1
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Chtchelkatchev NM, Ryltsev RE, Magnitskaya MV, Gorbunov SM, Cherednichenko KA, Solozhenko VL, Brazhkin VV. Local structure, thermodynamics, and melting of boron phosphide at high pressures by deep learning-driven ab initio simulations. J Chem Phys 2023; 159:064507. [PMID: 37551816 DOI: 10.1063/5.0165948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 07/20/2023] [Indexed: 08/09/2023] Open
Abstract
Boron phosphide (BP) is a (super)hard semiconductor constituted of light elements, which is promising for high demand applications at extreme conditions. The behavior of BP at high temperatures and pressures is of special interest but is also poorly understood because both experimental and conventional ab initio methods are restricted to studying refractory covalent materials. The use of machine learning interatomic potentials is a revolutionary trend that gives a unique opportunity for high-temperature study of materials with ab initio accuracy. We develop a deep machine learning potential (DP) for accurate atomistic simulations of the solid and liquid phases of BP as well as their transformations near the melting line. Our DP provides quantitative agreement with experimental and ab initio molecular dynamics data for structural and dynamic properties. DP-based simulations reveal that at ambient pressure, a tetrahedrally bonded cubic BP crystal melts into an open structure consisting of two interpenetrating sub-networks of boron and phosphorous with different structures. Structure transformations of BP melt under compressing are reflected by the evolution of low-pressure tetrahedral coordination to high-pressure octahedral coordination. The main contributions to structural changes at low pressures are made by the evolution of medium-range order in the B-subnetwork and, at high pressures, by the change of short-range order in the P-subnetwork. Such transformations exhibit an anomalous behavior of structural characteristics in the range of 12-15 GPa. DP-based simulations reveal that the Tm(P) curve develops a maximum at P ≈ 13 GPa, whereas experimental studies provide two separate branches of the melting curve, which demonstrate the opposite behavior. Analysis of the results obtained raises open issues in developing machine learning potentials for covalent materials and stimulates further experimental and theoretical studies of melting behavior in BP.
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Affiliation(s)
- N M Chtchelkatchev
- Vereshchagin Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - R E Ryltsev
- Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences, 620016 Ekaterinburg, Russia
- Ural Federal University, 620002 Ekaterinburg, Russia
| | - M V Magnitskaya
- Vereshchagin Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - S M Gorbunov
- Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Russia
| | | | - V L Solozhenko
- LSPM-CNRS, Universite Sorbonne Paris Nord, Villetaneuse, France
| | - V V Brazhkin
- Vereshchagin Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
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2
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Ninenko SI, Brazhkin VV. Setup for precision optical studies of supercritical fluids in a wide temperature range at high pressures up to 1 GPa. Rev Sci Instrum 2022; 93:113905. [PMID: 36461523 DOI: 10.1063/5.0094655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 10/15/2022] [Indexed: 06/17/2023]
Abstract
A setup with a working volume of more than 10 mm3 has been fabricated to experimentally study the optical properties of gases, liquids, and solutions in a wide range of temperature (from 200 to 500 K) at hydrostatic pressures up to 1 GPa. The experimental parameters can be maintained with an accuracy of 0.1 K and 1.5 MPa for up to 3-4 h. To introduce laser radiation and to record spectra, high-temperature optical fibers of increased strength in a metal sheath are introduced directly into the working chamber. The primary goal of experiments is to study the Raman radiation at vibron frequencies in supercritical fluids of molecular substances (N2, CO2, CH4, etc.).
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Affiliation(s)
- S I Ninenko
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Russia
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3
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Fomin YD, Tsiok EN, Ryzhov VN, Brazhkin VV. Glass Transition in Monoatomic Systems: Dilution of One Structure or Competition between Two Structures? Russ J Phys Chem 2022. [DOI: 10.1134/s0036024422070123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Cockrell C, Brazhkin VV, Trachenko K. Universal interrelation between dynamics and thermodynamics and a dynamically driven "c" transition in fluids. Phys Rev E 2021; 104:034108. [PMID: 34654136 DOI: 10.1103/physreve.104.034108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Our very wide survey of the supercritical phase diagram and its key properties reveals a universal interrelation between dynamics and thermodynamics and an unambiguous transition between liquidlike and gaslike states. This is seen in the master plot showing a collapse of the data representing the dependence of specific heat on key dynamical parameters in the system for many different paths on the phase diagram. As a result, the observed transition is path independent. We call it a "c" transition due to the c-shaped curve parametrizing the dependence of the specific heat on key dynamical parameters. The c transition has a fixed inversion point and provides a new structure to the phase diagram, operating deep in the supercritical state (up to, at least, 2000 times the critical pressure and 50 times the critical temperature). The data collapse and path independence as well as the existence of a special inversion point on the phase diagram are indicative of either of a sharp crossover or a new phase transition in the deeply supercritical state.
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Affiliation(s)
- C Cockrell
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
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5
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Kondrin MV, Lebed YB, Brazhkin VV. Extended Defects in Graphene and Their Contribution to the Excess Specific Heat at High Temperatures. Phys Rev Lett 2021; 126:165501. [PMID: 33961452 DOI: 10.1103/physrevlett.126.165501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
The recent experiments on fast (microsecond) pulse heating of graphite suggest the existence of sharp maximum (6500 K at 1-2 GPa) on its melting curve. To check the validity of these findings, we propose to investigate the accumulation of extended in-plane defects in graphene. Such defects would contribute to thermodynamic properties of graphene and impose the upper limit on its melting temperature. We propose a type of extended defect of graphene, consisting of pentagonal and heptagonal rings with record low formation energy, whose accumulation leads to the loss of shear rigidity of graphene at temperatures above 6400 K, thus setting the upper limit on its melting temperature. We found that this model satisfactorily explains the increase of specific heat observed in the premelting region of graphite in slow (millisecond) pulse heating experiments. However, in fast (microsecond) pulse heating experiments such an increase of specific heat was not observed, which is a strong indication of overheating that takes place in these experiments.
