1
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Shoemaker BA, Domingues TS, Haji-Akbari A. Ideal Conductor Model: An Analytical Finite-Size Correction for Nonequilibrium Molecular Dynamics Simulations of Ion Transport through Nanoporous Membranes. J Chem Theory Comput 2022; 18:7142-7154. [PMID: 36327152 DOI: 10.1021/acs.jctc.2c00375] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Modulating ion transport through nanoporous membranes is critical to many important chemical and biological separation processes. The corresponding transport timescales, however, are often too long to capture accurately using conventional molecular dynamics (MD). Recently, path sampling techniques, such as forward-flux sampling (FFS), have emerged as attractive alternatives for efficiently and accurately estimating arbitrarily long ionic passage times. Here, we use non-equilibrium MD and FFS to explore how the kinetics and mechanisms of pressure-driven chloride transport through a nanoporous graphitic membrane are affected by its lateral dimensions. We not only find ionic passage times and free energy barriers to decrease dramatically upon increasing the membrane surface area but also observe an abrupt and discontinuous change in the locus of the transition state. These strong finite size effects arise due to the cumulative effect of the periodic images of the leading ion entering the pore on the distribution of the induced excess charge at the membrane surface in the feed. By assuming that the feed is an ideal conductor, we analytically derive a finite size correction term that can be computed from the information obtained from a single simulation and successfully use it to obtain corrected free energy profiles with no dependence on the system size. We then estimate ionic passage times in the thermodynamic limit by assuming an Eyring-type dependence of rates on barriers with a size-independent prefactor. This approach constitutes a universal framework for removing finite size artifacts in molecular simulations of ion transport through nanoporous membranes and biological channel proteins.
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Affiliation(s)
- Brian A Shoemaker
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut06520, United States
| | - Tiago S Domingues
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut06520, United States
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut06520, United States
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2
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Yao X, Liu Q, Wang B, Yu J, Aristov MM, Shi C, Zhang GGZ, Yu L. Anisotropic Molecular Organization at a Liquid/Vapor Interface Promotes Crystal Nucleation with Polymorph Selection. J Am Chem Soc 2022; 144:11638-11645. [PMID: 35735940 DOI: 10.1021/jacs.2c02623] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The molecules at the surface of a liquid have different organization and dynamics from those in the bulk, potentially altering the rate of crystal nucleation and polymorphic selection, but this effect remains poorly understood. Here we demonstrate that nucleation at the surface of a pure liquid, d-arabitol, is vastly enhanced, by 12 orders of magnitude, and selects a different polymorph. The surface effect intensifies with cooling and can be inhibited by a dilute, surface-active second component. This phenomenon arises from the anisotropic molecular packing at the interface and its similarity to the surface-nucleating polymorph. Our finding is relevant for controlling the crystallization and polymorphism in any system with a significant interface such as nanodroplets and atmospheric water.
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Affiliation(s)
- Xin Yao
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Qitong Liu
- Civil & Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Bu Wang
- Civil & Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Junguang Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Michael M Aristov
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Chenyang Shi
- Drug Product Development, Research and Development, AbbVie Inc., North Chicago, Illinois 60064, United States
| | - Geoff G Z Zhang
- Drug Product Development, Research and Development, AbbVie Inc., North Chicago, Illinois 60064, United States
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
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3
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Jung C, Ihm Y, Cho DH, Lee H, Nam D, Kim S, Eom IT, Park J, Kim C, Kim Y, Fan J, Ji N, Morris JR, Owada S, Tono K, Shim JH, Jiang H, Yabashi M, Ishikawa T, Noh DY, Song C. Inducing thermodynamically blocked atomic ordering via strongly driven nonequilibrium kinetics. SCIENCE ADVANCES 2021; 7:eabj8552. [PMID: 34936432 PMCID: PMC8694629 DOI: 10.1126/sciadv.abj8552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 11/02/2021] [Indexed: 05/22/2023]
Abstract
Ultrafast light-matter interactions enable inducing exotic material phases by promoting access to kinetic processes blocked in equilibrium. Despite potential opportunities, actively using nonequilibrium kinetics for material discovery is limited by the poor understanding on intermediate states of driven systems. Here, using single-pulse time-resolved imaging with x-ray free-electron lasers, we found intermediate states of photoexcited bismuth nanoparticles that showed kinetically reversed surface ordering during ultrafast melting. This entropy-lowering reaction was further investigated by molecular dynamics simulations to reveal that observed kinetics were thermodynamically buried in equilibrium, which emphasized the critical role of electron-mediated ultrafast free-energy modification in inducing exotic material phases. This study demonstrated that ultrafast photoexcitations of electrons provide an efficient strategy to induce hidden material phases by overcoming thermodynamic barriers via nonequilibrium reaction pathways.
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Affiliation(s)
- Chulho Jung
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Yungok Ihm
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Do Hyung Cho
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Heemin Lee
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Daewoong Nam
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - Sangsoo Kim
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - In-Tae Eom
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - Jaehyun Park
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Chan Kim
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- European XFEL GmbH, Schenefeld 22869, Germany
| | - Yoonhee Kim
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- European XFEL GmbH, Schenefeld 22869, Germany
| | - Jiadong Fan
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - Nianjing Ji
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - James R. Morris
- Materials Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Ames Laboratory, Iowa State University, Ames, IA 50011, USA
| | - Shigeki Owada
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Ji Hoon Shim
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Huaidong Jiang
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - Makina Yabashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | | | - Do Young Noh
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- Institute for Basic Sciences (IBS), Daejeon 34126, Korea
| | - Changyong Song
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Asia Pacific Center for Theoretical Physics, POSTECH, Pohang 37673, Korea
- Corresponding author.
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4
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Guo C, Qin H, Zhu Y, Lü Y. Weakly Anisotropic Dielectric Properties of Water Droplets at the Nanoscale. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13059-13066. [PMID: 34709837 DOI: 10.1021/acs.langmuir.1c02207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The slab-confined water at the nanoscale exhibits anomalous dielectric properties compared to bulk water, for example, significantly low dielectric constant. In this work, we study the dielectric properties of nanoscale water droplets at room temperature using molecular dynamics simulations. We find that the nanoscale water droplets feature weakly anisotropic dielectric constant: the radial component of dielectric constants is distinctly smaller than the tangential component although they both decrease with reducing droplet size in a similar way. Such dielectric behavior is closely related to the orientational preference of water molecules near the convex surface. The molecular dipole prefers to slightly orientate toward the interior of droplets in contrast to the out-of-plane preference for free-standing water films and slab-confined water, which suppresses the fluctuation of dipole moments in the radial direction. Meanwhile, it facilitates the formation of the open hydrogen-bond network in the surface layer and ultimately leads to the relatively weak suppression of tangential fluctuations. The differential suppression is responsible for the anisotropic dielectric constant of water droplets. This anisotropic characteristic is also found in dielectric relaxation: both the radial and the tangential relaxation are consistently slowed down upon approaching surface but the latter is universally slower.
