Relaxation of silica glass surfaces before and after stress modification in a wet and dry atmosphere

Molecular dynamics simulations

Edmund B. Webb, Steve Garofalini

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Previous molecular dynamics simulations have shown that compression of silica glass surfaces occurs upon formation of an interface with a model crystal and that a structural change caused by this process is retained after glass and crystal are separated. The remnant structural modification caused by this stress was an increase in the concentration of siloxane bond angles less than 150° in the near surface region of the glass. It was expected that the structural modification associated with interface formation and separation could represent an increase in the concentration of less stable siloxane bonds, particularly in the presence of water molecules. It was also recognized that a decreased stability could indicate greater reactivity with water molecules. Thus, water reaction on silica surfaces was simulated before and after stress modification and the subsequent structural relaxations in the glass surface were observed. Decreased stability, represented by a greater number of bond ruptures, existed after interface formation and removal. These bond ruptures were Si-O bonds breaking and reforming siloxane bonds with an angle nearer the average and also Si-O bonds breaking to react with water forming silanols. A greater number of silanols formed after interface formation and removal than before, demonstrating a greater reactivity with water after interface formation and separation.

Original languageEnglish
Pages (from-to)47-57
Number of pages11
JournalJournal of Non-Crystalline Solids
Volume226
Issue number1-2
Publication statusPublished - May 1998

Fingerprint

silica glass
Fused silica
Molecular dynamics
Siloxanes
molecular dynamics
siloxanes
atmospheres
Water
Computer simulation
water
simulation
Glass
glass
reactivity
Structural relaxation
Crystals
Molecules
Reforming reactions
Silicon Dioxide
crystals

ASJC Scopus subject areas

  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials

Cite this

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abstract = "Previous molecular dynamics simulations have shown that compression of silica glass surfaces occurs upon formation of an interface with a model crystal and that a structural change caused by this process is retained after glass and crystal are separated. The remnant structural modification caused by this stress was an increase in the concentration of siloxane bond angles less than 150° in the near surface region of the glass. It was expected that the structural modification associated with interface formation and separation could represent an increase in the concentration of less stable siloxane bonds, particularly in the presence of water molecules. It was also recognized that a decreased stability could indicate greater reactivity with water molecules. Thus, water reaction on silica surfaces was simulated before and after stress modification and the subsequent structural relaxations in the glass surface were observed. Decreased stability, represented by a greater number of bond ruptures, existed after interface formation and removal. These bond ruptures were Si-O bonds breaking and reforming siloxane bonds with an angle nearer the average and also Si-O bonds breaking to react with water forming silanols. A greater number of silanols formed after interface formation and removal than before, demonstrating a greater reactivity with water after interface formation and separation.",
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T2 - Molecular dynamics simulations

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N2 - Previous molecular dynamics simulations have shown that compression of silica glass surfaces occurs upon formation of an interface with a model crystal and that a structural change caused by this process is retained after glass and crystal are separated. The remnant structural modification caused by this stress was an increase in the concentration of siloxane bond angles less than 150° in the near surface region of the glass. It was expected that the structural modification associated with interface formation and separation could represent an increase in the concentration of less stable siloxane bonds, particularly in the presence of water molecules. It was also recognized that a decreased stability could indicate greater reactivity with water molecules. Thus, water reaction on silica surfaces was simulated before and after stress modification and the subsequent structural relaxations in the glass surface were observed. Decreased stability, represented by a greater number of bond ruptures, existed after interface formation and removal. These bond ruptures were Si-O bonds breaking and reforming siloxane bonds with an angle nearer the average and also Si-O bonds breaking to react with water forming silanols. A greater number of silanols formed after interface formation and removal than before, demonstrating a greater reactivity with water after interface formation and separation.

AB - Previous molecular dynamics simulations have shown that compression of silica glass surfaces occurs upon formation of an interface with a model crystal and that a structural change caused by this process is retained after glass and crystal are separated. The remnant structural modification caused by this stress was an increase in the concentration of siloxane bond angles less than 150° in the near surface region of the glass. It was expected that the structural modification associated with interface formation and separation could represent an increase in the concentration of less stable siloxane bonds, particularly in the presence of water molecules. It was also recognized that a decreased stability could indicate greater reactivity with water molecules. Thus, water reaction on silica surfaces was simulated before and after stress modification and the subsequent structural relaxations in the glass surface were observed. Decreased stability, represented by a greater number of bond ruptures, existed after interface formation and removal. These bond ruptures were Si-O bonds breaking and reforming siloxane bonds with an angle nearer the average and also Si-O bonds breaking to react with water forming silanols. A greater number of silanols formed after interface formation and removal than before, demonstrating a greater reactivity with water after interface formation and separation.

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