Related Experiment Video
Updated: Aug 19, 2026

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems
Published on: January 24, 2014
New phase diagram of oxygen at high pressures and temperatures
Mario Santoro1, Eugene Gregoryanz, Ho-kwang Mao
1Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road N.W., Washington, D.C. 20015, USA.
Abstract:
In situ high P-T Raman measurements and optical observations of solid and fluid oxygen up to 1250 K between 8 and 25 GPa reveal the existence of a new molecular phase eta and strikingly unusual behavior of the melting curve. Three triple points were also identified in the P-T domain of the new phase. The data give a direct measure of the melting curve that greatly extends previous optical investigations. We find the melting temperature is significantly higher than that indicated by the existing phase diagram (e.g., 400 K higher at 25 GPa). Raman measurements in low and high frequency regions reveal the extent of orientational order disorder and persistence of strong intermolecular interactions in the high P-T phases.
Related Concept Videos
Phase Diagram
Phase Diagram
Phase Diagrams
pV-Diagrams
Phase Diagrams of Ternary Systems
Two Components: Liquid–Liquid Systems

