A direct measurement of the minimum in the melting curve of 4He

Pair, C. Le; Taconis, K.W.; Ouboter, R. de Bruyn; Das, Punyatoya

doi:10.1016/s0031-8914(63)80232-3

Cited by 62 publications

(4 citation statements)

References 2 publications

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“…[22][23][24][25][26] The volume dependence of the entropy in the hcp + II mixture determines the temperature derivative of the melting pressure and thus, by integration from 0 K, the shape of the P-T equilibrium curve. The entropy data reported here, which have also been the subject of an earlier brief report, 27 are in good agreement with the high-precision strain gauge measurements by Straty and Adams.…”

Section: Low-pressure Low-temperature Phase Diagram Of 4he and Propementioning

confidence: 99%

Thermodynamic properties of4He. II. The bcc phase and theP-T and V-T phase diagrams below 2 K

et al. 1976

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The constant-volume heat capacity of '*He has been measured at molar volumes from 20.45 to 29.71 cma/mole in the temperature range from 0.3 to 4 K. The entropy has been obtained as a function of volume and temperature by extrapolation of the data to 0 K. The P-T equilibrium curves below 2 K were obtained from the volume dependence of the entropy in the two-phase regions. The V-T curves were obtained above 1.25 K by observation of heat capacity discontinuities at the phase boundaries and below 1.25 K from the equilibrium pressure-temperature data and the properties of the pure phases. The minimum in the melting pressure occurs at 0.774 K and is 8.04 • 10-3 atm below the 0 K value. The corresponding maxima in the molar volumes of the solid and liquid were also determined. In the bcc phase (~S/t~V) x and (OCv/t~V) r are everywhere positive. Both the temperature and volume dependence of the heat capacity are similar to those of bcc 3He, in the very limited ranges of volume and temperature in which the phase could be studied. An unexpected rise in heat capacity in the 20 mK interval below the melting temperature was observed.

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Section: Low-pressure Low-temperature Phase Diagram Of 4he and Propementioning

confidence: 99%

Thermodynamic properties of4He. II. The bcc phase and theP-T and V-T phase diagrams below 2 K

et al. 1976

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“…Thus, this phenomenon should be of interest in materials processing applications, such as the formation of amorphous alloys. 27 Both isotopes of helium exhibit inverse melting, 8,9 and published data suggests that the behavior may also occur in isotactic P4MP1. 10 In proteins, the often sharp transition between the biologically active, organized, native state, and the biologically inactive denatured forms provides a suggestive analogy to melting phenomena.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Both helium isotopes 3 He and 4 He at low temperature exhibit intervals of inverse melting. 8,9 In addition, reports have been published indicating that the polymeric substance isotactic poly ͑4methylpentene-1͒, ''P4MP1,'' also exhibits inverse melting. 10 To the best of our knowledge, no general microscopic theory or model has yet been proposed to describe inverse melting in the domain of classical statistical mechanics.…”

Section: Introductionmentioning

confidence: 99%

A statistical mechanical model for inverse melting

Feeney

Debenedetti

Stillinger

2003

The Journal of Chemical Physics

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Inverse melting is the situation in which a liquid freezes when it is heated isobarically. Both helium isotopes exhibit intervals of inverse melting at low temperature, and published data suggests that isotactic poly ͑4-methylpentene-1͒ also displays this unusual phase behavior. Here we propose a statistical mechanical model for inverse melting. It is a decorated modification of the Gaussian core model, in which particles possess a spectrum of thermally activated internal states. Excitation leads to a change in a particle's Gaussian interaction parameters, and this can result in a spatially periodic crystal possessing a higher entropy than the fluid with which it coexists. Numerical solution of the model, using integral equations and the hypernetted chain closure for the fluid phase, and the Einstein model for the solid phases, identifies two types of inverse melting. One mimics the behavior of the helium isotopes, for which the higher-entropy crystal is denser than the liquid. The other corresponds to inverse melting in poly͑4-methylpentene-1͒, where the high-entropy crystal is less dense than the liquid with which it coexists.

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“…Notable examples of materials exhibiting inverse melting are 3 He [4] and 4 He [5,6], for which the liquid is stabilized at low T by quantum mechanical effects, and polymers poly(4-methylpentene-1) [7][8][9][10] and syndiotactic polystyrene [11]. Motivated by He and polymers, Feeney and coworkers devised a model that successfully recovers inverse melting by coupling internal degrees of freedom of a particle with interparticle interactions [12].…”

Section: Introductionmentioning

confidence: 99%

Inverse melting in a two-dimensional off-lattice model

Almudallal

Buldyrev

Saika‐Voivod

2014

The Journal of Chemical Physics

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We carry out computer simulations of a simple, two-dimensional off-lattice model that exhibits inverse melting. The monodisperse system comprises core-softened disks interacting through a repulsive square shoulder located inside an attractive square well. By systematically varying the potential parameters, we increase the pressure range over which the liquid freezes to a crystal upon isobaric heating. The effect is largely controlled by the extent of the shoulder. Despite occurring in two dimensions, the melting transition is first order and to a liquid, rather than to a hexatic or quasicrystal phase. We also provide comment on a commonly employed correlation function used to determine the degree of translational ordering in a system.

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A direct measurement of the minimum in the melting curve of 4He

Cited by 62 publications

References 2 publications

Thermodynamic properties of4He. II. The bcc phase and theP-T and V-T phase diagrams below 2 K

Thermodynamic properties of4He. II. The bcc phase and theP-T and V-T phase diagrams below 2 K

A statistical mechanical model for inverse melting

Inverse melting in a two-dimensional off-lattice model

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