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Affiliation(s)
- M V Kondrin
- Institute for High Pressure Physics RAS, 108840 Troitsk, Moscow, Russia
| | - Y B Lebed
- Institute for Nuclear Research RAS, 117312 Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics RAS, 108840 Troitsk, Moscow, Russia
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6
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Trachenko K, Monserrat B, Pickard CJ, Brazhkin VV. Speed of sound from fundamental physical constants. Sci Adv 2020; 6:6/41/eabc8662. [PMID: 33036979 PMCID: PMC7546695 DOI: 10.1126/sciadv.abc8662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/27/2020] [Indexed: 05/25/2023]
Abstract
Two dimensionless fundamental physical constants, the fine structure constant α and the proton-to-electron mass ratio [Formula: see text], are attributed a particular importance from the point of view of nuclear synthesis, formation of heavy elements, planets, and life-supporting structures. Here, we show that a combination of these two constants results in a new dimensionless constant that provides the upper bound for the speed of sound in condensed phases, vu We find that [Formula: see text], where c is the speed of light in vacuum. We support this result by a large set of experimental data and first-principles computations for atomic hydrogen. Our result expands the current understanding of how fundamental constants can impose new bounds on important physical properties.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
| | - B Monserrat
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - C J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia.
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7
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Cockrell C, Dicks OA, Brazhkin VV, Trachenko K. Pronounced structural crossover in water at supercritical pressures. J Phys Condens Matter 2020; 32:385102. [PMID: 32434172 DOI: 10.1088/1361-648x/ab94f1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
There have been ample studies of the many phases of H2O in both its solid and low pressure liquid states, and the transitions between them. Using molecular dynamics simulations we address the hitherto unexplored deeply supercritical pressures, where no qualitative transitions are thought to take place and where all properties are expected to vary smoothly. On the basis of these simulations we predict that water at supercritical pressures undergoes a structural crossover across the Frenkel line at pressures as high as 45 times the critical pressure. This provides a new insight into the water phase diagram and establishes a link between the structural and dynamical properties of supercritical water. Specifically, the crossover is demonstrated by a sharp and pronounced at low pressures, and smooth at high pressures, signified by changes in the pair distribution functions and local coordination which coincide with the dynamical transition (the loss of all oscillatory molecular motion) at the Frenkel line on the phase diagram.
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Affiliation(s)
- C Cockrell
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
| | - O A Dicks
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
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8
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Brazhkin VV, Suslov IM. Mechanism of universal conductance fluctuations. J Phys Condens Matter 2020; 32:35LT02. [PMID: 32353837 DOI: 10.1088/1361-648x/ab8ec5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/30/2020] [Indexed: 06/11/2023]
Abstract
Universal conductance fluctuations are usually observed in the form of aperiodic oscillations in the magnetoresistance of thin wires as a function of the magnetic fieldB. If such oscillations are completely random at scales exceedingξB, their Fourier analysis should reveal a white noise spectrum at frequencies belowξB-1. Comparison with the results for 1D systems suggests another scenario: according to it, such oscillations are due to the superposition of incommensurate harmonics and their spectrum should contain discrete frequencies. An accurate Fourier analysis of the classical experiment by Washburn and Webb reveals a purely discrete spectrum in agreement with the latter scenario. However, this spectrum is close in shape to the discrete white noise spectrum whose properties are similar to a continuous one.
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Affiliation(s)
- V V Brazhkin
- Institute for High Pressure Physics, 108840 Troitsk, Moscow, Russia
- P L Kapitza Institute for Physical Problems, 119334 Moscow, Russia
| | - I M Suslov
- Institute for High Pressure Physics, 108840 Troitsk, Moscow, Russia
- P L Kapitza Institute for Physical Problems, 119334 Moscow, Russia
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9
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Dzhavadov LN, Brazhkin VV, Fomin YD, Ryzhov VN, Tsiok EN. Experimental study of water thermodynamics up to 1.2 GPa and 473 K. J Chem Phys 2020; 152:154501. [DOI: 10.1063/5.0002720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- L. N. Dzhavadov
- Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, 108840 Kaluzhskoe shosse, 14, Troitsk, Moscow, Russia
| | - V. V. Brazhkin
- Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, 108840 Kaluzhskoe shosse, 14, Troitsk, Moscow, Russia
| | - Yu. D. Fomin
- Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, 108840 Kaluzhskoe shosse, 14, Troitsk, Moscow, Russia
- Moscow Institute of Physics and Technology, 9 Institutskiy Lane, Dolgoprudny City, Moscow Region, Russia
| | - V. N. Ryzhov
- Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, 108840 Kaluzhskoe shosse, 14, Troitsk, Moscow, Russia
| | - E. N. Tsiok
- Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, 108840 Kaluzhskoe shosse, 14, Troitsk, Moscow, Russia
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10
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Trachenko K, Brazhkin VV. Minimal quantum viscosity from fundamental physical constants. Sci Adv 2020; 6:eaba3747. [PMID: 32426470 PMCID: PMC7182420 DOI: 10.1126/sciadv.aba3747] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 01/30/2020] [Indexed: 05/31/2023]
Abstract
Viscosity of fluids is strongly system dependent, varies across many orders of magnitude, and depends on molecular interactions and structure in a complex way not amenable to first-principles theories. Despite the variations and theoretical difficulties, we find a new quantity setting the minimal kinematic viscosity of fluids: ν m = 1 4 π ℏ m e m , where me and m are electron and molecule masses. We subsequently introduce a new property, the "elementary" viscosity ι with the lower bound set by fundamental physical constants and notably involving the proton-to-electron mass ratio: ι m = ℏ 4 π ( m p m e ) 1 2 , where mp is the proton mass. We discuss the connection of our result to the bound found by Kovtun, Son, and Starinets in strongly interacting field theories.