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Affiliation(s)
- Chenchen Guo
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Hairong Qin
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Yong Zhu
- Science and Technology on Electromagnetic Scattering Laboratory, Beijing 100854, P. R. China
| | - Yongjun Lü
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
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5
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Li Y, Peng P, Xu D, Yang R. Identification of critical nuclei in the rapid solidification via configuration heredity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:175701. [PMID: 33508806 DOI: 10.1088/1361-648x/abe0e1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
The identification and characterization of critical nuclei is a long-standing issue in the rapid solidification of metals and alloys. An ambiguous description for their sizes and shapes used to lead to an overestimation or underestimation of homogeneous nucleation ratesITin the framework of classical nucleation theory (CNT). In this paper, a unique method able to distinguish the critical nucleus from numerous embryos is put forward on the basis of configuration heredities of clusters during rapid solidifications. As this technique is applied to analyze the formation and evolution of various fcc-Al single crystal clusters in a large-scale molecular dynamics simulation system, it is found that the sizencand geometrical configuration of critical nuclei as well as their liquid-solid interfacial structure can be determined directly. For the present deep super-cooled system with an undercooling ofTm=0.42Tmcal, the average size of critical nuclei is demonstrated to benc̄≈26, but most of which are non-spherical lamellae. Also, their liquid-solid interfaces are revealed to be not an fcc-liquid duplex-phase interface but an fcc/hcp-liquid multi-phase structure. These findings shed some lights on the CNT, and a good agreement with previous simulations and experiments inITindicates this technique can be used to explore the early-stage of nucleation from atomistic levels.
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Affiliation(s)
- Yuan Li
- School of Material Science & Engineering, Hunan University, Changsha 410082, People's Republic of China
| | - Ping Peng
- School of Material Science & Engineering, Hunan University, Changsha 410082, People's Republic of China
| | - Dongsheng Xu
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People's Republic of China
| | - Rui Yang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People's Republic of China
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6
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Hussain S, Haji-Akbari A. Role of Nanoscale Interfacial Proximity in Contact Freezing in Water. J Am Chem Soc 2021; 143:2272-2284. [PMID: 33507741 DOI: 10.1021/jacs.0c10663] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Contact freezing is a mode of atmospheric ice nucleation in which a collision between a dry ice nucleating particle (INP) and a water droplet results in considerably faster heterogeneous nucleation. The molecular mechanism of such an enhancement is, however, still a mystery. While earlier studies had attributed it to collision-induced transient perturbations, recent experiments point to the pivotal role of nanoscale proximity of the INP and the free interface. By simulating the heterogeneous nucleation of ice within INP-supported nanofilms of two model water-like tetrahedral liquids, we demonstrate that such nanoscale proximity is sufficient for inducing rate increases commensurate with those observed in contact freezing experiments, but only if the free interface has a tendency to enhance homogeneous nucleation. Water is suspected of possessing this latter property, known as surface freezing propensity. Our findings therefore establish a connection between the surface freezing propensity and kinetic enhancement during contact nucleation. We also observe that faster nucleation proceeds through a mechanism markedly distinct from classical heterogeneous nucleation, involving the formation of hourglass-shaped crystalline nuclei that conceive at either interface and that have a lower free energy of formation due to the nanoscale proximity of the interfaces and the modulation of the free interfacial structure by the INP. In addition to providing valuable insights into the physics of contact nucleation, our findings can assist in improving the accuracy of heterogeneous nucleation rate measurements in experiments and in advancing our understanding of ice nucleation on nonuniform surfaces such as organic, polymeric, and biological materials.
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Affiliation(s)
- Sarwar Hussain
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
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7
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Azimi Yancheshme A, Momen G, Jafari Aminabadi R. Mechanisms of ice formation and propagation on superhydrophobic surfaces: A review. Adv Colloid Interface Sci 2020; 279:102155. [PMID: 32305656 DOI: 10.1016/j.cis.2020.102155] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/02/2020] [Accepted: 04/06/2020] [Indexed: 12/25/2022]
Abstract
Icephobic surfaces, used as passive anti-icing materials, are in high demand due to the costs, damage, and loss of equipment and lives related to ice formation on outdoor surfaces. The proper design of icephobic surfaces is intertwined with the need for a profound understanding of ice formation processes and how ice propagates over a surface. Ice formation (ice nucleation) and interdroplet freezing propagation are processes that determine the onset of freezing and complete ice coverage on a surface, respectively. Evaluating the nature of these phenomena, along with their interactions with substrate and environmental factors, can offer a step toward designing surfaces having an improved icephobic performance. This review paper is organized to discuss ice nucleation and rate, preferable locations of nucleation, and favorable pathways of freezing (desublimation and condensation-freezing) on superhydrophobic surfaces. Furthermore, as the propagation of ice over a substrate plays a more deterministic role for the complete freezing coverage of a surface than that of ice formation, this review also elucidates possible mechanisms of ice propagation, theoretical backgrounds, and strategies to control this propagation using surface characteristics.
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8
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Yunusa M, Lahlou A, Sitti M. Thermal Effects on the Crystallization Kinetics, and Interfacial Adhesion of Single-Crystal Phase-Change Gallium. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907453. [PMID: 32009261 DOI: 10.1002/adma.201907453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/26/2019] [Indexed: 06/10/2023]
Abstract
Although substrates play an important role upon crystallization of supercooled liquids, the influences of surface temperature and thermal property have remained elusive. Here, the crystallization of supercooled phase-change gallium (Ga) on substrates with different thermal conductivity is studied. The effect of interfacial temperature on the crystallization kinetics, which dictates thermo-mechanical stresses between the substrate and the crystallized Ga, is investigated. At an elevated surface temperature, close to the melting point of Ga, an extended single-crystal growth of Ga on dielectric substrates due to layering effect and annealing is realized without the application of external fields. Adhesive strength at the interfaces depends on the thermal conductivity and initial surface temperature of the substrates. This insight can be applicable to other liquid metals for industrial applications, and sheds more light on phase-change memory crystallization.
