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arXiv 1912.09441cond-mat.soft
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不同温度颗粒混合物中的相分离和成核

Phase separation and nucleation in mixtures of particles with different temperatures

Efe Ilker, Jean-François Joanny

摘要:

胶体颗粒中活性的差异足以驱动活性和无源(或活性较低)颗粒之间的相分离,即使它们仅排除体积相互作用。本文研究了胶体混合物的相分离动力学,提出了扩散极限下的相分离理论。我们的模型考虑了耦合到不同恒温器的扩散粒子的混合物,因此由于温度差异,它具有非平衡性质。然而,我们表明,系统确实恢复了有效的平衡热力学在稀极限。我们得到的相图显示的不对称的浓度,由于活动的差异。通过使用一个更一般的方法,我们证明了相分离动力学与著名的Cahn-Hilliard理论的等价性。另一方面,浓度的高阶展开表明非平衡效应的出现,导致平衡类比的崩溃。我们奠定了一般的理论,我们证明了几个应用程序中的参数。在这个简单的形式主义,我们捕获一个积极的表面张力硬球},和有趣的比例关系的界面特性,液滴生长动力学,和相分离条件。\rev {我们的一些结果与现有的数值模拟一致,同时我们也提出了可检验的预测。

英文摘要:

Differences in activities in colloidal particles are sufficient to drive phase separation between active and passive (or less active) particles, even if they have only excluded volume interactions. In this paper, we study the phase separation kinetics and propose a theory of phase separation of colloidal mixtures in the diffusive limit. Our model considers a mixture of diffusing particles coupled to different thermostats, it thus has a non-equilibrium nature due to the temperature differences. However, we show that indeed the system recovers an effective equilibrium thermodynamics in the dilute limit. We obtain phase diagrams showing the asymmetry in concentrations due to activity differences. By using a more general approach, we show the equivalence of phase separation kinetics with the well known Cahn-Hilliard theory. On the other hand, higher order expansions in concentration indicate the emergence of non-equilibrium effects leading to a breakdown of the equilibrium analogy. We lay out the general theory in terms of accessible parameters which we demonstrate by several applications. In this simple formalism, we capture a positive surface tension for hard spheres}, and interesting scaling laws for interfacial properties, droplet growth dynamics, and phase segregation conditions. \rev{Several of our results are in agreement with existing numerical simulations while we also propose testable predictions.

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