Structure and Speciation in Hydrous Silica Melts. 2. Pressure Effects

被引：6

作者：

Anderson, Kelly E. ^{[1
,2
]}

Grauvilardell, Lorna C. ^{[1
,2
]}

Hirschmann, Marc M. ^{[3
]}

Siepmann, J. Ilja ^{[1
,2
]}

机构：

[1] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA

[2] Univ Minnesota, Dept Chem Engn & Mat Sci, Minneapolis, MN 55455 USA

[3] Univ Minnesota, Dept Geol & Geophys, Minneapolis, MN 55455 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY B | 2008年 / 112卷 / 41期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1021/jp802255y

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The effect of pressure on structure and water speciation in hydrated liquid silica is examined over a range of temperatures and compositions. The Feuston-Garofalini (FG) potential is used in isobaric-isothermal Monte Carlo simulations carried out at four pressures (0.25, 1.0, 2.5, and 10 GPa) for seven temperatures. (2000 <= T <= 9000 K) and five compositions (0.0 <= x(w) <= 0.4). The FG potential yields a stable melt phase for p >= 1.0 GPa and/or x(w) <= 0.1 for all temperatures. The volume minimum seen in previous simulations of pure and hydrated liquid silica using the FG potential persists up to 2.5 GPa but is no longer evident at 10 GPa. This is correlated with gradual structural changes of the liquid up to 2.5 GPa and with more significant changes at 10 GPa. Even at high overall concentrations of water (x(w) = 0.4), only about 2% of oxygen atoms are present as molecular water species at the lowest temperature. This percentage decreases with increasing pressure and temperature.

引用

页码：13015 / 13021

页数：7

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