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Affiliation(s)
- Muhammad Yunusa
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Aliénor Lahlou
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
- School of Medicine and School of Engineering, Koç University, 34450, Istanbul, Turkey
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9
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Hussain S, Haji-Akbari A. Studying rare events using forward-flux sampling: Recent breakthroughs and future outlook. J Chem Phys 2020; 152:060901. [DOI: 10.1063/1.5127780] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sarwar Hussain
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
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10
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Wang G, Guo Z. Liquid infused surfaces with anti-icing properties. NANOSCALE 2019; 11:22615-22635. [PMID: 31755495 DOI: 10.1039/c9nr06934h] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ice accretion on solid surfaces, a ubiquitous phenomenon that occurs in winter, brings much inconvenience to daily life and can even cause serious catastrophes. Icephobic surfaces, a passive way of processing surfaces to prevent surface destruction from ice accumulation, have attracted much attention from scientists because of their special ice-repellent properties, and many efforts have been made to rationally design durable icephobic coatings. This review is aimed at providing a brief and crucial overview of ice formation processes and feasible de-icing strategies. Here, the excellent anti-icing performance of liquid infused surfaces (LIS) inspired from Nepenthes is emphatically introduced. After a short introduction, the recent progresses in ice nucleation theory and ice adhesion decrease mechanism are comprehensively reviewed to gain a general understanding of the long freeze process and low ice adhesion on LIS. Subsequently, the anti-icing performance of LIS is systematically evaluated from four aspects regarding water repellence, condensation-frosting, long freeze process, and low ice adhesion. Finally, this review focuses on discussing the advantages and disadvantages of LIS and the potential measures to eliminate and alleviate these drawbacks.
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Affiliation(s)
- Guowei Wang
- Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, People's Republic of China. and State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
| | - Zhiguang Guo
- Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, People's Republic of China. and State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
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11
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Entropic colloidal crystallization pathways via fluid-fluid transitions and multidimensional prenucleation motifs. Proc Natl Acad Sci U S A 2019; 116:14843-14851. [PMID: 31285316 DOI: 10.1073/pnas.1905929116] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Complex crystallization pathways are common in protein crystallization, tetrahedrally coordinated systems, and biomineralization, where single or multiple precursors temporarily appear before the formation of the crystal. The emergence of precursors is often explained by a unique property of the system, such as short-range attraction, directional bonding, or ion association. But, structural characteristics of the prenucleation phases found in multistep crystallization remain unclear, and models are needed for testing and expanding the understanding of fluid-to-solid ordering pathways. Here, we report 3 instances of 2-step crystallization of hard-particle fluids. Crystallization in these systems proceeds via a high-density precursor fluid phase with prenucleation motifs in the form of clusters, fibers and layers, and networks, respectively. The density and diffusivity change across the fluid-fluid phase transition increases with motif dimension. We observe crystal nucleation to be catalyzed by the interface between the 2 fluid phases. The crystals that form are complex, including, notably, a crystal with 432 particles in the cubic unit cell. Our results establish the existence of complex crystallization pathways in entropic systems and reveal prenucleation motifs of various dimensions.
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12
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Falahati H, Haji-Akbari A. Thermodynamically driven assemblies and liquid-liquid phase separations in biology. SOFT MATTER 2019; 15:1135-1154. [PMID: 30672955 DOI: 10.1039/c8sm02285b] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The sustenance of life depends on the high degree of organization that prevails through different levels of living organisms, from subcellular structures such as biomolecular complexes and organelles to tissues and organs. The physical origin of such organization is not fully understood, and even though it is clear that cells and organisms cannot maintain their integrity without consuming energy, there is growing evidence that individual assembly processes can be thermodynamically driven and occur spontaneously due to changes in thermodynamic variables such as intermolecular interactions and concentration. Understanding the phase separation in vivo requires a multidisciplinary approach, integrating the theory and physics of phase separation with experimental and computational techniques. This paper aims at providing a brief overview of the physics of phase separation and its biological implications, with a particular focus on the assembly of membraneless organelles. We discuss the underlying physical principles of phase separation from its thermodynamics to its kinetics. We also overview the wide range of methods utilized for experimental verification and characterization of phase separation of membraneless organelles, as well as the utility of molecular simulations rooted in thermodynamics and statistical physics in understanding the governing principles of thermodynamically driven biological self-assembly processes.
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Affiliation(s)
- Hanieh Falahati
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA.
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13
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Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
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14
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Bi Y, Porras A, Li T. Free energy landscape and molecular pathways of gas hydrate nucleation. J Chem Phys 2018; 145:211909. [PMID: 28799352 DOI: 10.1063/1.4961241] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), pB histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the pB histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.
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Affiliation(s)
- Yuanfei Bi
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
| | - Anna Porras
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
| | - Tianshu Li
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
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15
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Bi Y, Xu E, Strobel TA, Li T. Formation of inclusion type silicon phases induced by inert gases. Commun Chem 2018. [DOI: 10.1038/s42004-018-0013-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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16
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Jiang H, Haji-Akbari A, Debenedetti PG, Panagiotopoulos AZ. Forward flux sampling calculation of homogeneous nucleation rates from aqueous NaCl solutions. J Chem Phys 2018; 148:044505. [DOI: 10.1063/1.5016554] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Hao Jiang
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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17
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Tang C, Harrowell P. Chemical ordering and crystal nucleation at the liquid surface: A comparison of Cu 50Zr 50 and Ni 50Al 50 alloys. J Chem Phys 2018; 148:044509. [PMID: 29390837 DOI: 10.1063/1.5010051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the influence of the liquid-vapor surface on the crystallization kinetics of supercooled metal alloys. While a good glass former, Cu50Zr50, shows no evidence of surface enhancement of crystallization, Ni50Al50 exhibits an increased rate of crystallization due to heterogeneous nucleation at the free liquid surface. The difference in the compositional fluctuations at the interface is proposed as the explanation of the distinction between the two alloys. Specifically, we observe compositional ordering at the surface of Ni50Al50, while the Cu50Zr50 alloy only exhibits a diffuse adsorption of the Cu at the interface. We argue that the general difference in composition susceptibilities at planar surfaces represents an important factor in understanding the difference in the glass forming ability of the two alloys.
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Affiliation(s)
- Chunguang Tang
- School of Materials Science and Engineering, University of New South Wales, New South Wales 2052, Australia
| | - Peter Harrowell
- School of Chemistry, The University of Sydney, New South Wales 2006, Australia
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18
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Abstract
Nucleation of acetaminophen glass at room temperature originates from ∼50 μm below the surface.
