Kinetics of Phase Transitions

Puri, Sanjay

doi:10.1201/9781420008364.ch1

Cited by 73 publications

(219 citation statements)

References 86 publications

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“…This consistency is what requires the approximation step we have taken above, of dropping the restrictions on the sums defining ∆H αγ i j . 60 This is as one would expect in a closed system, where there are no currents crossing boundaries. 53 We defer the derivation of the result dF/dt to Appendix A, which generalizes similar derivations discussed elsewhere in the literature 53 to include the case of direct particle-particle swapping.…”

Section: Kinetic Plg Modelsupporting

confidence: 56%

Phase separation dynamics of polydisperse colloids: a mean-field lattice-gas theory

Castro

Sollich

2017

Phys. Chem. Chem. Phys.

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New insights into phase separation in colloidal suspensions are provided via a new dynamical theory based on the Polydisperse Lattice-Gas model. The model gives a simplified description of polydisperse colloids, incorporating a hard-core repulsion combined with polydispersity in the strength of the attraction between neighbouring particles. Our mean-field equations describe the local concentration evolution for each of an arbitrary number of species, and for an arbitrary overall composition of the system. We focus on the predictions for the dynamics of colloidal gas-liquid phase separation after a quench into the coexistence region. The critical point and the relevant spinodal curves are determined analytically, with the latter depending only on three moments of the overall composition. The results for the early-time spinodal dynamics show qualitative changes as one crosses a 'quenched' spinodal that excludes fractionation and so allows only density fluctuations at fixed composition. This effect occurs for dense systems, in agreement with a conjecture by Warren that, at high density, fractionation should be generically slow because it requires inter-diffusion of particles. We verify this conclusion by showing that the observed qualitative changes disappear when direct particle-particle swaps are allowed in the dynamics. Finally, the rich behaviour beyond the spinodal regime is examined, where we find that the evaporation of gas bubbles with strongly fractionated interfaces causes long-lived composition heterogeneities in the liquid phase; we introduce a two-dimensional density histogram method that allows such effects to be easily visualized for an arbitrary number of particle species.

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Section: Kinetic Plg Modelsupporting

confidence: 56%

Phase separation dynamics of polydisperse colloids: a mean-field lattice-gas theory

Castro

Sollich

2017

Phys. Chem. Chem. Phys.

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“…As we know, in the synthesis of nanostructures by wet chemical process, the nucleation can start in the reaction solution by homogeneous nucleation [21], or on the rough sites at the support surface by heterogeneous nucleation [22]. The heterogeneous nucleation usually needs a lower energy than homogenous nucleation [23], but subjected to the barrier existed and energy provided for nucleation in the system [24]. In GDL carbon paper, the top layer is mainly constructed by carbon nanospheres.…”

Section: Resultsmentioning

confidence: 99%

Temperature-controlled growth of single-crystal Pt nanowire arrays for high performance catalyst electrodes in polymer electrolyte fuel cells

Steinberger‐Wilckens

2015

Applied Catalysis B: Environmental

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a b s t r a c tThe anisotropic structure and unique surface properties of one-dimensional (1D) Pt-nanowire (PtNW) make it a promising new type of electrocatalyst for various catalyst applications, especially for fuel cells. However, due to the critical synthesis process, a finely tuning of the synthesis temperature for precisely controlling the morphology and distribution of PtNWs in catalyst electrodes still remains a grand challenge. In this work, we present the temperature-controlled growth of PtNWs with large-area 16 cm 2 carbon paper piece as a direct support. The relationship between the growth temperature and PtNW behavior is studied by physical characterization, and their catalytic activity is measured towards oxygen reduction reaction (ORR) by testing as the cathode in a hydrogen-air fuel cell. The results show that the growth temperature plays a vital role on the behavior of PtNWs thus influencing their properties. The catalyst electrode with PtNWs grown at 40 • C shows the best power performance. A possible mechanism for the influence of temperature on PtNW growth is suggested. The comparison with the state-of-the-art commercial TKK catalyst also shows a better performance and durability. The understanding gained in our work from PtNW catalyst electrode could aid in the design of other novel nanostructures in practical applications.

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“…These give access to the time-dependent structure factor, S(k, t), and the dynamic scaling assumption was formulated to describe the time and wave-vector dependence of this observable. More subtle features, such as the Porod tails characterising the long wave-vector dependence of S, were also uncovered from this kind of experimental measurement [3,5]. In spite of the success of Fourier-space methods, real-space techniques are better suited to give direct access to the microscopic mechanisms for coarsening and, therefore, a more detailed understanding of these phenomena.…”

Section: Methodsmentioning

confidence: 96%

“…Phase ordering kinetics are modelled with kinetic Ising or Potts models [9]; they are studied numerically with lattice Boltzmann [6,27] and Monte Carlo simulations, and, mostly analytically, with stochastic equations on coarse-grained fields [3,5]. These approaches give access to different aspects of the processes, and which one is easier to deal with analytically depends upon the issue to explore.…”

Section: Modelsmentioning

confidence: 99%

“…This is the case of, e.g., the voter model. I do not intend to write here a complete overview of the theoretical description of pattern formation and coarsening phenomena, as several excellent review articles, e.g., [1][2][3][4][5][6], and textbooks [7][8][9][10] treating these topics already exist, and many technical aspects will be covered in the following articles. I will, instead, start by giving a very short survey of the main features of phase-ordering kinetics referring the reader to already published references and the relevant chapters in this volume for further details.…”

Section: Introductionmentioning

confidence: 99%

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