Fluid phases of argon
  A phase diagram of argon based upon percolation transition loci determined from literature experimental density-pressure 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 two 2nd-order percolation transition loci, and a gas phase. Intersection of two percolation loci in the p-T plane thermodynamically defines an equilibrium line of critical density states. 
Leslie V. Woodcock
cond-mat.stat-mech