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Metastable phases, phase transformations, and phase diagrams in physics and chemistry


Institute for High Pressure Physics, Russian Academy of Sciences, Kaluzhskoe shosse 14, Troitsk, Moscow, 108840, Russian Federation

Concepts of a ’phase’ and a ’phase transition’ are discussed for stable and metastable states of matter. While condensed matter physics primarily considers equilibrium states and treats metastable phases as exceptions, organic chemistry overwhelmingly deals with metastable states. It is emphasized that many simple light-element compounds — including most hydrocarbons; nitrogen oxides, hydrides, and carbides; carbon monoxide CO; alcohols and glycerin — are also metastable at normal pressure in the sense that they do not correspond to a minimum Gibbs free energy for a given chemical composition. At moderate temperatures and pressures, the phase transformations for these metastable phases are reversible with the fulfilment of all laws of equilibrium thermodynamics over the entire range of experimentally accessible times. At sufficiently high pressures (> 1-10 GPa), most of the metastable molecular phases irreversibly transform to lower-energy polymer phases, stable or metastable. These transitions do not correspond to the equality of the Gibbs free energy for the involved phases before and after the transition and so they are not first-order in the ’classical’ sense. At normal pressure, the resulting polymer phases can exist at temperatures above the melting point of the original metastable molecular phase, as the examples of polyethylene and polymerized CO dramatically illustrate. As pressure is increased further to 20-50 GPa, the PV contribution to Gibbs free energy gives rise to stable high-density atomic phases. Many of the intermediateenergy polymer phases can likely be synthesized by methods of ’classical’ chemistry at normal pressure.

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Fulltext is also available at DOI: 10.1070/PU2006v049n07ABEH006013
PACS: 05.70.Fh, 05.70.Lh, 64.60.−i (all)
DOI: 10.1070/PU2006v049n07ABEH006013
URL: https://ufn.ru/en/articles/2006/7/c/
000242169200003
2-s2.0-33751341735
2006PhyU...49..719B
Citation: Brazhkin V V "Metastable phases, phase transformations, and phase diagrams in physics and chemistry" Phys. Usp. 49 719–724 (2006)
BibTexBibNote ® (generic) BibNote ® (RIS)MedlineRefWorks
TY JOUR
TI Metastable phases, phase transformations, and phase diagrams in physics and chemistry
AU Brazhkin, V. V.
PB Physics-Uspekhi
PY 2006
JO Physics-Uspekhi
JF Physics-Uspekhi
JA Phys. Usp.
VL 49
IS 7
SP 719-724
UR https://ufn.ru/en/articles/2006/7/c/
ER https://doi.org/10.1070/PU2006v049n07ABEH006013

Оригинал: Бражкин В В «Метастабильные фазы, фазовые превращения и фазовые диаграммы в физике и химии» УФН 176 745–750 (2006); DOI: 10.3367/UFNr.0176.200607d.0745

References (23) Cited by (38)

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