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Affiliation(s)
- K. Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - V. V. Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
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11
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Wang L, Yang C, Dove MT, Brazhkin VV, Trachenko K. Thermodynamic heterogeneity and crossover in the supercritical state of matter. J Phys Condens Matter 2019; 31:225401. [PMID: 30808013 DOI: 10.1088/1361-648x/ab0ab1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A hallmark of a thermodynamic phase transition is the qualitative change of system thermodynamic properties such as energy and heat capacity. On the other hand, no phase transition is thought to operate in the supercritical state of matter and, for this reason, it was believed that supercritical thermodynamic properties vary smoothly and without any qualitative changes. Here, we perform extensive molecular dynamics simulations in a wide temperature range and find that a deeply supercritical state is thermodynamically heterogeneous, as witnessed by different temperature dependence of energy, heat capacity and its derivatives at low and high temperature. The evidence comes from three different methods of analysis, two of which are model-independent. We propose a new definition of the relative width of the thermodynamic crossover and calculate it to be in the fairly narrow relative range of 13%-20%. On the basis of our results, we relate the crossover to the supercritical Frenkel line.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom
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12
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Gromnitskaya EL, Danilov IV, Lyapin AG, Brazhkin VV. Elastic properties of liquid and glassy propane-based alcohols under high pressure: the increasing role of hydrogen bonds in a homologous family. Phys Chem Chem Phys 2019; 21:2665-2672. [PMID: 30657511 DOI: 10.1039/c8cp07588c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have measured the elastic moduli of liquid and glassy n-propanol and propylene glycol (PG) under pressure by ultrasonic techniques and have recalculated similar characteristics for glycerol from the previous experiment. All three substances form a ternary homologous family with the common formula C3H8-n(OH)n (n = 1, 2, 3), where the number of hydrogen bonds per molecule increases with the number of oxygen atoms approximately as ≈2n. In turn, the enhancement of hydrogen bonding results in an increase in elastic moduli (bulk modulus for liquids or bulk and shear moduli for glasses) from n-propanol to glycerol at all pressures, while the volume per molecule Vm shows the opposite trend at atmospheric pressure in spite of an increase in the molecular size. Nevertheless, the ratios between the Vm values at pressure P > 0.05 GPa are inverted in liquids and tend to the ratios of molecule volumes which indicates a decrease of the relative contribution of hydrogen bonds to the repulsive intermolecular forces with increasing pressure regardless of increase or decrease in the number of hydrogen bonds and their strength. A similar volume behavior is observed for glasses at T = 77 K. We have also established that the relative difference between corresponding moduli of liquid or glassy n-propanol and PG is remarkably less than that between corresponding values for PG and glycerol. We explain this property by the formation of a three-dimensional network of hydrogen bonds in glycerol, where the number of hydrogen bonds per molecule is close to six.
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Affiliation(s)
- E L Gromnitskaya
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow, 108840, Russia.
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13
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Wang L, Yang C, Dove MT, Mokshin AV, Brazhkin VV, Trachenko K. The nature of collective excitations and their crossover at extreme supercritical conditions. Sci Rep 2019; 9:755. [PMID: 30679686 PMCID: PMC6346117 DOI: 10.1038/s41598-018-36178-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/14/2018] [Indexed: 11/09/2022] Open
Abstract
Physical properties of an interacting system are governed by collective excitations, but their nature at extreme supercritical conditions is unknown. Here, we present direct evidence for propagating solid-like longitudinal phonon-like excitations with wavelengths extending to interatomic separations deep in the supercritical state at temperatures up to 3,300 times the critical temperature. We observe that the crossover of dispersion curves develops at k points reducing with temperature. We interpret this effect as the crossover from the collective phonon to the collisional mean-free path regime of particle dynamics and find that the crossover points are close to both the inverse of the shortest available wavelength in the system and to the particle mean free path inferred from experiments and theory. Notably, both the shortest wavelength and mean free path scale with temperature with the same power law, lending further support to our findings.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
| | - C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.,Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - A V Mokshin
- Landau Institute for Theoretical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Russia.,Institute of Physics, Kazan Federal University, 420008, Kazan, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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14
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Kondrin MV, Pronin AA, Brazhkin VV. Secondary Relaxation in Supercooled Liquid Propylene Glycol under Ultrahigh Pressures Revealed by Dielectric Spectroscopy Measurements. J Phys Chem B 2018; 122:9032-9037. [PMID: 30179499 DOI: 10.1021/acs.jpcb.8b07328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,2-Propanediol (propylene glycol) is a well-known glassformer, which easily vitrifies under wide range of cooling rates. An interesting feature of propylene glycol is that, similar to glycerol, it retains one-mode primary relaxation (slow α process) under a wide range of external P- T conditions. It was demonstrated that the emergence of secondary (β) relaxation requires the application of very high pressures P > 4.5 GPa. In this pressure range, the observation of secondary relaxation is partially obfuscated by the presence of strong decoupling of the static (ionic) conductivity and primary relaxation (the fractional Debye-Stokes-Einstein effect). However, secondary relaxation can be unambiguously extracted from experimental data by the correlation procedure of the imaginary and real parts of the dielectric response by means of Cole-Cole plots. This is the second (after glycerol) example of observation of Johari-Goldstein relaxation under ultrahigh pressures P > 2 GPa.
