Molecular dynamics simulations of structural changes in mixed alkali (Li–K) silicate glasses

Park, Byeongwon; Cormack, Alastair N.

doi:10.1016/s0022-3093(99)00430-5

Cited by 56 publications

(46 citation statements)

References 22 publications

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“…The term jump implies that the time scale it takes to cross the saddle is much shorter than the time scale the ions fluctuate within the individual sites. This conclusion is in qualitative agreement with previous simulations [15,24,40,41,42] and also agrees with the appearance of the trajectories in Fig.1. The first minimum of G s (r, t) around r min ≈ 1.5Å can be used to distinguish local vibrational dynamics (|∆r(t)| < 1.5Å) and long-range dynamics (|∆r(t)| > 1.5Å).…”

Section: Dynamicssupporting

confidence: 93%

“…In this paper we present computer simulations for lithium silicate following this general approach. As an example we take the lithium dynamics in (Li 2 O)(SiO 2 ) [13,14,15]. In contrast to most earlier work on this system the present computer generation allows one to study the lithium dynamics in the low-temperature dispersive regime in equilibrium conditions.…”

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confidence: 99%

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Characterization of the complex ion dynamics in lithium silicate glasses via computer simulations

Heuer¹,

Kunow²,

Vogel³

et al. 2002

Phys. Chem. Chem. Phys.

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We present results of molecular dynamics simulations on lithium metasilicate over a broad range of temperatures for which the silicate network is frozen in but the lithium ions can still be equilibrated. The lithium dynamics is studied via the analysis of different correlation functions. The activation energy for the lithium mobility agrees very well with experimental data. The correlation of the dynamics of adjacent ions is weak. At low temperatures the dynamics can be separated into local vibrational dynamics and hopping events between adjacent lithium sites. The derivative of the mean square displacement displays several characteristic time regimes. They can be directly mapped onto respective frequency regimes for the conductivity. In particular it is possible to identify time regimes dominated by localized dynamics and longrange dynamics, respectively. The question of time-temperature superposition is discussed for the mean square displacement and the incoherent scattering function.

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Section: Dynamicssupporting

confidence: 93%

mentioning

confidence: 99%

Characterization of the complex ion dynamics in lithium silicate glasses via computer simulations

Heuer¹,

Kunow²,

Vogel³

et al. 2002

Phys. Chem. Chem. Phys.

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“…It may come as a surprise that the time τ f ree during which a site is vacant is not much longer than the transition time t ch between adjacent sites. This reflects strongly cooperative dynamics, as stressed in previous simulation work 19,39 . Interestingly, the distributions are significantly broader for the MA system.…”

Section: Site Propertiessupporting

confidence: 73%

“…Proof for some structure at the scale of these channels can also be found in measurements of the dynamic structure factor 14,15 . One of the most important MD results for MA glasses is the observation that ions only rarely jump into sites vacated by the other species 16 and that the site characteristics of both species are very different 17,18,19 .…”

Section: Introductionmentioning

confidence: 99%

Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

Lammert¹,

Heuer²

2005

Phys. Rev. B

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The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed-alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronger and more retarding for the larger ions, the smaller ions can be temporarily accommodated. Also correlations between unlike as well as like cations are demonstrated that support cooperative behavior.

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“…I. The properties of the distributions are compatible with earlier results, determined both for sites 20 , and without reference to ion sites 9,33,34,35 . The influence of interactions with both cations and network on the shape of the site-energy distributions is demonstrated in Fig.…”

Section: Properties Of Average Site-energiessupporting

confidence: 89%

The cationic energy landscape in alkali silicate glasses: Properties and relevance

Lammert

Banhatti

Heuer

2009

The Journal of Chemical Physics

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Individual cationic site-energies are explicitly determined from molecular dynamics simulations of alkali silicate glasses, and the properties and relevance of this local energetics to ion transport are studied. The absence of relaxations on the timescale of ion transport proves the validity of a static description of the energy landscape, as it is generally used in hopping models. The Coulomb interaction among the cations turns out essential to obtain an average energy landscape in agreement with typical simplified hopping models. Strong correlations exist both between neighboring sites and between different energetic contributions at one site, and they shape essential characteristics of the energy landscape. A model energy landscape with a single vacancy is used to demonstrate why average site-energies, including the full Coulomb interaction, are still insufficient to describe the site population of ions, or their dynamics. This model explains how the relationship between energetics and ion dynamics is weakened, and thus establishes conclusively that a hopping picture with static energies fails to capture all the relevant information. It is therefore suggested that alternative simplified models of ion conduction are needed.

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Molecular dynamics simulations of structural changes in mixed alkali (Li–K) silicate glasses

Cited by 56 publications

References 22 publications

Characterization of the complex ion dynamics in lithium silicate glasses via computer simulations

Characterization of the complex ion dynamics in lithium silicate glasses via computer simulations

Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

The cationic energy landscape in alkali silicate glasses: Properties and relevance

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