Title: Simulations of the surfaces of soda lime aluminoborosilicate glasses exposed to water

Abstract

Molecular dynamics simulations of 7 compositionally different sodium calcium alumino–borosilicate glasses showed formation of ⁴B and ⁵Al more consistent with experimental data without compromising the other structural features that match experimental results observed in recent simulations of these glasses. Analysis of the dry surfaces of these glasses show a lack of ⁴B in the top 5–6 Å of the surface in comparison to the bulk concentration for all glasses and no ⁵Al. Upon exposure to water, the simulations show that the ³B in the top 5–6 Å of the glasses are preferentially attacked, decreasing the number of B bonds to O originally from the glass, indicating a change in the glass network. Inclusion of all B–O bonds in the top 5–6 Å (i.e., including O from water) shows a decrease in ³B but an increase in ⁴B that is consistent with NEXAFS analysis, which the simulations show are hydroxylated. Furthermore, there is an increase in the concentration of ³Al in the dry surface in comparison to the bulk, but exposure to water converts almost all of these ³Al to ⁴Al. Hydroxyl concentrations vary from 2.6/nm² to 4.1/nm², with SiOH and BOH dominating these surface hydroxyls. Upon exposure to water, networkmore » linkages to B are preferentially ruptured. This, and the preferential loss of the nonbridging oxygen sites attached to Na, provide atomistic evidence of the initial stages of removal of B and Na from glass surfaces exposed to water.« less

Authors:

Garofalini, Stephen H.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1718-2034"

Ha, Ming Tai ^[1]; Urraca, Joelyn ^[1]

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+ Show Author Affiliations

1. Rutgers Univ., Piscataway, NJ (United States)

Publication Date:

Tue Sep 19 00:00:00 EDT 2017

Research Org.:

Rutgers Univ., New Brunswick, NJ (United States)

Sponsoring Org.:

USDOE Office of Environmental Management (EM); USDOE Office of Nuclear Energy (NE), Nuclear Energy University Program (NEUP)

OSTI Identifier:

1749869

Alternate Identifier(s):

OSTI ID: 1402086

Grant/Contract Number:  

NE0008597

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the American Ceramic Society

Additional Journal Information:

Journal Volume: 101; Journal Issue: 3; Journal ID: ISSN 0002-7820

Publisher:

American Ceramic Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Glass; simulation; structure; surface