Crystal-liquid interfaces and phase relations in stable and metastable silicon at positive and negative pressure

Daisenberger, Dominik; McMillan, Paul F.; Wilson, Mark

doi:10.1103/physrevb.82.214101

Cited by 13 publications

(17 citation statements)

References 51 publications

(43 reference statements)

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“…Such growth behavior is consistent across the multiple trajectories that were examined at the temperatures of 260-270 K. The crystallographic faces of the newly formed hydrate crystal that contact with the gas aqueous solution are dominated by [100] instead of [110] faces, where the latter has been suggested to be the slowest growing for methane hydrates. 65 While various factors may be responsible for the promotion/inhibition of the crystallization with different solid/liquid interface structures, 66 the current study indicates unfavorable growth conditions for the methane hydrate near the silica surfaces. We observe a layer of rather disordered water molecules in the vicinity of both silica surfaces (see Fig.…”

Section: Crystal Growth Under Apparent Steady-state Conditionsmentioning

confidence: 67%

Crystal growth simulations of methane hydrates in the presence of silica surfaces

Liang

Rozmanov

Kusalik

2011

Phys. Chem. Chem. Phys.

111

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We present a molecular dynamics simulation study of the crystal growth of methane hydrates in the presence of model silica (SiO(2)) surfaces. The crystal growth under apparent steady-state conditions shows a clear preference for bulk solution. We observe rather disordered water arrangements very close to the silica surface within about 5 Å in both liquid and crystalline regions of the system. These disordered structures have dynamic and structural properties intermediate between those exhibited by molecules in bulk liquid and crystalline phases. The presence of methane molecules appears to help stabilize these structures. We observe that under appropriate conditions, the hydroxylated silica surfaces can serve as a source of methane molecules which can help promote hydrate growth near the surfaces.

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Section: Crystal Growth Under Apparent Steady-state Conditionsmentioning

confidence: 67%

Crystal growth simulations of methane hydrates in the presence of silica surfaces

Liang

Rozmanov

Kusalik

2011

Phys. Chem. Chem. Phys.

111

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“…We use molecular dynamics (MD) simulations with the Stillinger−Weber (SW) potential to investigate the phase behavior of two layers of silicon confined between two parallel smooth Lennard-Jones 9−3 (L-J-93) walls. The SW silicon model is best among empirical potentials in reproducing the experimental melting temperature T m of the bulk diamond cubic crystal at 1 atm; it adequately reproduces the melting line of that crystal up to pressures of about 7 GPa, and it predicts a melting temperature for the Si 136 guest-free silicon clathrate crystal in excellent agreement with experiments . The fidelity of the model in reproducing the liquid−crystal equilibrium of Si 136 is significant for this work because pentagonal silicon rings predominate in that crystal which is exclusively tiled with dodecahedra and hexakaidecahedra.…”

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confidence: 70%

A Single-Component Silicon Quasicrystal

Johnston

Phippen

Molinero

2011

J. Phys. Chem. Lett.

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Quasicrystals are structures with long-range order and no translational periodicity. Monatomic quasicrystals were predicted for model potentials, but no single-component atomic quasicrystal of an actual element has been reported to date. A dodecagonal quasicrystal was recently predicted to form in bilayer water. Water and silicon present striking similarities in their phase behavior, raising the question of whether quasicrystals may occur in silicon. Here, we show, using molecular simulations, that a confined silicon bilayer forms a quasicrystal upon compression between smooth surfaces. The quasicrystal is stable in a narrow region of the phase diagram and forms spontaneously upon cooling the liquid bilayer in a wide range of pressures. Cooling the liquid between atomically detailed plates incommensurate with the quasicrystal leads to its spontaneous formation at 1 atm of lateral pressure. This suggests that the silicon quasicrystal could be obtained in experiments at room pressure by tuning the structure and interactions of the surfaces.

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“…It is interesting to note that clathrate topologies (e.g., type II mtn and type I mep) are calculated to be thermodynamic ground states under hydrostatic tension (negative pressure). 42,43 At any particular P,T condition, there will exist one thermodynamic ground state (e.g., DC-Si at standard conditions), yet multitudes of metastable forms will exhibit energetic feasibility (i.e., favorable energetics not far from the ground state making them potentially kinetically stable at ambient conditions). Thousands of such energetically competitive, low-density structures have been computed, and numerous high-density forms are reasonable at elevated pressure.…”

Section: B Many New Forms Of Silicon Are Plausiblementioning

confidence: 99%

Pathways to exotic metastable silicon allotropes

Haberl

Strobel

Bradby

2016

Applied Physics Reviews

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The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, significant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. This review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner.

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Crystal-liquid interfaces and phase relations in stable and metastable silicon at positive and negative pressure

Cited by 13 publications

References 51 publications

Crystal growth simulations of methane hydrates in the presence of silica surfaces

Crystal growth simulations of methane hydrates in the presence of silica surfaces

A Single-Component Silicon Quasicrystal

Pathways to exotic metastable silicon allotropes

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