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Affiliation(s)
- M V Kondrin
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk , Moscow 108840 , Russia
| | - A A Pronin
- General Physics Institute , Russian Academy of Sciences , Moscow 117942 , Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk , Moscow 108840 , Russia
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15
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Affiliation(s)
- C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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16
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Brazhkin VV, Prescher C, Fomin YD, Tsiok EN, Lyapin AG, Ryzhov VN, Prakapenka VB, Stefanski J, Trachenko K, Sapelkin A. Comment on “Behavior of Supercritical Fluids across the ‘Frenkel Line’”. J Phys Chem B 2018; 122:6124-6128. [DOI: 10.1021/acs.jpcb.7b11359] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. V. Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - C. Prescher
- Institut für Geologie und Mineralogie, Universität zu Köln, Cologne 50939, Germany
| | - Yu. D. Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - E. N. Tsiok
- Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - A. G. Lyapin
- Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - V. N. Ryzhov
- Institute for High Pressure Physics, Russian Academy of Sciences, 108840 Troitsk, Moscow, Russia
| | - V. B. Prakapenka
- Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - J. Stefanski
- Institut für Geologie und Mineralogie, Universität zu Köln, Cologne 50939, Germany
| | - K. Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - A. Sapelkin
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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17
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Fomin YD, Ryzhov VN, Tsiok EN, Proctor JE, Prescher C, Prakapenka VB, Trachenko K, Brazhkin VV. Dynamics, thermodynamics and structure of liquids and supercritical fluids: crossover at the Frenkel line. J Phys Condens Matter 2018; 30:134003. [PMID: 29443011 DOI: 10.1088/1361-648x/aaaf39] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We review recent work aimed at understanding dynamical and thermodynamic properties of liquids and supercritical fluids. The focus of our discussion is on solid-like transverse collective modes, whose evolution in the supercritical fluids enables one to discuss the main properties of the Frenkel line separating rigid liquid-like and non-rigid gas-like supercritical states. We subsequently present recent experimental evidence of the Frenkel line showing that structural and dynamical crossovers are seen at a pressure and temperature corresponding to the line as predicted by theory and modelling. Finally, we link dynamical and thermodynamic properties of liquids and supercritical fluids by the new calculation of liquid energy governed by the evolution of solid-like transverse modes. The disappearance of those modes at high temperature results in the observed decrease of heat capacity.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 108840, Moscow, Russia
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18
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Wang L, Dove MT, Trachenko K, Fomin YD, Brazhkin VV. Supercritical Grüneisen parameter and its universality at the Frenkel line. Phys Rev E 2018; 96:012107. [PMID: 29347198 DOI: 10.1103/physreve.96.012107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Indexed: 11/07/2022]
Abstract
We study the thermomechanical properties of matter under extreme conditions deep in the supercritical state, at temperatures exceeding the critical one by up to four orders of magnitude. We calculate the Grüneisen parameter γ and find that on isochores it decreases with temperature from 3 to 1, depending on the density. Our results indicate that from the perspective of thermomechanical properties, the supercritical state is characterized by a wide range of γ's which includes solidlike values-an interesting finding in view of the common perception of the supercritical state as being an intermediate state between gases and liquids. We rationalize this result by considering the relative weights of oscillatory and diffusive components of the supercritical system below the Frenkel line. We also find that γ is nearly constant at the Frenkel line above the critical point and explain this universality in terms of the pressure and temperature scaling of system properties along the lines where particle dynamics changes qualitatively.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 108840, Moscow, Russia and Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 108840, Moscow, Russia
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19
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Brazhkin VV, Nikolaev NA, Shulga YM, Lebed YB, Kondrin MV. The structure and synthesis of organic crystalline polymers: hints from ab initio computation. CrystEngComm 2018. [DOI: 10.1039/c8ce00595h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The optical properties and structures of extended covalently bonded hydrocarbon polymers were studied by the DFT method and compared with experimental data.
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Affiliation(s)
| | | | - Y. M. Shulga
- National University of Science and Technology ’MISIS’
- 119049 Moscow
- Russia
| | - Y. B. Lebed
- Institute for Nuclear Research RAS
- Moscow
- Russia
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20
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Smith D, Hakeem MA, Parisiades P, Maynard-Casely HE, Foster D, Eden D, Bull DJ, Marshall ARL, Adawi AM, Howie R, Sapelkin A, Brazhkin VV, Proctor JE. Crossover between liquidlike and gaslike behavior in CH_{4} at 400 K. Phys Rev E 2017; 96:052113. [PMID: 29347717 DOI: 10.1103/physreve.96.052113] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 06/07/2023]
Abstract
We report experimental evidence for a crossover between a liquidlike state and a gaslike state in fluid methane (CH_{4}). This crossover is observed in all of our experiments, up to a temperature of 397 K, 2.1 times the critical temperature of methane. The crossover has been characterized with both Raman spectroscopy and x-ray diffraction in a number of separate experiments, and confirmed to be reversible. We associate this crossover with the Frenkel line-a recently hypothesized crossover in dynamic properties of fluids extending to arbitrarily high pressure and temperature, dividing the phase diagram into separate regions where the fluid possesses liquidlike and gaslike properties. On the liquidlike side the Raman-active vibration increases in frequency linearly as pressure is increased, as expected due to the repulsive interaction between adjacent molecules. On the gaslike side this competes with the attractive van der Waals potential leading the vibration frequency to decrease as pressure is increased.
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Affiliation(s)
- D Smith
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - M A Hakeem
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
| | - P Parisiades
- European Synchrotron Radiation Facility, Beamline ID27, Boîte Postale 220, Grenoble, France
- IMPMC, Université Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France
| | - H E Maynard-Casely
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales, 2232, Australia
| | - D Foster
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
| | - D Eden
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
| | - D J Bull
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
| | - A R L Marshall
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - A M Adawi
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - R Howie
- SUPA, School of Physics and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
- Center for High Pressure Science & Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China
| | - A Sapelkin
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108440 Troitsk, Moscow, Russia
| | - J E Proctor
- Materials and Physics Research Group, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
- Photon Science Institute and School of Electrical and Electronic Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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21
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Danilov IV, Pronin AA, Gromnitskaya EL, Kondrin MV, Lyapin AG, Brazhkin VV. Structural and Dielectric Relaxations in Vitreous and Liquid State of Monohydroxy Alcohol at High Pressure. J Phys Chem B 2017; 121:8203-8210. [PMID: 28766946 DOI: 10.1021/acs.jpcb.7b05335] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-Ethyl-1-hexanol monoalcohol is a well-known molecular glassformer, which for a long time attracts attention of researchers. As in all other monohydroxy alcohols, its dielectric relaxation reveals two distinct relaxation processes attributed to the structural relaxation and another more intense process, which gives rise to a low-frequency Debye-like relaxation. In this monoalcohol, the frequency separation between these two processes reaches an extremely high value of 3 orders of magnitude, which makes this substance a rather convenient object for studies of mechanisms (supposedly common to all monoalcohols) leading to vitrification of this type of liquids. In this work, we apply two experimental techniques, dielectric spectroscopy and ultrasonic measurements (in both longitudinal and transverse polarizations) at high pressure, to study interference between different relaxation mechanisms occurring in this liquid, which could shed light on both structural and dielectric relaxation processes observed in a supercooled liquid and a glass state. Application of high pressure in this case leads to the simplification of the frequency spectrum of dielectric relaxation, where only one asymmetric feature is observed. Nonetheless, the maximum attenuation of the longitudinal wave in ultrasonic experiments at high pressure is observed at temperatures ≈50 K above the corresponding temperature for the transverse wave. This might indicate different mechanisms of structural relaxation in shear and bulk elasticities in this liquid.