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Affiliation(s)
- Limin Shi
- Department of Pharmaceutics
- University of Minnesota
- Minneapolis
- USA
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19
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Wang XD, Jiang JZ. Perspective on Structural Evolution and Relations with Thermophysical Properties of Metallic Liquids. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703136. [PMID: 28940751 DOI: 10.1002/adma.201703136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 07/09/2017] [Indexed: 06/07/2023]
Abstract
The relationship between the structural evolution and properties of metallic liquids is a long-standing hot issue in condensed-matter physics and materials science. Here, recent progress is reviewed in several fundamental aspects of metallic liquids, including the methods to study their atomic structures, liquid-liquid transition, physical properties, fragility, and their correlations with local structures, together with potential applications of liquid metals at room temperature. Involved with more experimentally and theoretically advanced techniques, these studies provide more in-depth understanding of the structure-property relationship of metallic liquids and promote the design of new metallic materials with superior properties.
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Affiliation(s)
- Xiao-Dong Wang
- International Center for New-Structured Materials, School of Materials and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Jian-Zhong Jiang
- International Center for New-Structured Materials, School of Materials and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
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20
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Haji-Akbari A, Debenedetti PG. Perspective: Surface freezing in water: A nexus of experiments and simulations. J Chem Phys 2017; 147:060901. [DOI: 10.1063/1.4985879] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, USA
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21
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Park JM, Cho JH, Ha JH, Kim HS, Kim SW, Lee J, Chung KY, Cho BW, Choi HJ. Reversible crystalline-amorphous phase transformation in Si nanosheets with lithi-/delithiation. NANOTECHNOLOGY 2017; 28:255401. [PMID: 28548050 DOI: 10.1088/1361-6528/aa6dad] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Silicon (Si) has a large theoretical capacity of 4200 mAhg-1 and has great potential as a high-performance anode material for Li ion batteries (LIBs). Meanwhile, nanostructures can exploit the potential of Si and, accordingly, many zero-dimensional (0D) and one-dimensional (1D) Si nanostructures have been studied. Herein, we report on two-dimensional (2D) Si nanostructures, Si nanosheets (SiNSs), as anodes for LIBs. These 2D Si nanostructures, with a thickness as low 5 nm and widths of several micrometers, show reversible crystalline-amorphous phase transformations with the lithi-/delithiation by the dimensionality of morphology and large surface area. The reversible crystalline-amorphous phase transformation provides a structural stability of Li+ insertions and makes SiNSs promising candidates for reliable high-performance LIBs anode materials.
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Affiliation(s)
- Jeong Min Park
- Global E3 Institute and Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Republic of Korea. Energy Convergence Research Center, Korea Institute of Science and Technology, Seoul 130-650, Republic of Korea
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22
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Dong Z, Wang J, Zhou X. Effect of antifreeze protein on heterogeneous ice nucleation based on a two-dimensional random-field Ising model. Phys Rev E 2017; 95:052140. [PMID: 28618642 DOI: 10.1103/physreve.95.052140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Indexed: 11/07/2022]
Abstract
Antifreeze proteins (AFPs) are the key biomolecules that protect many species from suffering the extreme conditions. Their unique properties of antifreezing provide the potential of a wide range of applications. Inspired by the present experimental approaches of creating an antifreeze surface by coating AFPs, here we present a two-dimensional random-field lattice Ising model to study the effect of AFPs on heterogeneous ice nucleation. The model shows that both the size and the free-energy effect of individual AFPs and their surface coverage dominate the antifreeze capacity of an AFP-coated surface. The simulation results are consistent with the recent experiments qualitatively, revealing the origin of the surprisingly low antifreeze capacity of an AFP-coated surface when the coverage is not particularly high as shown in experiment. These results will hopefully deepen our understanding of the antifreeze effects and thus be potentially useful for designing novel antifreeze coating materials based on biomolecules.
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Affiliation(s)
- Zhen Dong
- School of Physical Sciences, University of Chinese Academy of Science, Beijing 100049, People's Republic of China
| | - Jianjun Wang
- Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Xin Zhou
- School of Physical Sciences, University of Chinese Academy of Science, Beijing 100049, People's Republic of China
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23
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Computational investigation of surface freezing in a molecular model of water. Proc Natl Acad Sci U S A 2017; 114:3316-3321. [PMID: 28292905 DOI: 10.1073/pnas.1620999114] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Water freezes in a wide variety of low-temperature environments, from meteors and atmospheric clouds to soil and biological cells. In nature, ice usually nucleates at or near interfaces, because homogenous nucleation in the bulk can only be observed at deep supercoolings. Although the effect of proximal surfaces on freezing has been extensively studied, major gaps in understanding remain regarding freezing near vapor-liquid interfaces, with earlier experimental studies being mostly inconclusive. The question of how a vapor-liquid interface affects freezing in its vicinity is therefore still a major open question in ice physics. Here, we address this question computationally by using the forward-flux sampling algorithm to compute the nucleation rate in a freestanding nanofilm of supercooled water. We use the TIP4P/ice force field, one of the best existing molecular models of water, and observe that the nucleation rate in the film increases by seven orders of magnitude with respect to bulk at the same temperature. By analyzing the nucleation pathway, we conclude that freezing in the film initiates not at the surface, but within an interior region where the formation of double-diamond cages (DDCs) is favored in comparison with the bulk. This, in turn, facilitates freezing by favoring the formation of nuclei rich in cubic ice, which, as demonstrated by us earlier, are more likely to grow and overcome the nucleation barrier. The films considered here are ultrathin because their interior regions are not truly bulk-like, due to their subtle structural differences with the bulk.
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24
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Yuan C, Smith RS, Kay BD. Communication: Distinguishing between bulk and interface-enhanced crystallization in nanoscale films of amorphous solid water. J Chem Phys 2017; 146:031102. [DOI: 10.1063/1.4974492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Chunqing Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - R. Scott Smith
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Bruce D. Kay
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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25
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Chen L, Cao CR, Shi JA, Lu Z, Sun YT, Luo P, Gu L, Bai HY, Pan MX, Wang WH. Fast Surface Dynamics of Metallic Glass Enable Superlatticelike Nanostructure Growth. PHYSICAL REVIEW LETTERS 2017; 118:016101. [PMID: 28106461 DOI: 10.1103/physrevlett.118.016101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Indexed: 06/06/2023]
Abstract
Contrary to the formation of complicated polycrystals induced by general crystallization, a modulated superlatticelike nanostructure, which grows layer by layer from the surface to the interior of a Pd_{40}Ni_{10}Cu_{30}P_{20} metallic glass, is observed via isothermal annealing below the glass transition temperature. The generation of the modulated nanostructure can be solely controlled by the annealing temperature, and it can be understood based on the fast dynamic and liquidlike behavior of the glass surface. The observations have implications for understanding the glassy surface dynamics and pave a way for the controllable fabrication of a unique and sophisticated nanostructure on a glass surface to realize the properties' modification.
