TITLE:
Fluid phases of argon: A debate on the absence of van der Waals’ “critical point”
AUTHORS:
Leslie V. Woodcock
KEYWORDS:
Critical Point; Supercritical Fluids; Liquid Phase
JOURNAL NAME:
Natural Science,
Vol.5 No.2,
February
18,
2013
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 = Tc, and the single mesophase
for T > Tc. A debate on the absence of a van der Waals critical
point in the Gibbs p-T density surface is appended.