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Affiliation(s)
- I V Danilov
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk, Moscow 108840, Russia.,Moscow Institute of Physics and Technology , Dolgoprudny, Moscow Region 141701, Russia
| | - A A Pronin
- General Physics Institute, Russian Academy of Sciences , Moscow 117942, Russia
| | - E L Gromnitskaya
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk, Moscow 108840, Russia
| | - M V Kondrin
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk, Moscow 108840, Russia
| | - A G Lyapin
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk, Moscow 108840, Russia.,Moscow Institute of Physics and Technology , Dolgoprudny, Moscow Region 141701, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences , Troitsk, Moscow 108840, Russia
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22
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Abstract
Investigation of excitation spectra of liquids is one of the hot test topics nowadays. In particular, recent experimental works showed that liquid metals can demonstrate transverse excitations and positive sound dispersion. However, the theoretical description of these experimental observations is still missing. Here we report a molecular dynamics study of excitation spectra of liquid iron. We compare the results with available experimental data to justify the method. After that we perform calculations for high temperatures to find the location of the Frenkel line introduced in our previous works.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, Moscow, 108840, Russia
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23
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Yang C, Dove MT, Brazhkin VV, Trachenko K. Emergence and Evolution of the k Gap in Spectra of Liquid and Supercritical States. Phys Rev Lett 2017; 118:215502. [PMID: 28598668 DOI: 10.1103/physrevlett.118.215502] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Indexed: 06/07/2023]
Abstract
Fundamental understanding of strongly interacting systems necessarily involves collective modes, but their nature and evolution is not generally understood in dynamically disordered and strongly interacting systems such as liquids and supercritical fluids. We report the results of extensive molecular dynamics simulations and provide direct evidence that liquids develop a gap in a solidlike transverse spectrum in the reciprocal space, with no propagating modes between zero and a threshold value. In addition to the liquid state, this result importantly applies to the supercritical state of matter. We show that the emerging gap increases with the inverse of liquid relaxation time and discuss how the gap affects properties of liquid and supercritical states.
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Affiliation(s)
- C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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24
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Wang L, Yang C, Dove MT, Fomin YD, Brazhkin VV, Trachenko K. Direct links between dynamical, thermodynamic, and structural properties of liquids: Modeling results. Phys Rev E 2017; 95:032116. [PMID: 28415224 DOI: 10.1103/physreve.95.032116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Indexed: 06/07/2023]
Abstract
We develop an approach to liquid thermodynamics based on collective modes. We perform extensive molecular-dynamics simulations of noble, molecular, and metallic liquids, and we provide direct evidence that liquid energy and specific heat are well-described by the temperature dependence of the Frenkel (hopping) frequency. The agreement between predicted and calculated thermodynamic properties is seen in the notably wide range of temperature spanning tens of thousands of Kelvin. The range includes both subcritical liquids and supercritical fluids. We discuss the structural crossover and interrelationships between the structure, dynamics, and thermodynamics of liquids and supercritical fluids.
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Affiliation(s)
- L Wang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Yu D Fomin
- Institute for High Pressure Physics, RAS, 142190 Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 142190 Moscow, Russia
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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25
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Lyapin AG, Gromnitskaya E, Danilov IV, Brazhkin VV. Elastic properties of the hydrogen-bonded liquid and glassy glycerol under high pressure: comparison with propylene carbonate. RSC Adv 2017. [DOI: 10.1039/c7ra06165j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We compare elastic properties of the liquid and glassy glycerol and propylene carbonate as the archetypal molecular glass formers with and without hydrogen bonding.
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Affiliation(s)
- A. G. Lyapin
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
- Moscow Institute of Physics and Technology
| | - E. L. Gromnitskaya
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
| | - I. V. Danilov
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
- Moscow Institute of Physics and Technology
| | - V. V. Brazhkin
- Institute for High Pressure Physics
- Russian Academy of Sciences
- Moscow
- 108840 Russia
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26
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Kondrin MV, Nikolaev NA, Boldyrev KN, Shulga YM, Zibrov IP, Brazhkin VV. Bulk graphanes synthesized from benzene and pyridine. CrystEngComm 2017. [DOI: 10.1039/c6ce02327d] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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27
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Fomin YD, Ryzhov VN, Tsiok EN, Brazhkin VV, Trachenko K. Crossover of collective modes and positive sound dispersion in supercritical state. J Phys Condens Matter 2016; 28:43LT01. [PMID: 27603524 DOI: 10.1088/0953-8984/28/43/43lt01] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Supercritical state has been viewed as an intermediate state between gases and liquids with largely unknown physical properties. Here, we address the important ability of supercritical fluids to sustain collective excitations. We directly study propagating modes on the basis of correlation functions calculated in molecular dynamics simulations and find that the supercritical system sustains propagating solid-like transverse modes below the Frenkel line but not above where there is one longitudinal mode only. Important thermodynamic implications of this finding are discussed. We directly detect positive sound dispersion (PSD) below the Frenkel line where transverse modes are operative and quantitatively explain its magnitude on the basis of transverse and longitudinal velocities. PSD disappears above the Frenkel line which therefore demarcates the supercritical phase diagram into two areas where PSD does and does not operate.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
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28