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Affiliation(s)
- L Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - C R Cao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - J A Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Z Lu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Y T Sun
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - P Luo
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - L Gu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - H Y Bai
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - M X Pan
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - W H Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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26
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Shou W, Pan H. Silicon-wall interfacial free energy via thermodynamics integration. J Chem Phys 2016; 145:184702. [PMID: 27846694 DOI: 10.1063/1.4966975] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We compute the interfacial free energy of a silicon system in contact with flat and structured walls by molecular dynamics simulation. The thermodynamics integration method, previously applied to Lennard-Jones potentials [R. Benjamin and J. Horbach, J. Chem. Phys. 137, 044707 (2012)], has been extended and implemented in Tersoff potentials with two-body and three-body interactions taken into consideration. The thermodynamic integration scheme includes two steps. In the first step, the bulk Tersoff system is reversibly transformed to a state where it interacts with a structureless flat wall, and in a second step, the flat structureless wall is reversibly transformed into an atomistic SiO2 wall. Interfacial energies for liquid silicon-wall interfaces and crystal silicon-wall interfaces have been calculated. The calculated interfacial energies have been employed to predict the nucleation mechanisms in a slab of liquid silicon confined by two walls and compared with MD simulation results.
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Affiliation(s)
- Wan Shou
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri 65401, USA
| | - Heng Pan
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri 65401, USA
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27
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Ouyang W, Fu C, Sun Z, Xu S. Polymorph selection and nucleation pathway in the crystallization of Hertzian spheres. Phys Rev E 2016; 94:042805. [PMID: 27841599 DOI: 10.1103/physreve.94.042805] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Indexed: 06/06/2023]
Abstract
The crystallization process of Hertzian spheres is studied by means of molecular dynamics simulations in an NPT ensemble where the total number of particles N, the pressure P, and the temperature T are kept constant. It has been observed that the bond orientational ordering rather than the translational ordering (density) plays a primary role. The crystal polymorphs are determined by the state points. Under the conditions of small supercooling, the system is likely to be nucleated into crystals that have a preference for the metastable bcc structure, which can be regarded as a manifestation of the Alexander-McTague mechanism. In contrast, small nuclei are found to have a preference for fcc symmetry under conditions of a high degree of supercooling. Prestructured precursors that act as seeds and wet on the nuclei during nucleation always have a high degree of bcc-like ordering, despite different state points. The results above may provide a clue to the understanding of the crystallization process in core-softened particles.
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Affiliation(s)
- Wenze Ouyang
- Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Cuiliu Fu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zhiwei Sun
- Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shenghua Xu
- Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
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28
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Zhou HP, Xu M, Xu S, Liu LL, Liu CX, Kwek LC, Xu LX. Hydrogen-plasma-induced Rapid, Low-Temperature Crystallization of μm-thick a-Si:H Films. Sci Rep 2016; 6:32716. [PMID: 27600866 PMCID: PMC5013535 DOI: 10.1038/srep32716] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/11/2016] [Indexed: 11/18/2022] Open
Abstract
Being a low-cost, mass-production-compatible route to attain crystalline silicon, post-deposition crystallization of amorphous silicon has received intensive research interest. Here we report a low-temperature (300 °C), rapid (crystallization rate of ~17 nm/min) means of a-Si:H crystallization based on high-density hydrogen plasma. A model integrating the three processes of hydrogen insertion, etching, and diffusion, which jointly determined the hydrogenation depth of the excess hydrogen into the treated micrometer thick a-Si:H, is proposed to elucidate the hydrogenation depth evolution and the crystallization mechanism. The effective temperature deduced from the hydrogen diffusion coefficient is far beyond the substrate temperature of 300 °C, which implies additional driving forces for crystallization, i.e., the chemical annealing/plasma heating and the high plasma sheath electric field. The features of LFICP (low-frequency inductively coupled plasma) and LFICP-grown a-Si:H are also briefly discussed to reveal the underlying mechanism of rapid crystallization at low temperatures.
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Affiliation(s)
- H P Zhou
- School of Energy Science and Engineering, University of Electronic Science and Technology of China, 2006 Xiyuan Ave, West High-Tech Zone, Chengdu, 611731, China.,Plasma Sources and Application Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 637616, Singapore
| | - M Xu
- Key Laboratory of Information Materials of Sichuan Province &School of Electrical and Information Engineering, Southwest University for Nationalities, Chengdu 610041, China
| | - S Xu
- Plasma Sources and Application Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 637616, Singapore
| | - L L Liu
- Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - C X Liu
- Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - L C Kwek
- Centre for Quantum Technologies, National University of Singapore, 119077, Singapore
| | - L X Xu
- Plasma Sources and Application Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 637616, Singapore
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29
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Kortshagen UR, Sankaran RM, Pereira RN, Girshick SL, Wu JJ, Aydil ES. Nonthermal Plasma Synthesis of Nanocrystals: Fundamental Principles, Materials, and Applications. Chem Rev 2016; 116:11061-127. [DOI: 10.1021/acs.chemrev.6b00039] [Citation(s) in RCA: 248] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Uwe R. Kortshagen
- Department
of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - R. Mohan Sankaran
- Department
of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Rui N. Pereira
- Department
of Physics and I3N, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
- Walter
Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany
| | - Steven L. Girshick
- Department
of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jeslin J. Wu
- Department
of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Eray S. Aydil
- Department
of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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30
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Gianetti MM, Haji-Akbari A, Paula Longinotti M, Debenedetti PG. Computational investigation of structure, dynamics and nucleation kinetics of a family of modified Stillinger-Weber model fluids in bulk and free-standing thin films. Phys Chem Chem Phys 2016; 18:4102-11. [PMID: 26778494 DOI: 10.1039/c5cp06535f] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In recent years, computer simulations have found increasingly widespread use as powerful tools for studying phase transitions in wide variety of systems. In the particular and very important case of aqueous systems, the commonly used force-fields tend to offer quite different predictions with respect to a wide range of thermodynamic and kinetic properties, including the ease of ice nucleation, the propensity to freeze at a vapor-liquid interface, and the existence of a liquid-liquid phase transition. It is thus of fundamental and practical interest to understand how different features of a given water model affect its thermodynamic and kinetic properties. In this work, we use the forward-flux sampling technique to study the crystallization kinetics of a family of modified Stillinger-Weber (SW) potentials with energy (ε) and length (σ) scales taken from the monoatomic water (mW) model, but with different tetrahedrality parameters (λ). By increasing λ from 21 to 24, we observe the nucleation rate increases by 48 orders of magnitude at a supercooling of ζ = T/Tm = 0.845. Using classical nucleation theory, we are able to demonstrate that this change can largely be accounted for by the increase in |Δμ|, the thermodynamic driving force. We also perform rate calculations in freestanding thin films of the supercooled liquid, and observe a crossover from surface-enhanced crystallization at λ = 21 to bulk-dominated crystallization for λ ≥ 22.
