Melting and freezing lines for a mixture of charged colloidal spheres with spindle-type phase diagram

Lorenz, Nina; Palberg, Thomas

doi:10.1063/1.3487523

Cited by 16 publications

(16 citation statements)

References 70 publications

(109 reference statements)

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“…We found, that utilizing Z ef f,G to localize the observed melting line in the effective temperaturecoupling parameter plane of the phase diagram regularly yielded a good agreement of our results with the theoretical predicted location of the melting line [136][137][138][139][140][141][142]. By contrast, no agreement was observed when Z ef f,σ was used [115,119,120,125], i.e. when neglecting many-body effects on the effective charge.…”

Section: Appendix B: Characterization Of Particle Interactions Under supporting

confidence: 63%

“…Here a is the particle radius, λ B = 0.72nm is the Bjerrum length in water and Z ef f,G is the effective charge from elasticity measurements [118]. In the deionized state, all samples including the mixture form polycrystalline bcc solids for n ≥ n F = (2 − 8)µm −3 with the location of the melting line coinciding with theoretical expectations [115,119,120].…”

Section: A Particle Characterizationmentioning

confidence: 60%

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Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres

2016

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The interfacial free energy is a central quantity in crystallization from the metastable melt. In suspensions of charged colloidal spheres, nucleation and growth kinetics can be accurately measured from optical experiments. In previous work, from these data effective nonequilibrium values for the interfacial free energy between the emerging bcc nuclei and the adjacent melt in dependence on the chemical potential difference between melt phase and crystal phase were derived using classical nucleation theory (CNT). A strictly linear increase of the interfacial free energy was observed as a function of increased metastability. Here, we further analyze these data for five aqueous suspensions of charged spheres and one binary mixture. We utilize a simple extrapolation scheme and interpret our findings in view of Turnbull's empirical rule. This enables us to present the first systematic experimental estimates for a reduced interfacial free energy, σ(0,bcc), between the bcc-crystal phase and the coexisting equilibrium fluid. Values obtained for σ(0,bcc) are on the order of a few k(B)T. Their values are not correlated to any of the electrostatic interaction parameters but rather show a systematic decrease with increasing size polydispersity and a lower value for the mixture as compared to the pure components. At the same time, σ(0) also shows an approximately linear correlation to the entropy of freezing. The equilibrium interfacial free energy of strictly monodisperse charged spheres may therefore be still greater.

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Section: Appendix B: Characterization Of Particle Interactions Under supporting

confidence: 63%

Section: A Particle Characterizationmentioning

confidence: 60%

Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres

2016

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“…Within the formalism of CNT the solid-liquid interfacial energy γ determines the surface contribution to the total free energy, i.e., G(r) = 4πr 2 γ + (4/3)πr 3 n μ (12) whereas the undercooling μ acts in a similar way for the volume term. In our case, the undercooling is obtained from a WilsonFrenkel-type plot (not shown; compare …”

Section: Evaluation Of Key Parameters Of Nucleationmentioning

confidence: 99%

Nucleation and crystal growth in a suspension of charged colloidal silica spheres with bi-modal size distribution studied by time-resolved ultra-small-angle X-ray scattering

Hornfeck

Menke

Forthaus

et al. 2014

The Journal of Chemical Physics

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A suspension of charged colloidal silica spheres exhibiting a bi-modal size distribution of particles, thereby mimicking a binary mixture, was studied using time-resolved ultra-small-angle synchrotron X-ray scattering (USAXS). The sample, consisting of particles of diameters d(A) = (104.7 ± 9.0) nm and d(B) = (88.1 ± 7.8) nm (d(A)/d(B) ≈ 1.2), and with an estimated composition A(0.6(1))B(0.4(1)), was studied with respect to its phase behaviour in dependance of particle number density and interaction, of which the latter was modulated by varying amounts of added base (NaOH). Moreover, its short-range order in the fluid state and its eventual solidification into a long-range ordered colloidal crystal were observed in situ, allowing the measurement of the associated kinetics of nucleation and crystal growth. Key parameters of the nucleation kinetics such as crystallinity, crystallite number density, and nucleation rate density were extracted from the time-resolved scattering curves. By this means an estimate on the interfacial energy for the interface between the icosahedral short-range ordered fluid and a body-centered cubic colloidal crystal was obtained, comparable to previously determined values for single-component colloidal systems.

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“…Alternatively, one can study systems of charged colloidal spheres. For example, Lorenz and Palberg observed melting and freezing lines for a binary mixture of colloidal spheres [31].…”

Section: Introductionmentioning

confidence: 99%

Direct molecular dynamics simulation of liquid-solid phase equilibria for two-component plasmas

et al. 2012

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We determine the liquid-solid phase diagram for carbon-oxygen and oxygen-selenium plasma mixtures using two-phase molecular dynamics simulations. We identify liquid, solid, and interface regions using a bond angle metric. To study finite-size effects, we perform 27 648-and 55 296-ion simulations. To help monitor nonequilibrium effects, we calculate diffusion constants D i . For the carbon-oxygen system we find that D O for oxygen ions in the solid is much smaller than D C for carbon ions and that both diffusion constants are 80 or more times smaller than diffusion constants in the liquid phase. There is excellent agreement between our carbon-oxygen phase diagram and that predicted by Medin and Cumming. This suggests that errors from finite-size and nonequilibrium effects are small and that the carbon-oxygen phase diagram is now accurately known. The oxygen-selenium system is a simple two-component model for more complex rapid proton capture nucleosynthesis ash compositions for an accreting neutron star. Diffusion of oxygen, in a predominantly selenium crystal, is remarkably fast, comparable to diffusion in the liquid phase. We find a somewhat lower melting temperature for the oxygen-selenium system than that predicted by Medin and Cumming. This is probably because of electron screening effects.

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Melting and freezing lines for a mixture of charged colloidal spheres with spindle-type phase diagram

Abstract: We have measured the phase behavior of a binary mixture of like-charged colloidal spheres with a size ratio of Γ = 0.9 and a charge ratio of Λ = 0.96 as a function of particle number density n and composition p. Under exhaustively deionized conditions the aqueous suspension

Cited by 16 publications

References 70 publications

Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres

Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres

Nucleation and crystal growth in a suspension of charged colloidal silica spheres with bi-modal size distribution studied by time-resolved ultra-small-angle X-ray scattering

Direct molecular dynamics simulation of liquid-solid phase equilibria for two-component plasmas

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