On the structure of amorphous germanium and silicon

Weinstein, Frank C.; Davis, E. A.

doi:10.1016/0022-3093(73)90044-6

Cited by 36 publications

(4 citation statements)

References 31 publications

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“…44,52,53 It is worth noting that the predominance of pentagonal rings in the clathrate structure leads some authors to use clathrates as crystalline prototypes of amorphous silicon or germanium. 65 Recent works combining high-quality x-ray synchrotron sources and molecular dynamics have been used to investigate high-pressure amorphous structures. 53,66 In addition, pressure-induced amorphization is commonly observed in cagelike crystals.…”

Section: ͒mentioning

confidence: 99%

High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrateRb6.15Si46

et al. 2009

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The type-I clathrate Rb 6.15 Si 46 with partly empty cage sites has been studied up to 36 GPa using Raman spectroscopy, synchrotron x-ray diffraction in diamond-anvil cells, and ab initio total-energy and latticedynamics calculations. A first phase transition is observed at 13Ϯ 1 GPa and a "volume collapse" transition within the clathrate structure is then observed at 24Ϯ 1 GPa. Pressure-induced amorphization into a highdensity amorphous ͑HDA͒ state occurs above P =33Ϯ 1 GPa. The HDA form transforms into a low-density amorphous polymorph during decompression. During the compression study using angle dispersive synchrotron x-ray diffraction techniques we measured bulk modulus parameters for rocksalt-structured TaO, included adventitiously in the clathrate sample ͓K 0 = 293͑3͒ GPa and K 0 Ј=5.4͑3͔͒.

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Section: ͒mentioning

confidence: 99%

High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrateRb6.15Si46

et al. 2009

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“…This approach was first used by Konnert, Karle & Ferguson (1973) and described further by D'Antonio, Moore, Konnert & Karle (1977). Other related procedures have been suggested by Duffy, Boudreaux & Polk (1974) and Weinstein & Davis (1974).…”

Section: Computer Programsmentioning

confidence: 99%

Computer program for radial distribution calculation from known bonding topologies

D’Antonio¹,

Konnert²

1980

J Appl Crystallogr

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“…In tetrahedral amorphous materials, planar pentagonal rings can interface directly with crystalline structural motifs because these rings possess internal bond angles of 108°, which is close to the ideal tetrahedral angle of 109.47° formed in boat- and chair-shaped six-membered rings. − The early structural studies of amorphous silicon and germanium concluded that a combination of five- and six-membered rings is essential to produce the features of radial distribution functions (RDFs) generated from experiments. − Further, these studies also indicated that the amorphous structure involves cages formed by planar pentagonal and hexagonal rings. Recent investigations on ice crystallized on surfaces have confirmed the presence of pentagonal rings in a variety of mesoscopic environments. , Metastable ice clusters, known as clathrate hydrates, also contain cages formed by planar pentagonal and hexagonal rings, which are stabilized by trapped gas molecules .…”

Section: Introductionmentioning

confidence: 99%

Topological Identification Criteria, Stability, and Relevance of Pentagonal Nanochannels in Amorphous Ice

Pingua

Apte

2019

J. Phys. Chem. B

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Considering the potential importance of pentagonal nanochannels (PNCs) in determining the structure of the amorphous ice, we introduce topological criteria to identify the PNCs with an optimal fivefold symmetric environment. The basic building block in our criteria, termed as a bicyclo octamer, is an axisymmetric cluster formed by combination of three 6-membered boat-shaped rings. This bicyclo octamer unit serves as a seamless interface of the PNCs with cubic-hexagonal stacking patterns of the amorphous ice. This interface results in a fivefold symmetric mesostructure of relatively high stability: a central PNC with extended five branches of two-dimensional (2-D) hexagonal (wurtzite) crystalline monolayers stacked with cubic (diamond) layers. We also unearth a hierarchy of symmetric structures in amorphous ice: the PNCs, together with dodecahedron cages, form a network consisting of (nearly) equilateral triangular patterns. At the next hierarchical level of symmetry, such triangular patterns combine to form triangular pyramids with dodecahedron cages as the vertices, PNCs as the edges, and confined 2-D hexagonal crystalline monolayers as the triangular faces of the pyramids. The central core of the pyramids consists of cubic (diamond) regions with a strong local tetrahedral order. The overall structure of the amorphous ice states is found to be profoundly affected by PNCs. Specifically, in states with a relatively large number of PNCs, the cubic-hexagonal stacking is primarily in the form of hexagonal crystalline monolayers stacked from both sides with cubic crystalline layers.

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On the structure of amorphous germanium and silicon

Cited by 36 publications

References 31 publications

High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrateRb6.15Si46

High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrateRb6.15Si46

Computer program for radial distribution calculation from known bonding topologies

Topological Identification Criteria, Stability, and Relevance of Pentagonal Nanochannels in Amorphous Ice

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