Structure Refinement of AuSn<sub>2</sub>

Rodewald, Ute Ch.; Hoffmann, Rolf‐Dieter; Wu, Zhiyun; Pöttgen, Rainer

doi:10.1515/znb-2006-0121

Cited by 14 publications

(2 citation statements)

References 4 publications

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“…It should be noted that the structure is isopuntal with the brookite polymorph of TiO 2 , but whereas the Ti atoms of brookite have six oxygen neighbours at 1.863-2.052 Å (Meagher and Lager, 1979), the lone-pair stereoactivity of Te 4+ distorts the coordination octahedron to give only four neighbours in the range 1.88-2.20 Å, an additional neighbour within the layer at 2.64 Å, and a weak Te-O bond across the interlayer gap at 3.07 Å. A variant of the structure with additional anionanion bonding occurs for the pararammelsbergite form of NiAs 2 (Fleet, 1972) and intermetallic compounds such as AuSn 2 (Rodewald et al, 2006 1300 Te polyhedra link to form layers of 6-rings, topologically equivalent to the silicate sheets of the 'micas' (Fig. 11g).…”

Section: Trimeric Tementioning

confidence: 99%

A review of the structural architecture of tellurium oxycompounds

2016

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Relative to its extremely low abundance in the Earth's crust, tellurium is the most mineralogically diverse chemical element, with over 160 mineral species known that contain essential Te, many of them with unique crystal structures. We review the crystal structures of 703 tellurium oxysalts for which good refinements exist, including 55 that are known to occur as minerals. The dataset is restricted to compounds where oxygen is the only ligand that is strongly bound to Te, but most of the Periodic 4+ cations display one-sided 3-, 4-or 5-coordination by oxygen (with rare examples of coordination numbers 2 and 6). For both valence states of Te, examples are known of Te m O n complexes which are monomeric (m = 1; neso), noncyclic finite oligomers (soro), rings (cyclo), infinite chains (ino), layers ( phyllo) and frameworks (tecto tellurates). There is a clear analogy to the polymerization classes that are known for silicate anions, but the behaviour of Te is much richer than that of Si for several reasons: (1) the existence of two cationic valence states for Te; (2) the occurrence of multiple coordination numbers; (3) the possibility of edge-sharing by TeO n polyhedra; (4) the possibility for oxygen ligands to be 3-coordinated by Te; and (5) the occurrence of Te m O n polymers that are cationic, as well as neutral or anionic. While most compounds contain only one or two symmetrically distinct types of Te atom, Pauling's Fifth Rule is frequently violated, and stoichiometrically simple compounds such as CaTeO 3 can have polymorphs with up to 18 distinct Te sites. There is a tendency for local symmetry features such as the threefold axis of a TeO 6 octahedron or the acentric symmetry of a Te 4+ O n polyhedron to be inherited by the host structure; the latter in particular can lead to useful physical properties such as nonlinear optical behaviour. We develop for the first time a hierarchical taxonomy of Te-oxysalt structures, based upon (1) valence state of Te; (2) polymerization state of Te m O n complexes; (3) polymerization state of larger strongly-bound structural units that include non-Te cations. Structures are readily located and compared within this classification.

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Section: Trimeric Tementioning

confidence: 99%

A review of the structural architecture of tellurium oxycompounds

2016

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“…We also found two other structures with energies close to the CoSb 2 structure: Mo 2 N, [63] which is another structure constructed by removing atoms from a supercell of NaCl, and AuSn 2 . [64] Neither structure is a candidate for the ground state of WN 2 . Parameters of the minimum energy structures for all of these phases are given in the supplementary material.…”

Section: Predicted Wn2 Structuresmentioning

confidence: 99%

Finding the stable structures ofN1−xWxwith anab initiohigh-throughput approach

et al. 2015

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Using density functional theory calculations, many researchers have predicted that various tungsten-nitride compounds WNx(x > 1) will be "ultra-incompressible" or "superhard", i.e. as hard as or harder than diamond. These compounds are predicted to have large bulk and shear moduli, (> 200 GPa) and to be elastically and vibrationally stable.Compounds with such desirable properties must be energetically stable against decomposition into other compounds. This stability can only be found after the determination of the convex hull for WxN1−x lines which connect the lowest enthalpy structures as a function of composition. The phase diagram of the W-N structure is uncertain, both experimentally and computationally. Complex van der Waals forces play a significant role in determining the structure of solid N2.Here we use high-throughput calculations to map out the convex hull and other low energy structures for the W-N system. We find that the ground state of the system is the NbO structure, and that the WN2 structures found by Wang et al. are also stable when van der Waals forces are neglected. Other proposed structures are above the convex hull of the W-N system. We show how the choice of density functional influences the shape of the curve and the structures that form the hull. In nitrogen-rich compounds, the choice of functional can dramatically change the structural parameters and mechanical behavior. Using any of the functionals, the bulk and shear moduli of the NbO phase are comparable to the WNx compounds that have been claimed to be ultra-incompressible or superhard.

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Knüpfung von Thiostannat‐Sn‐Sn‐Bindungen in Lösung: In‐situ‐Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSn^IV)₂(μ‐S)₂}₃Sn^III₂S₆]

et al. 2009

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Im Tageslicht kondensiert das Doppeldecker‐artige Thiostannat [(RSnIV)4S6] (1, R=CMe2CH2COMe) zum gemischtvalenten Komplex [{(RSnIV)2(μ‐S)2}3SnIII2S6] (2, siehe Bild), der (formal) SnIII‐ neben SnIV‐Zentren enthält, wie durch Mößbauer‐Spektroskopie und DFT‐Rechnungen bestätigt wurde. 2 weist sechs funktionelle CO‐Gruppen für weitere Reaktionen an der Ligandenhülle auf, und die Bildung scheint über einen komplizierten konzertierten Mechanismus zu verlaufen.

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Structure Refinement of AuSn₂

Cited by 14 publications

References 4 publications

A review of the structural architecture of tellurium oxycompounds

A review of the structural architecture of tellurium oxycompounds

Finding the stable structures ofN1−xWxwith anab initiohigh-throughput approach

Knüpfung von Thiostannat‐Sn‐Sn‐Bindungen in Lösung: In‐situ‐Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSn^IV)₂(μ‐S)₂}₃Sn^III₂S₆]

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Structure Refinement of AuSn2

Cited by 14 publications

References 4 publications

A review of the structural architecture of tellurium oxycompounds

A review of the structural architecture of tellurium oxycompounds

Finding the stable structures ofN1−xWxwith anab initiohigh-throughput approach

Knüpfung von Thiostannat‐Sn‐Sn‐Bindungen in Lösung: In‐situ‐Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSnIV)2(μ‐S)2}3SnIII2S6]

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Structure Refinement of AuSn₂

Knüpfung von Thiostannat‐Sn‐Sn‐Bindungen in Lösung: In‐situ‐Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSn^IV)₂(μ‐S)₂}₃Sn^III₂S₆]