Observations on the nucleation of ice VII in compressed water

Chapman, David J.; Bland, S. N.; Eakins, Daniel E.

doi:10.1063/1.4971716

Cited by 15 publications

(24 citation statements)

References 7 publications

(10 reference statements)

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“…through heterogeneous nucleation of ice VII along the window surfaces. On the other hand, if the peak pressure goes beyond the metastability limit of 6-7 GPa, freezing achieves completion within just a few tens of nanoseconds, and it does so regardless of the window material (i.e., even with sapphire windows) [10,11,13]. This material-independent behavior suggests that freezing at these deeply undercooled conditions is dominated by homogeneous nucleation within the bulk of the water.…”

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confidence: 99%

“…At this low pressure, it is difficult to deeply undercool liquid water [5,6], and so the driving force for freezing is rather limited in magnitude. In contrast, water becomes deeply undercooled (by up to 150 degrees; see Figure 1) and remains as a metastable liquid for less than a microsecond in dynamic compression experiments performed over the past two decades where it is rapidly compressed along a quasi-isentrope to pressures above 1 GPa [7][8][9][10][11][12][13][14]. Some of these experiments have achieved peak pressures of above 6 GPa [10,11,13], and their conclusion is that water freezes almost instantaneously -within a few tens of nanoseconds -if it gets overdriven to this point along the quasi-isentrope.…”

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confidence: 99%

“…In contrast, previously published simulations of these "null result" experiments have artificially disallowed freezing by removing the ice VII phase from their EOS (i.e., running liquid-only models), rather than allowing a model of the kinetics to determine the final state [9,[11][12][13]18]. The ability to reproduce this null result is an important test of our CNT-based framework, and we show in the SM that it successfully reproduces similar experiments from Dolan and Gupta et al [9] and Stafford et al [13] We have explained how a theoretical framework built on CNT and growth, when combined with hydrodynamics simulations, provides quantitative agreement with experimental pressure wave profiles associated with nanosecond freezing kinetics of liquid water to ice VII via homogeneous nucleation. This is the first such demonstration of a single, unified framework that can match the phase transition kinetics observed in multiple different dynamic compression experiments.…”

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confidence: 99%

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Nanosecond Freezing of Water at High Pressures: Nucleation and Growth near the Metastability Limit

et al. 2018

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The fundamental study of phase transition kinetics has motivated experimental methods toward achieving the largest degree of undercooling possible, more recently culminating in the technique of rapid, quasi-isentropic compression. This approach has been demonstrated to freeze water into the high-pressure ice VII phase on nanosecond time scales, with some experiments undergoing heterogeneous nucleation while others, in apparent contradiction, suggesting a homogeneous nucleation mode. In this study, we show through a combination of theory, simulation, and analysis of experiments that these seemingly contradictory results are in agreement when viewed from the perspective of classical nucleation theory. We find that, perhaps surprisingly, classical nucleation theory is capable of accurately predicting the solidification kinetics of ice VII formation under an extremely high driving force (|∆µ/k B T | ≈ 1), but only if amended by two important considerations: 1) transient nucleation and 2) separate liquid and solid temperatures. This is the first demonstration of a model that is able to reproduce the experimentally observed rapid freezing kinetics.

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Nanosecond Freezing of Water at High Pressures: Nucleation and Growth near the Metastability Limit

et al. 2018

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“…These factors include the strength of the interactions between atoms or molecules and interfacial entropy differences between the two phases that influence the configuration of atoms or molecules at the interface. In this work, we develop a solid–liquid interfacial free-energy model for high-pressure conditions, such as those encountered in dynamic-compression experiments that use shock and ramp waves to rapidly compress a liquid sample to high pressures that lie deep within the stability field of solid. − The compression transiently leads to a metastable liquid that is undercooled far below the melt temperature before it eventually solidifies, allowing one to probe phase transition kinetics at extreme pressures. These highly non-equilibrium conditions present additional challenges for characterizing the solid–liquid interface and developing a model for computing the interfacial free energy.…”

