Capillarity theory for the "coexistence" of liquid and solid clusters

Most studies on melting under confinement focus only on the solid and liquid melt phases. Despite of its ubiquity, contributions from the capillary interface (liquid / vapor interface) are often neglected. In this study the melting behavior of small cylindrical aggregates in vapor attached to planar surfaces is analyzed. For the assumed boundary conditions (cylindrical solid with a non wetting top plane and a wettable side wall) solid and the liquid phases can coexist within a certain temperature range. Due to capillary instability, the liquid phase can form either an axisymmetric rouloid morphology or, above a certain threshold liquid volume fraction, a bulge coexisting with a rouloid-like section. The corresponding melting points are different. The analysis explicitly describes the behavior of a real system of small aggregates of long chain alkanes on planar substrates. It also gives qualitative insights into the melting behavior of small aggregates with anisotropic wetting behaviors in general. It reveals in particular how melting points and melting pathways depend on the energetic respectively morphological pathways leading to complete melting.

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“…In the literature this Gibbs-Thomson (GT) approach often appears in a somewhat more general version 4,[8][9][10][11][12]52 :…”

Section: Conclusion and Summarymentioning

confidence: 99%

Morphological Transitions during Melting of Small Cylindrical Aggregates

Jin

Riegler

2016

J. Phys. Chem. C

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“…5 5 One can notice analogy with the second-order transition: the amplitude H plays the role of an OP, (−X)-the temperature, and (−X)-the critical temperature.…”

Section: Heterogeneous Systemsmentioning

confidence: 99%

“…For a melting/freezing-type transition the lowest lying minima correspond to the crystalline phases, the liquid phase corresponds to a certain level of kinetic energy-that is, Lindemann-type criterion-and the amorphous phase corresponds to few shallow minima that separate the absolute-minimum basins of the crystalline phase. Over a certain range of temperature and pressure, clusters may exhibit effects that are not typical for bulk matter: dynamical coexistence-intermittent visitations of two or more different regions of the phase space {r t ,ṙ t } at equilibrium [5,6]; 1 existence of equilibrium phases which are completely unstable in the bulk, e.g. icosahedral [7,8].…”

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confidence: 99%

Thermodynamic Stability of Transition States in Nanosystems

Umantsev

2009

J Stat Phys

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We present a theory which shows that, in a closed system of fixed volume capable of undergoing a phase transition, the transition state can be thermodynamically stable against the bulk phases if a certain material parameters criterion is fulfilled. In a small system below the critical size the transition state turns into a globally stable phase that can be observed experimentally. This effect is analogous to stabilization of icosahedral structures in clusters of certain sizes and energies. Stabilization of the transition state in small systems of limited resources allows us to conjecture that, in the case of a melting/freezing transition in pure substances, this state corresponds to an amorphous phase. Although unstable in open systems, this phase may be observed experimentally due to slow kinetics of its decomposition at low temperatures. The material-parameters criterion should help experimenters select the materials for the experimental verification of the phenomenon. In the present paper we consider thin films where the phase separation is permitted only parallel to the plane of the film. The calculations, however, hold true for 3D small systems: e.g., nanoparticles.

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“…That such ranges exist was demonstrated both in early simulations and in the experiments cited above. However, apart from one early discussion based on a continuum-capillarity model [21], the conditions and constraints that allow the coexistence ranges to be wide enough to be detectable had not been identified until very recently [22,23].…”

Section: Introductionmentioning

confidence: 99%

Entropy and Phase Coexistence in Clusters: Metals vs. Nonmetals

Berry

Smirnov

2010

Entropy

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Small clusters violate the Gibbs phase rule by exhibiting two or more phases in thermodynamic equilibrium over bands of temperature and pressure. The reason is the small number of particles comprising each system. We review recent results concerning the size ranges for which this behavior is observable. The principal characteristic determining the coexistence range is the transitions entropy change. We review how this happens, using simulations of 13-atom Lennard-Jones and metal clusters to compare dielectric clusters with the more complex clusters of metal atoms. The dominating difference between the narrower coexistence bands of dielectrics and the wider bands of metal clusters is the much higher configurational entropy of the liquid metal clusters.

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Capillarity theory for the "coexistence" of liquid and solid clusters

Cited by 195 publications

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Morphological Transitions during Melting of Small Cylindrical Aggregates

Morphological Transitions during Melting of Small Cylindrical Aggregates

Thermodynamic Stability of Transition States in Nanosystems

Entropy and Phase Coexistence in Clusters: Metals vs. Nonmetals

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