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Brazhkin VV, Ryzhov VN. Erratum: "Van der Waals supercritical fluid: Exact formulas for special lines" [J. Chem. Phys. 135, 084503 (2011)]. J Chem Phys 2016; 145:059901. [PMID: 27497581 DOI: 10.1063/1.4960613] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow Region 142190, Russia and Moscow Institute of Physics and Technology, Moscow State University, Dolgoprudny, Moscow Region 141700, Russia
| | - V N Ryzhov
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow Region 142190, Russia and Moscow Institute of Physics and Technology, Moscow State University, Dolgoprudny, Moscow Region 141700, Russia
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29
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Abstract
We show that the vacuum (zero-point) energy of a low-temperature quantum liquid is a variable property which changes with the state of the system, in notable contrast to the static vacuum energy in solids commonly considered. We further show that this energy is inherently anomalous: it decreases with temperature and gives a negative contribution to a system's heat capacity. This effect operates in an equilibrium and macroscopic system, in marked contrast to small or out-of-equilibrium configurations discussed previously. We find that the negative contribution is over-compensated by the positive term from the excitation of longitudinal fluctuations and demonstrate how the overall positive heat capacity is related to the stability of a condensed phase at the microscopic level.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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30
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Brazhkin VV, Bychkov E, Tsiok OB. Direct Volumetric Study of High-Pressure Driven Polyamorphism and Relaxation in the Glassy Germanium Chalcogenides. J Phys Chem B 2016; 120:358-63. [PMID: 26714214 DOI: 10.1021/acs.jpcb.5b10559] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High precision measurements were taken of the specific volume of glassy germanium chalcogenides GeSe2, GeS2, Ge17Se83, and Ge8Se92 under hydrostatic pressure to 8.5 GPa. For GeSe2 and GeS2 glasses in the pressure range to 3 GPa the behavior is an elastic one with bulk modulus softening at pressures above 2 GPa. At higher pressures the relaxation processes begin that have logarithmic kinetics. The relaxation rate for GeSe2 glasses has a clearly pronounced maximum at 3.5-4.5 GPa, which is indicative of the existence of several mechanisms of structural transformations. For nonstoichiometric glasses inelastic behavior is observed at pressures above 1-1.5 GPa, the relaxation rate being much less than that for stoichiometric ones. For all the glasses we observe the "loss of memory" about the prehistory: A pressure rising after relaxation causes the return of values of the specific volume to the curve of compression without relaxation. After depressurization the residual densification makes up nearly 7% in stoichiometric glasses and 1.5% in Ge17Se83 glasses. The values of the effective bulk modulus for nonstoichiometric glasses coincide upon pressure lowering with the values after isobaric relaxations during pressure increase, whereas for GeSe2 the moduli during the decompression exceed substantially the values after isobaric relaxations at compression path. The results obtained demonstrate high capacity of the volumetric measurements to reveal the nature of the transformations in glassy germanium chalcogenides under compression.
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Affiliation(s)
- V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences , 142190 Troitsk, Moscow, Russia
| | - E Bychkov
- LPCA, UMR 8101 CNRS, Universite du Littoral , 59140 Dunkerque, France
| | - O B Tsiok
- Institute for High Pressure Physics, Russian Academy of Sciences , 142190 Troitsk, Moscow, Russia
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31
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Abstract
Strongly interacting, dynamically disordered and with no small parameter, liquids took a theoretical status between gases and solids with the historical tradition of hydrodynamic description as the starting point. We review different approaches to liquids as well as recent experimental and theoretical work, and propose that liquids do not need classifying in terms of their proximity to gases and solids or any categorizing for that matter. Instead, they are a unique system in their own class with a notably mixed dynamical state in contrast to pure dynamical states of solids and gases. We start with explaining how the first-principles approach to liquids is an intractable, exponentially complex problem of coupled non-linear oscillators with bifurcations. This is followed by a reduction of the problem based on liquid relaxation time τ representing non-perturbative treatment of strong interactions. On the basis of τ, solid-like high-frequency modes are predicted and we review related recent experiments. We demonstrate how the propagation of these modes can be derived by generalizing either hydrodynamic or elasticity equations. We comment on the historical trend to approach liquids using hydrodynamics and compare it to an alternative solid-like approach. We subsequently discuss how collective modes evolve with temperature and how this evolution affects liquid energy and heat capacity as well as other properties such as fast sound. Here, our emphasis is on understanding experimental data in real, rather than model, liquids. Highlighting the dominant role of solid-like high-frequency modes for liquid energy and heat capacity, we review a wide range of liquids: subcritical low-viscous liquids, supercritical state with two different dynamical and thermodynamic regimes separated by the Frenkel line, highly-viscous liquids in the glass transformation range and liquid-glass transition. We subsequently discuss the fairly recent area of liquid-liquid phase transitions, the area where the solid-like properties of liquids have become further apparent. We then discuss gas-like and solid-like approaches to quantum liquids and theoretical issues that are similar to the classical case. Finally, we summarize the emergent view of liquids as a unique system with a mixed dynamical state, and list several areas where interesting insights may appear and continue the extraordinary liquid story.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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32
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Abstract
We consider the correlation between static conductivity and dynamic dielectric relaxation in a number of polar organic liquids. Experimental evidence suggests that in the simple cases the linear dependence between characteristic frequency of relaxation process and the value of static susceptibility is observed. However, this proportionality can be broken due to the appearance of additional relaxation processes (secondary or high-frequency ones) so it can be confused with the "fractional" variant of Debye-Stokes-Einstein relation.
