suggests the absence of a finite Kauzmann temperature (Fig.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

100

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“…We model vitreous SiO 2 ͑v-SiO 2 ͒ using the potential of van Beest, Kramer, and van Santen ͑BKS͒, 16 which has been used for many other studies on this material. [17][18][19][20][21][22][23][24][25] To describe the vibrational modes and thermal conductivity of model vitreous carbon-doped silica systems, we build on the BKS potential to include interactions that account for the incorporation of methyl groups in the material. The thermal conductivity of many glasses above the plateau can be calculated in terms of the vibrational modes of the glass, [12][13][14]26,27 the diffusivity of which may be computed by propagating wave packets, [26][27][28] and here we carry out such a calculation on the vitreous silicon dioxide systems.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity computed for vitreous silica and methyl-doped silica above the plateau

Xin

Leitner

2006

Phys. Rev. B

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The thermal conductivity of carbon-doped silicon dioxide films, fabricated to potentially serve as interlayer materials with low dielectric permittivity in small circuits, has been recently measured ͓B. C. Daly et al., Physica B 316-317, 254 ͑2002͔͒. Trends in the results were found to be inconsistent with the minimum thermal conductivity model. We report computational results for the thermal conductivity of vitreous silica and two methyl-doped silica systems of different composition, which serve as models for vitreous silica with nanoscale defects, in terms of their vibrational modes. Addition of methyl groups to silica influences the nature of the vibrational modes, particularly in the THz region. These modes, while apparently not localized, exhibit enhanced amplitude around methyl groups and are better characterized as resonant modes. We find the thermal conductivity to decrease with increased methyl doping, corresponding to a decrease in the participation ratio of the heat-carrying modes.

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“…The INM spectrum of BKS silica has been previously calculated by Bembenek and Laird [26] for equilibrium states above T 3 but no evaluation of f diff was reported. For the BKS model, the high T dynamics has been shown to be consistent with the predictions of MCT at both a qualitative [27] and a quantitative [28] level.…”

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confidence: 99%

Configuration Space Connectivity across the Fragile-to-Strong Transition in Silica

Nave

Stanley

Sciortino³

2002

Phys. Rev. Lett.

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We present a numerical analysis for SiO (2) of the fraction of diffusive direction f(diff) for temperatures T on both sides of the fragile-to-strong crossover. The T dependence of f(diff) clearly reveals this change in dynamical behavior. We find that for T above the crossover (fragile region) the system is always close to ridges of the potential energy surface (PES), while below the crossover (strong region), the system mostly explores the PES local minima. Despite this difference, the power law dependence of f(diff) on the diffusion constant, as well as the power law dependence of f(diff) on the configurational entropy, shows no change at the fragile-to-strong crossover.

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Instantaneous normal modes analysis of amorphous and supercooled silica

Cited by 35 publications

References 35 publications

Relaxation and physical aging in network glasses: a review

Relaxation and physical aging in network glasses: a review

Thermal conductivity computed for vitreous silica and methyl-doped silica above the plateau

Configuration Space Connectivity across the Fragile-to-Strong Transition in Silica

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