Fluid phases of argon: A debate on the absence of van der Waals’ “critical point”

Leslie V. Woodcock

Manchester Institute of Biotechnology University of Manchester, Manchester, UK.

DOI: 10.4236/ns.2013.52030                

Abstract

A phase diagram of argon based upon percolation transition loci determined from literature experimental p-V isotherms, and simulation values using a Lennard-Jones model shows three fluid phases. The liquid phase spans all temperatures, from a metastable amorphous ground state at 0K, to ultra-high T. There is a supercritical mesophase bounded by percolation transition loci, and a gas phase. Intersection of two percolation loci in the p-T plane thermodynamically defines a critical line between two coexisting gas and liquid critical states at T = T_c, and the single mesophase for T > T_c. A debate on the absence of a van der Waals critical point in the Gibbs p-T density surface is appended.

Keywords

Critical Point; Supercritical Fluids; Liquid Phase

Conflicts of Interest

The authors declare no conflicts of interest.

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