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Affiliation(s)
- M V Kondrin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
| | - Y B Lebed
- Institute for Nuclear Research RAS, 142190 Troitsk, Moscow, Russia
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33
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Trachenko K, Brazhkin VV. Reply to "Comment on 'Dynamic transition of supercritical hydrogen: Defining the boundary between interior and atmosphere in gas giants' ". Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:036102. [PMID: 25871254 DOI: 10.1103/physreve.91.036102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Indexed: 06/04/2023]
Abstract
We have recently proposed the dynamic transition of molecular hydrogen in gas giants around 10 GPa based on the recent understanding of a supercritical state related to the Frenkel line. In the preceding Comment, Bryk makes several remarks with regard to the Frenkel line and its relationship to the speed of sound. We disagree with this discussion and respond to it in this Reply.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 142190 Troitsk, Moscow, Russia
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34
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Fomin YD, Ryzhov VN, Tsiok EN, Brazhkin VV. Thermodynamic properties of supercritical carbon dioxide: Widom and Frenkel lines. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:022111. [PMID: 25768462 DOI: 10.1103/physreve.91.022111] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 06/04/2023]
Abstract
Supercritical fluids are widely used in a number of important technological applications, yet the theoretical progress in the field has been rather moderate. Fairly recently, a new understanding of the liquidlike and gaslike properties of supercritical fluids has come to the fore, particularly with the advent of the Widom and Frenkel lines that aim to demarcate different physical properties on the phase diagram. Here, we report the results of a computational study of supercritical carbon dioxide, one of the most important fluids in the chemical industry. We study the response functions of CO_{2} in the supercritical state and calculate the locations of their maxima (Widom lines). We also report the preliminary calculations of the Frenkel line, the line of crossover of microscopic dynamics of particles. Our insights are relevant to physical processes in the atmosphere of Venus and its evolution.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia and Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - V N Ryzhov
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia and Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - E N Tsiok
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
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35
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Brazhkin VV, Lyapin AG, Ryzhov VN, Trachenko K, Fomin YD, Tsiok EN. The Frenkel line and supercritical technologies. Russ J Phys Chem B 2015. [DOI: 10.1134/s199079311408003x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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36
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Yang C, Brazhkin VV, Dove MT, Trachenko K. Frenkel line and solubility maximum in supercritical fluids. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:012112. [PMID: 25679575 DOI: 10.1103/physreve.91.012112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Indexed: 06/04/2023]
Abstract
A new dynamic line, the Frenkel line, has recently been proposed to separate the supercritical state into rigid-liquid and nonrigid gaslike fluid. The location of the Frenkel line on the phase diagram is unknown for real fluids. Here we map the Frenkel line for three important systems: CO(2), H(2)O, and CH(4). This provides an important demarcation on the phase diagram of these systems, the demarcation that separates two distinct physical states with liquidlike and gaslike properties. We find that the Frenkel line can have a similar trend as the melting line above the critical pressure. Moreover, we discuss the relationship between unexplained solubility maxima and Frenkel line, and we propose that the Frenkel line corresponds to the optimal conditions for solubility.
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Affiliation(s)
- C Yang
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 142190 Moscow, Russia
| | - M T Dove
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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37
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Abstract
Recent advance in understanding the supercritical state posits the existence of a new line above the critical point separating two physically distinct states of matter: rigid liquid and non-rigid gas-like fluid. The location of this line, the Frenkel line, remains unknown for important real systems. Here, we map the Frenkel line on the phase diagram of supercritical iron using molecular dynamics simulations. On the basis of our data, we propose a general recipe to locate the Frenkel line for any system, the recipe that importantly does not involve system-specific detailed calculations and relies on the knowledge of the melting line only. We further discuss the relationship between the Frenkel line and the metal-insulator transition in supercritical liquid metals. Our results enable predicting the state of supercritical iron in several conditions of interest. In particular, we predict that liquid iron in the Jupiter core is in the "rigid liquid" state and is highly conducting. We finally analyse the evolution of iron conductivity in the core of smaller planets such as Earth and Venus as well as exoplanets: as planets cool off, the supercritical core undergoes the transition to the rigid-liquid conducting state at the Frenkel line.
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Affiliation(s)
- Yu. D. Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - V. N. Ryzhov
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - E. N. Tsiok
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
| | - V. V. Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
| | - K. Trachenko
- School of Physics and Astronomy Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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38
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Abstract
We present the high pressure (up to 3 GPa) dielectric spectroscopy study of ethanol in supercooled liquid and solid states. It was found that ethanol can be obtained in the glassy form by relatively slow cooling in the pressure range below 1.5 GPa. Glassy dynamics of ethanol is dominated by hydrogen bonds which cause rise of fragility index with pressure rising and relatively slow increase of glassification temperature. The termination of ethanol galssification at 1.5 GPa is related to the phase transition of ethanol in this pressure range to the disordered crystal structure which allows easy crystallization of ethanol at high pressures. Dielectric spectroscopy of solid phases of ethanol reveals the presence of molecular motion in both of them in the temperature range close to the melting curve but demonstrates different molecular dynamics in the two solid phases of ethanol.
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Affiliation(s)
- M V Kondrin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
| | - A A Pronin
- General Physics Institute RAS, 117942 Moscow, Russia
| | - V V Brazhkin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
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39
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Brazhkin VV, Trachenko K. Collective Excitations and Thermodynamics of Disordered State: New Insights into an Old Problem. J Phys Chem B 2014; 118:11417-27. [DOI: 10.1021/jp503647s] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. V. Brazhkin
- Institute
for High Pressure Physics, RAS, 142190, Moscow, Russia
| | - K. Trachenko
- School
of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, U.K
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Brazhkin VV, Fomin YD, Ryzhov VN, Tareyeva EE, Tsiok EN. True Widom line for a square-well system. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:042136. [PMID: 24827221 DOI: 10.1103/physreve.89.042136] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Indexed: 06/03/2023]
Abstract
In the present paper we propose a van der Waals-like model that allows a purely analytical study of fluid properties including the equation of state, phase behavior, and supercritical fluctuations. We take a square-well system as an example and calculate its liquid-gas transition line and supercritical fluctuations. Employing this model allows us to calculate not only the thermodynamic response functions (isothermal compressibility βT, isobaric heat capacity CP, density fluctuations ζT, and thermal expansion coefficient αT), but also the correlation length in the fluid ξ. It is shown that the bunch of extrema widens rapidly upon departure from the critical point. It seems that the Widom line defined in this way cannot be considered as a real boundary that divides the supercritical region into gaslike and liquidlike regions. As it has been shown recently, a dynamic line on the phase diagram in the supercritical region, namely, the Frenkel line, can be used for this purpose.
