Origin of glass fragility and Vogel temperature emerging from Molecular dynamics simulations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F18%3A43917257" target="_blank" >RIV/60461373:22310/18:43917257 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.jnoncrysol.2018.06.012" target="_blank" >http://dx.doi.org/10.1016/j.jnoncrysol.2018.06.012</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jnoncrysol.2018.06.012" target="_blank" >10.1016/j.jnoncrysol.2018.06.012</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Origin of glass fragility and Vogel temperature emerging from Molecular dynamics simulations

Popis výsledku v původním jazyce

Vitreous silica is modelled by Molecular dynamics. Glass structure is transferred into undirected graph and decomposed into disjoint structural units that are ideally mixed to calculate configuration entropy. A good agreement of the approach with experimental heat capacity drop at T-g is demonstrated. Entropy is related with structural evolution of the obtained units; among them dangling oxygen dominantly effects low-temperature course of entropy. Configuration entropy is fitted by two parabolas; the one, corresponding to lower temperatures, introduces temperature T*, at which structure is completely frozen. It is proposed T* is a counterpart of Vogel temperature in Vogel-Fulcher-Tammann (VFT) equation. A new model of viscosity is introduced as the combination of the quadratic dependence of configuration entropy and Adam and Gibbs equation. The model removes the singularity at Vogel temperature, predicts existence of strong and fragile glasses, and provides a base for fitting viscosities of real glasses. Fragility is associated with quickness of structural response to temperature changes and the distance between T-g and T*. The validity of the model is demonstrated on experimental data of viscosity for SiO2 and B2O3 glasses.

Název v anglickém jazyce

Origin of glass fragility and Vogel temperature emerging from Molecular dynamics simulations

Popis výsledku anglicky

Vitreous silica is modelled by Molecular dynamics. Glass structure is transferred into undirected graph and decomposed into disjoint structural units that are ideally mixed to calculate configuration entropy. A good agreement of the approach with experimental heat capacity drop at T-g is demonstrated. Entropy is related with structural evolution of the obtained units; among them dangling oxygen dominantly effects low-temperature course of entropy. Configuration entropy is fitted by two parabolas; the one, corresponding to lower temperatures, introduces temperature T*, at which structure is completely frozen. It is proposed T* is a counterpart of Vogel temperature in Vogel-Fulcher-Tammann (VFT) equation. A new model of viscosity is introduced as the combination of the quadratic dependence of configuration entropy and Adam and Gibbs equation. The model removes the singularity at Vogel temperature, predicts existence of strong and fragile glasses, and provides a base for fitting viscosities of real glasses. Fragility is associated with quickness of structural response to temperature changes and the distance between T-g and T*. The validity of the model is demonstrated on experimental data of viscosity for SiO2 and B2O3 glasses.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20504 - Ceramics

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Non-crystalline Solids

ISSN

0022-3093

e-ISSN

—

Svazek periodika

498

Číslo periodika v rámci svazku

říjen

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

9

Strana od-do

109-117

Kód UT WoS článku

000440389500015

EID výsledku v databázi Scopus

—