The crystal structure of Ta₂S

Abstract

The crystal structure of ditantalum sulfide, Ta2S, has been determined from single-crystal X-ray diffraction data. The compound crystallizes in the orthorhombic system, space group Pbcm, with unitcell dimensions: a=7"379, b=5"574, and c= 15.19 A. The unit cell contains 12 formula units. Refinement of the structure was performed by a least-squares treatment of the positional parameters and the temperature factor coefficients. The Ta/S structure is fundamentally different from other known metalrich chalconide structures. The structure can be viewed as chains of body-centered pentagonal antiprisms of tantalum atoms sharing faces in one direction and interconnected via sulfur atoms in the other two directions.

The crystal structure of Zr9S2

“…This distance is conside]ably less than distances found in the h. c. p. form of zirconium metal (3.18 and 3-23 •) and is comparable to that found in the high pressure oophase structure of the metal (2.91 A) when quenched to one atmosphere (Jamieson, 1963). Short intermetallic distances have also been found in other zirconium-rich compounds, such as the o--like Zr4A13 (2.70 A) and the D,8,-type ZrsA13 (2.70/~,) as discussed by Edshammar (1962), and other metal-rich sulfides, such as Ta6S (Franzen & Smeggil, 1970), TazS (Franzen & Smeggil, 1969), and the two V3S phases mentioned earlier. In all these cases, the short distances always appear between the apical and the central atoms of Kasper polyhedra.…”

Ta3S2−xSex, Partial Substitution of Selenium for Sulfur into a Tantalum-Rich Sulfide

“…Whereas the structure of Ta2S (Franzen & Smeggil, 1969) results from the interpenetration of centred Tal3 icosahedra along a Ta3S2] and longer interlayer Ch--Ta contacts. The Ch2 position is 12.1 (9)% occupied by Se.…”

AuTa5S: A Cubic Rod Packing of Condensed (Au, Ta)13Icosahedra Interwoven with a Three-Dimensional Framework of Corner-Connected STa6Octahedra

“…Prominent representatives are the Frank-Kasper phases (1-3), many of which consist of transition metals or additionally contain aluminum or silicon as a main-group element. However, there are also a small number of phases among metal-rich pnictides and chalcogenides forming structures composed of metalcentered M icosahedra, e.g., Pd P (4) and several tantalum-rich sulfides (5)(6)(7)(8)(9)(10).…”