It is an experimental fact that in the neighborhood of melting curves, including those measured at above-critical pressures and temperatures, all fluids have some short- and intermediate-range order and their excitation spectra contain high-frequency shear waves. At high pressure both smooth and sharp first-order phase transformations involving changes in liquid structure and properties can occur between various liquid states. However, at sufficiently high temperatures any liquid loses its identity and turns into an unstructured dense gas in which only longitudinal waves can propagate. This paper discusses theoretical and experimental evidence for the existence of a boundary between a 'solid-like' melt and a dense gas at supercritical pressures.

Keywords: supercritical fluids, high pressures, phase transformations, dynamical crossover PACS: 61.20.−p, 62.10.+s, 62.50.−p, 64.70.Ja (all) DOI: 10.3367/UFNe.2016.12.038118 URL: https://ufn.ru/en/articles/2017/9/i/ 000417704200009 2-s2.0-85041007131 2017PhyU...60..954B Citation: Brazhkin V V "Phase transformations in liquids and the liquid—gas transition in fluids at supercritical pressures" Phys. Usp. 60 954–957 (2017) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks @article{Brazhkin:2017, author = {V. V. Brazhkin}, title = {Phase transformations in liquids and the liquid—gas transition in fluids at supercritical pressures}, publisher = {Physics-Uspekhi}, year = {2017}, journal = {Phys. Usp.}, volume = {60}, number = {9}, pages = {954-957}, url = {https://ufn.ru/en/articles/2017/9/i/}, doi = {10.3367/UFNe.2016.12.038118} } Received: 5th, April 2017, accepted: 21st, December 2016 Оригинал: Бражкин В В «Фазовые превращения в жидкостях и переход жидкость—газ во флюидах при сверхкритических давлениях» УФН 187 1028–1032 (2017); DOI: 10.3367/UFNr.2016.12.038118