Multiple Path-Dependent Routes for Phase-Transition Kinetics in Thermoresponsive and Field-Responsive Ultrasoft Colloids

Mohanty, Priti S.; Bagheri, Payam; Nojd, Söfi; Yethiraj, Anand; Schurtenberger, Peter

doi:10.1103/physrevx.5.011030

Cited by 46 publications

(93 citation statements)

References 33 publications

(42 reference statements)

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“…Evidence of bond orientational foreshadowing of crystallization has been suggested for colloidal systems both in simulations [17-19, 44, 54, 111, 123] and experiments [112,113,124]. Interestingly, the role of structural fluctuations has been investigated also in a variety of different systems, like metallic melts [70,125,126], anisotropic particles [127][128][129], and polymers [130,131].…”

Section: Translational Vs Orientational Order Curvesmentioning

confidence: 99%

Crystal nucleation as the ordering of multiple order parameters

Russo

Tanaka

2016

The Journal of Chemical Physics

101

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Nucleation is an activated process in which the system has to overcome a free energy barrier in order for a first-order phase transition between the metastable and the stable phases to take place. In the liquid-to-solid transition the process occurs between phases of different symmetry, and it is thus inherently a multi-dimensional process, in which all symmetries are broken at the transition. In this Focus Article, we consider some recent studies which highlight the multi-dimensional nature of the nucleation process. Even for a single-component system, the formation of solid crystals from the metastable melt involves fluctuations of two (or more) order parameters, often associated with the decoupling of positional and orientational symmetry breaking. In other words, we need at least two order parameters to describe the free-energy of a system including its liquid and crystalline states. This decoupling occurs naturally for asymmetric particles or directional interactions, focusing here on the case of water, but we will show that it also affects spherically symmetric interacting particles, such as the hard-sphere system. We will show how the treatment of nucleation as a multi-dimensional process has shed new light on the process of polymorph selection, on the effect of external fields on the nucleation process, and on glass-forming ability.

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Section: Translational Vs Orientational Order Curvesmentioning

confidence: 99%

Crystal nucleation as the ordering of multiple order parameters

Russo

Tanaka

2016

The Journal of Chemical Physics

101

View full text Add to dashboard Cite

show abstract

“…Evidence of bond orientational foreshadowing of crystallization has been suggested for colloidal systems both in simulations [11,12,31,60,64,73] and experiments [65,66,74]. Interestingly, the role of structural fluctuations has been investigated also in a variety of different systems, like water [75], metallic melts [76,77], anisotropic particles [78][79][80], and polymers [81,82].…”

Section: Two-step Nucleation and Precursorsmentioning

confidence: 99%

Nonclassical pathways of crystallization in colloidal systems

Russo

Tanaka

2016

MRS Bull.

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Colloidal systems offer the ideal conditions to study the nucleation process, both from an experimental viewpoint, due to their relative large size and long time-scales, and from a modeling point of view, due to the tunability of their interactions. Here we review some recent works that study the process of colloidal crystallization from a microscopic perspective. We focus in particular on non-classical pathways to nucleation where the appearance of the solid crystals involves fluctuations of two (or more) order parameters. We interpret the non-classical behavior as a decoupling of positional and orientational symmetry breaking. We then consider how the nucleation pathway determines which polymorph is selected upon nucleation from the melt. Moreover we show how the study of nucleation pathways not only sheds new light on the microscopic mechanism of nucleation, but also provides important information regarding its avoidance, thus suggesting a deep link between crystallization and vitrification.

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“…Anisotropic stress, rapid quenching, and a small system size have been found to promote martensitic transformations [19]. In colloids, martensitic transitions have been observed in small crystalline clusters [20][21][22] or lattices stretched by external fields [18,[23][24][25]. A solid-solid transition involving an activated nucleation process has recently been experimentally observed at the single-particle level for the first time in colloidal thin-film crystals confined between two glass plates [26].…”

mentioning

confidence: 93%

Nonclassical Nucleation in a Solid-Solid Transition of Confined Hard Spheres

Peng

Han

et al. 2015

Phys. Rev. Lett.

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A solid-solid phase transition of colloidal hard spheres confined between two planar hard walls is studied using a combination of molecular dynamics and Monte Carlo simulation. The transition from a solid consisting of five crystalline layers with square symmetry (5□) to a solid consisting of four layers with triangular symmetry (4△) is shown to occur through a nonclassical nucleation mechanism that involves the initial formation of a precritical liquid cluster, within which the cluster of the stable 4△ phase grows. Free-energy calculations show that the transition occurs in one step, crossing a single free-energy barrier, and that the critical nucleus consists of a small 4△ solid cluster wetted by a metastable liquid. In addition, the liquid cluster and the solid cluster are shown to grow at the planar hard walls. We also find that the critical nucleus size increases with supersaturation, which is at odds with classical nucleation theory. The △-solid-like cluster is shown to contain both face-centered-cubic and hexagonal-close-packed ordered particles. The kinetics of phase transitions plays an important role in condensed-matter physics and materials science. In order to gain a better fundamental understanding of how to control self-assembly processes in the fabrication of novel structures, many experimental and simulation studies have been devoted to colloidal systems. Experiments [1-4] and computer simulations [5][6][7] on bulk hard-sphere colloids suggested that the metastable fluid crystallizes and superheated crystals melt via a single-step nucleation process that is well described by classical nucleation theory (CNT) [8]. However, Ostwald's step rule suggests that the kinetic pathway to the most stable state can initially proceed through the nucleation of intermediate, metastable phases [9]. The effect of a nearby metastable state on nucleation and the occurrence of multistep nucleation processes have been studied in the crystallization of a range of systems including colloids [10,11], proteins [12], and patchy particles [13], and in the crystallization of molecular solids from solution [14].In contrast, the kinetic processes of solid-solid phase transitions, which involve complex structural rearrangements [15], have received considerably less attention [16]. Solid-solid transitions usually occur in a martensitic fashion [17,18] involving the concerted, diffusionless motion of the atoms in the unit cell. Anisotropic stress, rapid quenching, and a small system size have been found to promote martensitic transformations [19]. In colloids, martensitic transitions have been observed in small crystalline clusters [20][21][22] or lattices stretched by external fields [18,[23][24][25]. A solid-solid transition involving an activated nucleation process has recently been experimentally observed at the single-particle level for the first time in colloidal thin-film crystals confined between two glass plates [26]. The equilibrium phase diagram of hard spheres confined between two planar hard walls shows an alternati...

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Multiple Path-Dependent Routes for Phase-Transition Kinetics in Thermoresponsive and Field-Responsive Ultrasoft Colloids

Cited by 46 publications

References 33 publications

Crystal nucleation as the ordering of multiple order parameters

Crystal nucleation as the ordering of multiple order parameters

Nonclassical pathways of crystallization in colloidal systems

Nonclassical Nucleation in a Solid-Solid Transition of Confined Hard Spheres

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