The Open Thermodynamics Journal
2008, 2 : 95-99Published online 2008 October 17. DOI: 10.2174/1874396X00802010095
Publisher ID: TOTHERJ-2-95
Thermodynamic and Raman Spectroscopic Studies of Ar Hydrate System
Division of Chemical Engineering,
Graduate School of Engineering Science, Osaka University, 1-3,
Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
ABSTRACT
The three-phase coexisting curve of Ar hydrate + water + gas has been investigated in a pressure range up to 485 MPa and a temperature range of (279.57 to 305.32) K. The Raman spectrum of intermolecular O-O stretching vibration mode has been measured for Ar hydrate crystal along the stability boundary curve. Both the discontinuity of slope of the three-phase coexisting curve and the pressure dependence of the Raman shift reveal that two structural phase transition points exist at (281±1) MPa and (302.7±0.1) K, (456±1) MPa and (304.6±0.1) K in a pressure range up to 485 MPa for the Ar hydrate system.