Generation of glass SiO2 structures by various cooling rates: A molecular-dynamics study

Lee, Byoung Min; Baik, Hong Koo; Seong, Baek-Seok; Munetoh, Shinji; Motooka, Teruaki

doi:10.1016/j.commatsci.2006.01.003

Cited by 24 publications

(14 citation statements)

References 27 publications

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“…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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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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“…A higher density of Ce dopants would require a shorter diffusion path for the carriers, giving less likelihood that they encounter a trap befor reaching an activator (Ce) atom [7]. However, much previous research has been devoted to removing dangling bonds in silica via control of the glass processing procedure [30,10,37], so it is unlikely that the remaining (mostly Q 3 ) hole traps can be removed without modification of the glass composition. Furthermore, the applicability of direct atomistic simulations of the glass manufacturing processes to search for such opportunities is probably limited, since the relevant timescales are much longer than accessible even with classical potentials.…”

Section: Discussionmentioning

confidence: 99%

Hole traps in sodium silicate: First-principles calculations of the mobility edge

Adelstein

Olson

Lordi

2015

Journal of Non-Crystalline Solids

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The structure and properties of (Na 2 O) 0.30 (SiO 2) 0.70 sodium silicate glass are studied by combined ab-initio and classical molecular dynamics simulations to identify the sources of electronic traps in the band gap. Structures from classical molecular dynamics melt-quench simulations are taken as initial configurations for first-principles density functional theory structural relaxation, from which electronic properties are determined. An ensemble of thirty glass structures, each containing 660 atoms, is prepared in order to perform statistical analyses. The inverse participation ratio is used as a metric to characterize localized states in the band gap and determine the mobility edge. Structures with varying amounts of local disorder (traps) are compared. The most localized and highest energy trap states are due to Si atoms with 2-3 non-bridging oxygen atoms. Control of the electronic properties of amorphous insulators and semiconductors is essential for the advancement of many technologies, such as photovoltaics and scintillators, for which the present analysis is indispensable.

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“…3.6 the structural reorganization produced by the thermal treatment is illustrated; it can be seen that there is no a regular distribution of the particles in the amorphous system. with information collected using NMR and other computer simulations [36,61]. Note that the distributions at 0 K are as expected to be narrower than those at 300 K.…”

Section: Sample Preparation and Structural Characterizationmentioning

confidence: 60%

“…The procedure followed in this research is similar to that used by Vashishta et al [36]. [36] and other authors using different potentials [58,61]. In Fig.…”

Section: Sample Preparation and Structural Characterizationmentioning

confidence: 94%

“…Then, the system must be heated up to a high temperature simulating the liquid state, and then cooled down using high cooling rates to avoid recrystallization. The cooling can be done either directly from the liquid phase to the desired temperature or in a step-wise process, thermalizing the system at different temperatures [36,61].…”

Section: Sample Preparation and Structural Characterizationmentioning

confidence: 99%

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Structural and Mechanical Properties of Silica and Hybrid Aerogels and Xerogels Studied Using Molecular Dynamics Simulations

Murillo¹,

Sandro²

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The structural and mechanical properties of silica and hybrid aerogels and xerogels are studied using Molecular Dynamics simulations. Hybrid samples are created by adding methyl groups (CH 3) to the silica structure. Silica samples are generated expanding a dense silica glass in a simulation box of volume chosen to produce a porous sample of a specified density. The expanded glass is thermally treated using a combination of heating and cooling processes. The heating process increases the kinetic energy of the atoms in the system, which facilitates their movement throughout the system. The cooling process reduces the kinetic energy of the atoms and helps locking them in place forming the desired porous structure. A similar procedure is used to create the hybrid samples, but CH 3 −SiO 2 molecules are randomly inserted in the expanded structure before the thermal treatment of the sample. The structures are characterized estimating the fractal dimension of the samples. It is calculated using its relationship with the decay of the Pair Distribution Function of the samples in the intermediate range of structural arrangement. The fractal dimension of the samples used for this study compares favorably to the values found reported in experimental studies, which validates the preparation processes used here. The mechanical properties of the samples are obtained by modeling a tension test performed by stretching the sample along one direction. The stress vs. strain relationship is estimated for all the samples. The results reproduce trends similar to those reported from physical experiments. The computational models show that the addition of methyl groups reduces the stiffness of the structure allowing it to stretch more easily, and increasing the toughness of the samples. From the stress-strain plots is concluded that as the amount of methyl groups in the structure is increased also does the compliance of the sample, effectively making the nature of the material similar to a rubber-like material. These results are in agreement with physical experimental findings which show that adding methyl groups to silica allows compressing the samples more than 50% without destroying them. To my family, my life support.

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Generation of glass SiO2 structures by various cooling rates: A molecular-dynamics study

Cited by 24 publications

References 27 publications

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

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

Hole traps in sodium silicate: First-principles calculations of the mobility edge

Structural and Mechanical Properties of Silica and Hybrid Aerogels and Xerogels Studied Using Molecular Dynamics Simulations

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