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confidence: 99%

Model for the Solid–Liquid Interfacial Free Energy at High Pressures

et al. 2022

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The free energy involved in the formation of an interface between two phases (e.g., a solid−liquid interface) is referred to as the interfacial free energy. For the case of solidification, the interfacial free energy dictates the height of the energy barrier required to nucleate stable clusters of the newly forming solid phase and is essential for producing an accurate solidification kinetics model using classical nucleation theory (CNT)-based methods. While various methods have been proposed for modeling the interfacial free energy for solid−liquid interfaces in prior literature, many of these formulations involve making restrictive assumptions or approximations, such as the system being at or near equilibrium (i.e., the system temperature is approximately equal to the melt temperature) or that the system is at pressures close to atmospheric. However, these approximations and assumptions may break down in highly non-equilibrium situations, such as in dynamic-compression experiments where metastable liquids that are undercooled by hundreds of kelvin or overpressurized by several gigapascals or more are formed before eventually solidifying. We derive a solid−liquid interfacial free-energy model for such high-pressure conditions by considering the enthalpies of interactions between pairs of atoms or molecules. We also consider the contribution of interface roughness (disordering) by incorporating a multilayer interface model known as the Temkin n-layer model. Our formulation is applicable to a diverse variety of materials, and we demonstrate it by developing models specifically for two different materials: water and gallium. We apply our interfacial free-energy formulation to CNT-based kinetics simulations of several suites of dynamic-compression experiments that cause liquid water to solidify to the high-pressure solid polymorph ice VII and have found good agreement to the observed kinetics with only minor empirical fitting.

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“…Recent powerful advances in dynamic shock/ramp compression techniques ( 15 – 23 ) have been able to achieve melting and solidification at rates that can exceed rapid cooling techniques described above. Hence, extreme undercoolings can be achieved in these experiments, and therefore, the limits of the current theories of phase transformation kinetics can be tested.…”

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Metastable–solid phase diagrams derived from polymorphic solidification kinetics

Sadigh

Zepeda-Ruiz

Belof

2021

Proc. Natl. Acad. Sci. U.S.A.

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Nonequilibrium processes during solidification can lead to kinetic stabilization of metastable crystal phases. A general framework for predicting the solidification conditions that lead to metastable-phase growth is developed and applied to a model face-centered cubic (fcc) metal that undergoes phase transitions to the body-centered cubic (bcc) as well as the hexagonal close-packed phases at high temperatures and pressures. Large-scale molecular dynamics simulations of ultrarapid freezing show that bcc nucleates and grows well outside of the region of its thermodynamic stability. An extensive study of crystal–liquid equilibria confirms that at any given pressure, there is a multitude of metastable solid phases that can coexist with the liquid phase. We define for every crystal phase, a solid cluster in liquid (SCL) basin, which contains all solid clusters of that phase coexisting with the liquid. A rigorous methodology is developed that allows for practical calculations of nucleation rates into arbitrary SCL basins from the undercooled melt. It is demonstrated that at large undercoolings, phase selections made during the nucleation stage can be undone by kinetic instabilities amid the growth stage. On these bases, a solidification–kinetic phase diagram is drawn for the model fcc system that delimits the conditions for macroscopic grains of metastable bcc phase to grow from the melt. We conclude with a study of unconventional interfacial kinetics at special interfaces, which can bring about heterogeneous multiphase crystal growth. A first-order interfacial phase transformation accompanied by a growth-mode transition is examined.

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Observations on the nucleation of ice VII in compressed water

Cited by 15 publications

References 7 publications

Nanosecond Freezing of Water at High Pressures: Nucleation and Growth near the Metastability Limit

Nanosecond Freezing of Water at High Pressures: Nucleation and Growth near the Metastability Limit

Model for the Solid–Liquid Interfacial Free Energy at High Pressures

Metastable–solid phase diagrams derived from polymorphic solidification kinetics

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