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Affiliation(s)
- V V Brazhkin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
| | - Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
| | - V N Ryzhov
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
| | - E E Tareyeva
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
| | - E N Tsiok
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow Region, Russia
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41
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Trachenko K, Brazhkin VV, Bolmatov D. Dynamic transition of supercritical hydrogen: defining the boundary between interior and atmosphere in gas giants. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:032126. [PMID: 24730809 DOI: 10.1103/physreve.89.032126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Indexed: 06/03/2023]
Abstract
Understanding the physics of gas giants requires knowledge about the behavior of hydrogen at extreme pressures and temperatures. Molecular hydrogen in these planets is supercritical, and has been considered as a physically homogeneous state where no differences can be made between a liquid and a gas and where all properties undergo no marked or distinct changes with pressure and temperature, the picture believed to hold below the dissociation and metallization transition. Here, we show that in Jupiter and Saturn, supercritical molecular hydrogen undergoes a dynamic transition around 10 GPa and 3000 K from the "rigid" liquid state to the "nonrigid" gas-like fluid state at the Frenkel line recently proposed, with the accompanying qualitative changes of all major physical properties. The consequences of this finding are discussed, including a physically justified way to demarcate the interior and the atmosphere in gas giants.
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Affiliation(s)
- K Trachenko
- South East Physics Network and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, Moscow 142190, Russia
| | - D Bolmatov
- South East Physics Network and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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42
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Bolmatov D, Brazhkin VV, Fomin YD, Ryzhov VN, Trachenko K. Evidence for structural crossover in the supercritical state. J Chem Phys 2013; 139:234501. [DOI: 10.1063/1.4844135] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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43
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Brazhkin VV, Fomin YD, Lyapin AG, Ryzhov VN, Tsiok EN, Trachenko K. "Liquid-gas" transition in the supercritical region: fundamental changes in the particle dynamics. Phys Rev Lett 2013; 111:145901. [PMID: 24138256 DOI: 10.1103/physrevlett.111.145901] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Indexed: 06/02/2023]
Abstract
Recently, we have proposed a new dynamic line on the phase diagram in the supercritical region, the Frenkel line. Crossing the line corresponds to the radical changes of system properties. Here, we focus on the dynamics of model Lennard-Jones and soft-sphere fluids. We show that the location of the line can be rigorously and quantitatively established on the basis of the velocity autocorrelation function (VAF) and mean-square displacements. VAF is oscillatory below the line at low temperature, and is monotonically decreasing above the line at high temperature. Using this criterion, we show that the crossover of particle dynamics and key liquid properties occur on the same line. We also show that positive sound dispersion disappears in the vicinity of the line in both systems. We further demonstrate that the dynamic line bears no relationship to the existence of the critical point. Finally, we find that the region of existence of liquidlike dynamics narrows with the increase of the exponent of the repulsive part of interatomic potential.
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Affiliation(s)
- V V Brazhkin
- Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow, Russia
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44
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Kondrin MV, Pronin AA, Lebed YB, Brazhkin VV. Phase transformations in methanol at high pressure measured by dielectric spectroscopy technique. J Chem Phys 2013; 139:084510. [DOI: 10.1063/1.4819330] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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45
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Bolmatov D, Brazhkin VV, Trachenko K. Thermodynamic behaviour of supercritical matter. Nat Commun 2013; 4:2331. [DOI: 10.1038/ncomms3331] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/19/2013] [Indexed: 11/09/2022] Open
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46
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Abstract
We report a molecular dynamics study of the transport coefficients and the infinite frequency shear modulus of liquid iron at high temperatures and high pressures. We observe a simultaneous rise of both the shear viscosity and the diffusion coefficient along the melting line and estimate whether liquid iron can vitrify under Earth-core conditions. We show that in the conditions of the model studied in our work iron demonstrates a moderate increase of viscosity along the melting line. It is also demonstrated that at the limit of high temperatures and high pressures the liquid iron behaves similarly to the soft sphere system with exponent n ≈ 4.6.
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Affiliation(s)
- Yu D Fomin
- Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk 142190, Moscow, Russia.
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47
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Andritsos EI, Zarkadoula E, Phillips AE, Dove MT, Walker CJ, Brazhkin VV, Trachenko K. The heat capacity of matter beyond the Dulong-Petit value. J Phys Condens Matter 2013; 25:235401. [PMID: 23676992 DOI: 10.1088/0953-8984/25/23/235401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We propose a simple new way to evaluate the effect of anharmonicity on a system's thermodynamic functions, such as heat capacity. In this approach, the contribution of all the potentially complicated anharmonic effects to the constant-volume heat capacity is evaluated using one parameter only: the coefficient of thermal expansion. Importantly, this approach is applicable not only to crystals, but also to glasses and viscous liquids. To support this proposal, we perform molecular dynamics simulations of several crystalline and amorphous solids as well as liquids, and find a good agreement between the results from theory and simulations. We observe an interesting non-monotonic behavior of the liquid heat capacity with a maximum, and explain this effect as being a result of competition between anharmonicity at low temperature and decreasing number of transverse modes at high temperature.
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Affiliation(s)
- E I Andritsos
- School of Physics and Astronomy, Queen Mary University of London, London, UK
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48
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Bolotina NB, Brazhkin VV, Dyuzheva TI, Lityagina LM, Kulikova LF, Nikolaev NA, Verin IA. Crystal structure of new AsS2 compound. CRYSTALLOGR REP+ 2013. [DOI: 10.1134/s1063774513010069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Abstract
Liquids flow, and in this sense are close to gases. At the same time, interactions in liquids are strong as in solids. The combination of these two properties is believed to be the ultimate obstacle to constructing a general theory of liquids. Here, we adopt a new approach: instead of focusing on the problem of strong interactions, we zero in on the relative contributions of vibrational and diffusional motion. We show that liquid energy and specific heat are given, to a very good approximation, by their vibrational contributions as in solids over almost entire range of relaxation time in which liquids exist as such, and demonstrate that this result is consistent with liquid entropy exceeding solid entropy. Our analysis therefore reveals an interesting duality of liquids not hitherto known: they are close to solids from the thermodynamic perspective and to flowing gases. We discuss several implications of this result.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
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50
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Kondrin MV, Gromnitskaya EL, Pronin AA, Lyapin AG, Brazhkin VV, Volkov AA. Dielectric spectroscopy and ultrasonic study of propylene carbonate under ultra-high pressures. J Chem Phys 2012; 137:084502. [DOI: 10.1063/1.4746022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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