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Affiliation(s)
- Melisa M Gianetti
- DQIAQF/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Amir Haji-Akbari
- Department of Chemical and Biological Engineering, Princeton University, Princeton NJ 08544, USA.
| | - M Paula Longinotti
- DQIAQF/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Pablo G Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton NJ 08544, USA.
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31
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Sosso G, Chen J, Cox SJ, Fitzner M, Pedevilla P, Zen A, Michaelides A. Crystal Nucleation in Liquids: Open Questions and Future Challenges in Molecular Dynamics Simulations. Chem Rev 2016; 116:7078-116. [PMID: 27228560 PMCID: PMC4919765 DOI: 10.1021/acs.chemrev.5b00744] [Citation(s) in RCA: 369] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 11/28/2022]
Abstract
The nucleation of crystals in liquids is one of nature's most ubiquitous phenomena, playing an important role in areas such as climate change and the production of drugs. As the early stages of nucleation involve exceedingly small time and length scales, atomistic computer simulations can provide unique insights into the microscopic aspects of crystallization. In this review, we take stock of the numerous molecular dynamics simulations that, in the past few decades, have unraveled crucial aspects of crystal nucleation in liquids. We put into context the theoretical framework of classical nucleation theory and the state-of-the-art computational methods by reviewing simulations of such processes as ice nucleation and the crystallization of molecules in solutions. We shall see that molecular dynamics simulations have provided key insights into diverse nucleation scenarios, ranging from colloidal particles to natural gas hydrates, and that, as a result, the general applicability of classical nucleation theory has been repeatedly called into question. We have attempted to identify the most pressing open questions in the field. We believe that, by improving (i) existing interatomic potentials and (ii) currently available enhanced sampling methods, the community can move toward accurate investigations of realistic systems of practical interest, thus bringing simulations a step closer to experiments.
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Affiliation(s)
- Gabriele
C. Sosso
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Ji Chen
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | | | - Martin Fitzner
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Philipp Pedevilla
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Andrea Zen
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Angelos Michaelides
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
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32
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Lü Y, Bi Q, Yan X. Density-wave-modulated crystallization in nanoscale silicon films and droplets. J Chem Phys 2016; 144:234508. [DOI: 10.1063/1.4953038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yongjun Lü
- School of Physics, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
- State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People’s Republic of China
| | - Qingling Bi
- School of Physics, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Xinqing Yan
- School of Physics, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
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33
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Toxvaerd S. Nucleation and droplet growth from supersaturated vapor at temperatures below the triple point temperature. J Chem Phys 2016; 144:164502. [DOI: 10.1063/1.4947475] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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34
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Metya AK, Singh JK, Müller-Plathe F. Ice nucleation on nanotextured surfaces: the influence of surface fraction, pillar height and wetting states. Phys Chem Chem Phys 2016; 18:26796-26806. [DOI: 10.1039/c6cp04382h] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Ice nucleation and growth on nanostructured surfaces.
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Affiliation(s)
- Atanu K. Metya
- Department of Chemical Engineering
- Indian Institute of Technology Kanpur
- Kanpur-208016
- India
| | - Jayant K. Singh
- Department of Chemical Engineering
- Indian Institute of Technology Kanpur
- Kanpur-208016
- India
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Center of Smart Interfaces
- Technische Universität Darmstadt
- D-64287 Darmstadt
- Germany
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35
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Całus S, Borowik L, Kityk AV, Eich M, Busch M, Huber P. Thermotropic interface and core relaxation dynamics of liquid crystals in silica glass nanochannels: a dielectric spectroscopy study. Phys Chem Chem Phys 2015; 17:22115-24. [PMID: 26255586 DOI: 10.1039/c5cp03039k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report dielectric relaxation spectroscopy experiments on two rod-like liquid crystals of the cyanobiphenyl family (5CB and 6CB) confined in tubular nanochannels with 7 nm radius and 340 micrometer length in a monolithic, mesoporous silica membrane. The measurements were performed on composites for two distinct regimes of fractional filling: monolayer coverage at the pore walls and complete filling of the pores. For the layer coverage a slow surface relaxation dominates the dielectric properties. For the entirely filled channels the dielectric spectra are governed by two thermally-activated relaxation processes with considerably different relaxation rates: a slow relaxation in the interface layer next to the channel walls and a fast relaxation in the core region of the channel filling. The strengths and characteristic frequencies of both relaxation processes have been extracted and analysed as a function of temperature. Whereas the temperature dependence of the static capacitance reflects the effective (average) molecular ordering over the pore volume and is well described within a Landau-de Gennes theory, the extracted relaxation strengths of the slow and fast relaxation processes provide an access to distinct local molecular ordering mechanisms. The order parameter in the core region exhibits a bulk-like behaviour with a strong increase in the nematic ordering just below the paranematic-to-nematic transition temperature TPN and subsequent saturation during cooling. By contrast, the surface ordering evolves continuously with a kink near TPN. A comparison of the thermotropic behaviour of the monolayer with the complete filling reveals that the molecular order in the core region of the pore filling affects the order of the peripheral molecular layers at the wall.
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Affiliation(s)
- Sylwia Całus
- Faculty of Electrical Engineering, Czestochowa University of Technology, 42-200 Czestochowa, Poland.
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36
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Sohn S, Jung Y, Xie Y, Osuji C, Schroers J, Cha JJ. Nanoscale size effects in crystallization of metallic glass nanorods. Nat Commun 2015; 6:8157. [PMID: 26323828 PMCID: PMC4569721 DOI: 10.1038/ncomms9157] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/26/2015] [Indexed: 11/10/2022] Open
Abstract
Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding.
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Affiliation(s)
- Sungwoo Sohn
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
| | - Yeonwoong Jung
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.,Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA
| | - Yujun Xie
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.,Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA
| | - Chinedum Osuji
- Department of Chemical &Environmental Engineering, Yale University, New Haven, Connecticut 06511, USA
| | - Jan Schroers
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
| | - Judy J Cha
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.,Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA
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37
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Shibuta Y, Oguchi K, Takaki T, Ohno M. Homogeneous nucleation and microstructure evolution in million-atom molecular dynamics simulation. Sci Rep 2015; 5:13534. [PMID: 26311304 PMCID: PMC4550917 DOI: 10.1038/srep13534] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/29/2015] [Indexed: 11/24/2022] Open
Abstract
Homogeneous nucleation from an undercooled iron melt is investigated by the statistical sampling of million-atom molecular dynamics (MD) simulations performed on a graphics processing unit (GPU). Fifty independent instances of isothermal MD calculations with one million atoms in a quasi-two-dimensional cell over a nanosecond reveal that the nucleation rate and the incubation time of nucleation as functions of temperature have characteristic shapes with a nose at the critical temperature. This indicates that thermally activated homogeneous nucleation occurs spontaneously in MD simulations without any inducing factor, whereas most previous studies have employed factors such as pressure, surface effect, and continuous cooling to induce nucleation. Moreover, further calculations over ten nanoseconds capture the microstructure evolution on the order of tens of nanometers from the atomistic viewpoint and the grain growth exponent is directly estimated. Our novel approach based on the concept of “melting pots in a supercomputer” is opening a new phase in computational metallurgy with the aid of rapid advances in computational environments.
