Τίτλος:
On the Different Faces of the Supercritical Phase of Water at a Near-Critical Temperature: Pressure-Induced Structural Transitions Ranging from a Gaslike Fluid to a Plastic Crystal Polymorph
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
The present study reports a systematic analysis of a wide variety of structural, thermodynamic, and dynamic properties of supercritical water along the near-critical isotherm ofT= 1.03Tcand up to extreme pressures, using molecular dynamics and Monte Carlo simulations. The methodology employed provides solid evidence about the existence of a structural transition from a liquidlike fluid to a compressed, tightly packed liquid, in the density and pressure region around 3.4ρcand 1.17 GPa, introducing an alternative approach to locate the crossing of the Frenkel line. Around 8.5 GPa another transition to a face-centered-cubic plastic crystal polymorph with density 5.178ρcis also observed, further confirmed by Gibbs free energy calculations using the two-phase thermodynamic model. The isobaric heat capacity maximum, closely related to the crossing of the Widom line, has also been observed around 0.8ρc, where the local density augmentation is also maximized. Another structural transition has been observed at 0.2ρc, related to the transformation of the fluid to a dilute gas at lower densities. These findings indicate that a near-critical isotherm can be divided into different domains where supercritical water exhibits distinct behavior, ranging from a gaslike one to a plastic crystal one. © 2021 American Chemical Society
Συγγραφείς:
Skarmoutsos, I.
Henao, A.
Guardia, E.
Samios, J.
Περιοδικό:
JOURNAL OF PHYSICAL CHEMISTRY B: CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES, AND BIOPHYSICAL (THE)
Εκδότης:
American Chemical Society
Λέξεις-κλειδιά:
Free energy; Gibbs free energy; Intelligent systems; Isotherms; Monte Carlo methods; Specific heat, Critical isotherms; Critical temperatures; Crystal polymorph; Plastic crystals; Pressure-induced structural transitions; Structural thermodynamics; Structural transitions; Supercritical phasis; Supercritical water; Systematic analysis, Molecular dynamics
DOI:
10.1021/acs.jpcb.1c05053
