Phase transitions of CO2 confined in nanometer pores as revealed by positronium annihilation

J. A. Duffy*, N. J. Wilkinson, H. M. Fretwell, M. A. Alam, R. Evans

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

57 Citations (Scopus)


The results of a comprehensive positronium annihilation study of the phase behaviour of carbon dioxide in porous Vycor glass are presented. Isobaric measurements of the 3 gamma:2 gamma annihilation ratio show that on cooling, the gas-liquid phase boundary is raised by ∼5 K while the liquid-solid transition is depressed by ∼12 K relative to the bulk. The resulting phase diagram suggests the existence of a 'triple point' of the confined fluid at a temperature ∼10 K and a pressure ∼2 bar below the bulk triple point.

Original languageEnglish
Article number003
JournalJournal of Physics Condensed Matter
Issue number50
Publication statusPublished - 1995

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