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Affiliation(s)
- Yasushi Shibuta
- Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kanae Oguchi
- Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tomohiro Takaki
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Munekazu Ohno
- Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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38
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Direct calculation of ice homogeneous nucleation rate for a molecular model of water. Proc Natl Acad Sci U S A 2015; 112:10582-8. [PMID: 26240318 DOI: 10.1073/pnas.1509267112] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ice formation is ubiquitous in nature, with important consequences in a variety of environments, including biological cells, soil, aircraft, transportation infrastructure, and atmospheric clouds. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water. For molecular models, only indirect estimates have been obtained, e.g., by assuming the validity of classical nucleation theory. We use a path sampling approach to perform, to our knowledge, the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice, the most accurate among existing molecular models for studying ice polymorphs. By using a novel topological approach to distinguish different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice in the early stages of nucleation. In this competition, the cubic polymorph takes over because the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs, which give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph. This mechanism provides a molecular explanation for the earlier experimental and computational observations of the preference for cubic ice in the literature.
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39
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Schutzius TM, Jung S, Maitra T, Eberle P, Antonini C, Stamatopoulos C, Poulikakos D. Physics of icing and rational design of surfaces with extraordinary icephobicity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:4807-4821. [PMID: 25346213 DOI: 10.1021/la502586a] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Icing of surfaces is commonplace in nature and technology, affecting everyday life and sometimes causing catastrophic events. Understanding (and counteracting) surface icing brings with it significant scientific challenges that requires interdisciplinary knowledge from diverse scientific fields such as nucleation thermodynamics and heat transfer, fluid dynamics, surface chemistry, and surface nanoengineering. Here we discuss key aspects and findings related to the physics of ice formation on surfaces and show how such knowledge could be employed to rationally develop surfaces with extreme resistance to icing (extraordinary icephobicity). Although superhydrophobic surfaces with micro-, nano-, or (often biomimetic) hierarchical roughnesses have shown in laboratory settings (under certain conditions) excellent repellency and low adhesion to water down to temperatures near or below the freezing point, extreme icephobicity necessitates additional important functionalities. Other approaches, such as lubricant-impregnated surfaces, exhibit both advantages and serious limitations with respect to icing. In all, a clear path toward passive surfaces with extreme resistance to ice formation remains a challenge, but it is one well worth undertaking. Equally important to potential applications is scalable surface manufacturing and the ability of icephobic surfaces to perform reliably and sustainably outside the laboratory under adverse conditions. Surfaces should possess mechanical and chemical stability, and they should be thermally resilient. Such issues and related research directions are also addressed in this article.
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Affiliation(s)
- Thomas M Schutzius
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Stefan Jung
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Tanmoy Maitra
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Patric Eberle
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Carlo Antonini
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Christos Stamatopoulos
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering Department, ETH Zurich, 8092 Zurich, Switzerland
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40
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Całus S, Kityk AV, Eich M, Huber P. Inhomogeneous relaxation dynamics and phase behaviour of a liquid crystal confined in a nanoporous solid. SOFT MATTER 2015; 11:3176-3187. [PMID: 25759093 DOI: 10.1039/c5sm00108k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report filling-fraction dependent dielectric spectroscopy measurements on the relaxation dynamics of the rod-like nematogen 7CB condensed in 13 nm silica nanochannels. In the film-condensed regime, a slow interface relaxation dominates the dielectric spectra, whereas from the capillary-condensed state up to complete filling an additional, fast relaxation in the core of the channels is found. The temperature-dependence of the static capacitance, representative of the averaged, collective molecular orientational ordering, indicates a continuous, paranematic-to-nematic (P-N) transition, in contrast to the discontinuous bulk behaviour. It is well described by a Landau-de-Gennes free energy model for a phase transition in cylindrical confinement. The large tensile pressure of 10 MPa in the capillary-condensed state, resulting from the Young-Laplace pressure at highly curved liquid menisci, quantitatively accounts for a downward-shift of the P-N transition and an increased molecular mobility in comparison to the unstretched liquid state of the complete filling. The strengths of the slow and fast relaxations provide local information on the orientational order: the thermotropic behaviour in the core region is bulk-like, i.e. it is characterized by an abrupt onset of the nematic order at the P-N transition. By contrast, the interface ordering exhibits a continuous evolution at the P-N transition. Thus, the phase behaviour of the entirely filled liquid crystal-silica nanocomposite can be quantitatively described by a linear superposition of these distinct nematic order contributions.
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Affiliation(s)
- Sylwia Całus
- Faculty of Electrical Engineering, Czestochowa University of Technology, Al. Armii Krajowej 17, 42-200 Czestochowa, Poland.
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41
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Gurganus CW, Charnawskas JC, Kostinski AB, Shaw RA. Nucleation at the contact line observed on nanotextured surfaces. PHYSICAL REVIEW LETTERS 2014; 113:235701. [PMID: 25526136 DOI: 10.1103/physrevlett.113.235701] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Indexed: 06/04/2023]
Abstract
It has been conjectured that roughness plays a role in surface nucleation, the tendency for freezing to begin preferentially at the liquid-gas interface. Using high speed imaging, we sought evidence for freezing at the contact line on catalyst substrates with imposed characteristic length scales (texture). Length scales consistent with the critical nucleus size and with δ∼τ/σ, where τ is a relevant line tension and σ is the surface tension, range from nanometers to micrometers. It is found that nanoscale texture causes a shift in the nucleation of ice in supercooled water to the three-phase contact line, while microscale texture does not.
