Phase behavior of Ising mixtures

Fenz, Walter D.; Folk, R.

doi:10.1103/physreve.71.046104

Cited by 6 publications

(1 citation statement)

References 49 publications

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“…Although many studies have examined binary mixtures, relatively few theoretical works exist in which one or both components can form ordered phases. For example, Ising mixtures composed of a ferromagnetic and a nonmagnetic compound have been investigated; in other works, mixtures of dipolar spheres of different dipolar coupling strengths − as well as binary mixtures composed of dipolar and apolar spheres have been considered. ,− Properties of these systems and, in particular, their possibility to phase separate have important repercussions for the stability of colloidal suspensions; the tendency of binary mixtures of nanoparticles and macromolecules to undergo phase separation is relevant for understanding novel and exciting phenomena such as Casimir forces …”

Section: Introductionmentioning

confidence: 99%

Phase Behavior of Magnetic Nanocolloids of Different Sizes Suspended in an Apolar Solvent

2017

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We employ classical density functional theory (DFT) to investigate the phase behavior and composition of binary mixtures; each compound consists of hard spheres of different sizes with superimposed dispersion attraction. In addition to the dispersion attraction, molecules of one component carry an additional three-dimensional magnetic "spin" where the orientation-dependent spin-spin interaction is accounted for by the Heisenberg model. We are treating the excess free energy using a modified mean-field approximation (second virial coefficient) for the orientation-dependent pair correlation function. Depending on the concentration of the magnetic particles, the strength of the spin-spin coupling, and the size ratio of the particles, the model predicts the formation of ordered (polar) phases in addition to the more conventional gas and isotropic liquid phases. Key features of our model are a particle-size dependent shift of the gas-liquid critical point (critical temperature and density) and a change in the width of the phase diagram. In the near-critical region, the latter can be analyzed quantitativly in terms of an effective critical exponent β that may differ from the classical critical exponent [Formula: see text]; the classical value is attained in the immediate vicinity of the critical point as it must. The deviation between β and β can be linked to nontrivial composition effects along the phase boundaries.

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Section: Introductionmentioning

confidence: 99%

Phase Behavior of Magnetic Nanocolloids of Different Sizes Suspended in an Apolar Solvent

2017

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Predicting phase behavior in multicomponent mixtures

Jacobs

Frenkel

2013

The Journal of Chemical Physics

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Mixtures with a large number of components can undergo phase transitions of a hybrid character, with both condensation and demixing contributions. We describe a robust Monte Carlo simulation method for calculating phase coexistence in multicomponent mixtures. We use this approach to study the phase behavior of lattice models of multicomponent mixtures with strongly varying pair interactions. Such a system can be thought of as a simplified model of the cytosol, with both specific and nonspecific interactions. We show that mapping a multicomponent mixture onto an approximately equivalent one-component system yields both upper and lower bounds on the maximum solute volume fraction of a stable, homogeneous phase. By following the minimum excess-free-energy path from the dilute phase free-energy minimum, we predict the difference in composition between the condensed and dilute phases at the boundary of the homogeneous phase. We find that this "direction" of phase separation rarely aligns with the dominant direction of density fluctuations in the dilute phase. We also show that demixing transitions tend to lower the maximum solute volume fraction at which the homogeneous phase is stable. By considering statistical ensembles of mixtures with random interactions, we show that the demixing contribution to phase separation is self-averaging and dependent only on the mean and variance of the distribution of interactions.

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Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

Chen

2009

Commun. Theor. Phys.

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The phase transition of Heisenberg fluid has been investigated with the density functional theory in meanfield approximation (MF). The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density ρ * = ρσ 3 = 0.224 and the reduced temperature T * = kT / = 1.87 (σ is the diameter of Heisenberg hard sphere and is the coupling constant).

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Phase behavior of Ising mixtures

Cited by 6 publications

References 49 publications

Phase Behavior of Magnetic Nanocolloids of Different Sizes Suspended in an Apolar Solvent

Phase Behavior of Magnetic Nanocolloids of Different Sizes Suspended in an Apolar Solvent

Predicting phase behavior in multicomponent mixtures

Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

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