On the clathrate form of elemental silicon, Si136: preparation and characterisation of NaxSi136 (x→0)

Ammar, A.; Cros, C.; Pouchard, Michel; Jaussaud, Nicolas; Bassat, Jean‐Marc; Villeneuve, G.; Duttine, Mathieu; Ménétrier, Michel; Reny, E.

doi:10.1016/j.solidstatesciences.2004.02.006

Cited by 107 publications

(103 citation statements)

References 22 publications

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“…In contrast, in the semiconducting clathrates, the cages are typically occupied by alkaline, earth-alkaline, or halogen atoms and there is a strong ionic interaction between the guests and the tetrahedrally coordinated framework. [7] However, in the case of cubic clathrate-II framework (Figure 1), practically "guest-free" modifications have been synthetized, [8][9][10] in line with computational studies showing the clathrate-II framework to be the energetically the most favorable one within various experimentally observed and hypothetical clathrate frameworks. [11] Recent synthesis of alloyed, guest-free SiGe clathrates is a promising step in the direction of tunable band gap materials for optoelectronic applications.…”

Section: Introductionsupporting

confidence: 65%

“…Ionic liquids have already been used to synthesize the practically guest-free Ge clathrate-II via oxidation of Ge 9 4-Zintl anions. [10] Noble gas atoms are readily soluble in ionic liquids [49,50] and if the oxidation of the M 9 4-anions is carried out in an ionic liquid with a noble gas high concentration, the translational entropy of the noble gas atoms has already been greatly reduced during the solvation to the ionic liquid. Hence, the entropy loss due inclusion in the clathrate structure would not be so drastic and the noble gas inclusion within the clathrate framework could become thermodynamically favoured.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, vacuum treatment of the clathrate structures has been shown to allow efficient manipulation of the host-guest structure, as the practically guest-free Si clathrate-II structure could be prepared via ultra-high vacuum treatment of Na x Si 136 . [9] …”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]

Karttunen

Fässler

2014

Chemistry A European J

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Section: Introductionsupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

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Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]

Karttunen

Fässler

2014

Chemistry A European J

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“…While guest molecules are necessary for stabilization of the open lattice structure of 3D gas clathrates of water at ambient pressure, it is known that a guest-free clathrate of germanium can be synthesized (16), and an almost empty clathrate of Si has been described (17,18). The latter can definitely be formed in simulations with the Stillinger-Weber potential (19).…”

Section: Resultsmentioning

confidence: 99%

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Bai

Angell

Zeng

2010

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

101

127

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Three-dimensional (3D) gas clathrates are ice-like but distinguished from bulk ices by containing polyhedral nano-cages to accommodate small gas molecules. Without space filling by gas molecules, standalone 3D clathrates have not been observed to form in the laboratory, and they appear to be unstable except at negative pressure. Thus far, experimental evidence for guest-free clathrates has only been found in germanium and silicon, although guest-free hydrate clathrates have been found, in recent simulations, able to grow from cold stretched water, if first nucleated. Herein, we report simulation evidence of spontaneous formation of monolayer clathrate ice, with or without gas molecules, within hydrophobic nano-slit at low temperatures. The guest-free monolayer clathrate ice is a low-density ice (LDI) whose geometric pattern is identical to Archimedean 4 · 8 2 -truncated square tiling, i.e. a mosaic of tetragons and octagons. At large positive pressure, a second phase of 2D monolayer ice, i.e. the puckered square high-density ice (HDI) can form. The triple point of the LDI/liquid/HDI three-phase coexistence resembles that of the ice-I h ∕water∕ice-III three-phase coexistence. More interestingly, when the LDI is under a strong compression at 200 K, it transforms into the HDI via a liquid intermediate state, the first direct evidence of Ostwald's rule of stages at 2D. The tensile limit of the 2D LDI and water are close to that of bulk ice-I h and laboratory water.2D high-density ice | 2D low-density ice | 2D monolayer ice clathrate | Ostwald rule of stages | tensile limit of 2D liquid N atural gas is largely reserved in nature in the form of gas clathrates on the world's ocean floors (1-7). In the laboratory, gas clathrates can be produced by bringing a nonpolar gas in direct contact with liquid water under moderate pressure and at low temperature (1,(8)(9)(10)(11)). Since gas clathrates possess an open-cage structure to accommodate small gas molecules, gas clathrates can be characterized by two parameters: (1) the minimum gas pressure needed to stabilize the clathrates, and (2) the degree of occupancy or the fraction of cages occupied by the gas molecules. Although structural and thermodynamic properties of many gas clathrates are well characterized, the kinetic process of 3D clathrate formation is still less understood (1, 12). In an attempt to gain molecular insight into kinetics of clathrate formation, we carried out molecular dynamics (MD) simulations of clathrate formation within a slit nanopore whose width D is on the scale of 0.6 nm (see Materials and Methods). Because the slit nanopore can only accommodate one molecular layer of water, the timescale required for the formation of the quasi-2D gas clathrate is within the reach of MD simulation (typically 10-10 2 ns). Results and DiscussionsWe first considered a binary fluid mixture of water and argon (with 11.1% mole fraction of Ar) confined to the slit nanopore (D ¼ 0.62 nm) whose two opposing walls are smooth and hydrophobic (13-15). The fluid mixture was ...

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“…Computationally, many novel well-ordered Si allotropes of various dimensionality have been proposed [9,10], but only a few of those were experimentally verified, such as the low-density Si allotropes [11] with clathrate-type structures [12][13][14][15][16][17][18][19]. The focus of the research lies on the description, understanding, and discovery of well-performing photovoltaic materials as well as models for bulk silicon surfaces [20,21].…”

Section: Introductionmentioning

confidence: 99%

Predicted Siliconoids by Bridging Si9 Clusters through sp3-Si Linkers

Jantke

Fässler

2018

Inorganics

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Charged and neutral silicon clusters comprising Si atoms that are exclusively connected to atoms of the same type serve as models for bulk silicon surfaces. The experimentally known nido-[Si 9 ] 4− Zintl cluster is investigated as a building block and allows for a theoretical prediction of novel silicon-rich oligomers and polymers by interconnection of such building units to larger aggregates. The stability and electronic properties of the polymers { 12 ) n }, as well as of related oligomers are presented.

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On the clathrate form of elemental silicon, Si136: preparation and characterisation of NaxSi136 (x→0)

Cited by 107 publications

References 22 publications

Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]

Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Predicted Siliconoids by Bridging Si9 Clusters through sp3-Si Linkers

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On the clathrate form of elemental silicon, Si136: preparation and characterisation of NaxSi136 (x→0)

Cited by 107 publications

References 22 publications

Semiconducting Clathrates Meet Gas Hydrates: Xe24[Sn136]

Semiconducting Clathrates Meet Gas Hydrates: Xe24[Sn136]

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Predicted Siliconoids by Bridging Si9 Clusters through sp3-Si Linkers

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Product

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Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]

Semiconducting Clathrates Meet Gas Hydrates: Xe₂₄[Sn₁₃₆]