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Affiliation(s)
- C W Gurganus
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA
| | - J C Charnawskas
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA
| | - A B Kostinski
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA
| | - R A Shaw
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA and Atmospheric Sciences Program, Michigan Technological University, Houghton, Michigan 49931, USA
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42
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Haji-Akbari A, DeFever RS, Sarupria S, Debenedetti PG. Suppression of sub-surface freezing in free-standing thin films of a coarse-grained model of water. Phys Chem Chem Phys 2014; 16:25916-27. [PMID: 25354427 DOI: 10.1039/c4cp03948c] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Freezing in the vicinity of water-vapor interfaces is of considerable interest to a wide range of disciplines, most notably the atmospheric sciences. In this work, we use molecular dynamics and two advanced sampling techniques, forward flux sampling and umbrella sampling, to study homogeneous nucleation of ice in free-standing thin films of supercooled water. We use a coarse-grained monoatomic model of water, known as mW, and we find that in this model a vapor-liquid interface suppresses crystallization in its vicinity. This suppression occurs in the vicinity of flat interfaces where no net Laplace pressure in induced. Our free energy calculations reveal that the pre-critical crystalline nuclei that emerge near the interface are thermodynamically less stable than those that emerge in the bulk. We investigate the origin of this instability by computing the average asphericity of nuclei that form in different regions of the film, and observe that average asphericity increases closer to the interface, which is consistent with an increase in the free energy due to increased surface-to-volume ratios.
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Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
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43
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Artyukhov VI, Pulver AY, Peregudov A, Artyuhov I. Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water–Xe system. J Chem Phys 2014; 141:034503. [DOI: 10.1063/1.4887069] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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44
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Bi Y, Li T. Probing methane hydrate nucleation through the forward flux sampling method. J Phys Chem B 2014; 118:13324-32. [PMID: 24849698 DOI: 10.1021/jp503000u] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Understanding the nucleation of hydrate is the key to developing effective strategies for controlling methane hydrate formation. Here we present a computational study of methane hydrate nucleation, by combining the forward flux sampling (FFS) method and the coarse-grained water model mW. To facilitate the application of FFS in studying the formation of methane hydrate, we developed an effective order parameter λ on the basis of the topological analysis of the tetrahedral network. The order parameter capitalizes the signature of hydrate structure, i.e., polyhedral cages, and is capable of efficiently distinguishing hydrate from ice and liquid water while allowing the formation of different hydrate phases, i.e., sI, sII, and amorphous. Integration of the order parameter λ with FFS allows explicitly computing hydrate nucleation rates and obtaining an ensemble of nucleation trajectories under conditions where spontaneous hydrate nucleation becomes too slow to occur in direct simulation. The convergence of the obtained hydrate nucleation rate was found to depend crucially on the convergence of the spatial distribution for the spontaneously formed hydrate seeds obtained from the initial sampling of FFS. The validity of the approach is also verified by the agreement between the calculated nucleation rate and that inferred from the direct simulation. Analyzing the obtained large ensemble of hydrate nucleation trajectories, we show hydrate formation at 220 K and 500 bar is initiated by the nucleation events occurring in the vicinity of water-methane interface, and facilitated by a gradual transition from amorphous to crystalline structure. The latter provides the direct support to the proposed two-step nucleation mechanism of methane hydrate.
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Affiliation(s)
- Yuanfei Bi
- Department of Civil and Environmental Engineering, George Washington University , Washington, D.C. 20052, United States
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45
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Lopez T, Mangolini L. Low activation energy for the crystallization of amorphous silicon nanoparticles. NANOSCALE 2014; 6:1286-1294. [PMID: 24326353 DOI: 10.1039/c3nr02526h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have experimentally determined the crystallization rate of plasma-produced amorphous silicon powder undergoing in-flight thermal annealing, and have found a significant reduction in the activation energy for crystallization compared to amorphous silicon thin films. This finding allows us to shed light onto the mechanism leading to the formation of high quality nanocrystals in non-thermal plasmas.
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Affiliation(s)
- Thomas Lopez
- Mechanical Engineering Department, Materials Science and Engineering Program, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA.
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46
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Li T, Donadio D, Galli G. Ice nucleation at the nanoscale probes no man's land of water. Nat Commun 2013; 4:1887. [PMID: 23695681 DOI: 10.1038/ncomms2918] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 04/18/2013] [Indexed: 11/09/2022] Open
Abstract
At a given thermodynamic condition, nucleation events occur at a frequency that scales with the volume of the system. Therefore at the nanoscale, one may expect to obtain supercooled liquids below the bulk homogeneous nucleation temperature. Here we report direct computational evidence that in supercooled water nano-droplets ice nucleation rates are strongly size dependent and at the nanoscale they are several orders of magnitude smaller than in bulk water. Using a thermodynamic model based on classical nucleation theory, we show that the Laplace pressure is partially responsible for the suppression of ice crystallization. Our simulations show that the nucleation rates found for droplets are similar to those of liquid water subject to a pressure of the order of the Laplace pressure within droplets. Our findings aid the interpretation of molecular beam experiments and support the hypothesis of surface crystallization of ice in microscopic water droplets in clouds.
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Affiliation(s)
- Tianshu Li
- Department of Civil and Environmental Engineering, George Washington University, Washington, District of Columbia 20052, USA.
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47
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Sanz E, Vega C, Espinosa JR, Caballero-Bernal R, Abascal JLF, Valeriani C. Homogeneous Ice Nucleation at Moderate Supercooling from Molecular Simulation. J Am Chem Soc 2013; 135:15008-17. [DOI: 10.1021/ja4028814] [Citation(s) in RCA: 214] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- E. Sanz
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Vega
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J. R. Espinosa
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - R. Caballero-Bernal
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J. L. F. Abascal
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Valeriani
- Departamento
de Química
Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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48
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Filipponi A, Di Cicco A, Principi E. Crystalline nucleation in undercooled liquids: a Bayesian data-analysis approach for a nonhomogeneous Poisson process. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:066701. [PMID: 23368072 DOI: 10.1103/physreve.86.066701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Indexed: 06/01/2023]
Abstract
A Bayesian data-analysis approach to data sets of maximum undercooling temperatures recorded in repeated melting-cooling cycles of high-purity samples is proposed. The crystallization phenomenon is described in terms of a nonhomogeneous Poisson process driven by a temperature-dependent sample nucleation rate J(T). The method was extensively tested by computer simulations and applied to real data for undercooled liquid Ge. It proved to be particularly useful in the case of scarce data sets where the usage of binned data would degrade the available experimental information.
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Affiliation(s)
- A Filipponi
- Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell'Aquila, I-67100 Coppito, L'Aquila, Italy.
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49
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Jung S, Tiwari MK, Doan NV, Poulikakos D. Mechanism of supercooled droplet freezing on surfaces. Nat Commun 2012; 3:615. [DOI: 10.1038/ncomms1630] [Citation(s) in RCA: 422] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 12/01/2011] [Indexed: 11/09/2022] Open
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50
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Selli D, Boulfelfel SE, Baburin IA, Seifert G, Leoni S. Framework reconstruction between hR8 and cI16 germaniums: A molecular dynamics study. RSC Adv 2012. [DOI: 10.1039/c2ra20837g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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