The crystal structures of NbT₂and TaTe₂

Abstract

The crystal structures of the isostructural compounds, NbTe2 and TaTe2, have been solved by Patterson methods. Single crystals were grown by vapor transport methods. Cell dimensions, as measured on precession photographs, are for NbTe2, a= 19.39, b= 3.642, c=9.375 •, r= 134°35 ', and for TaTe2, a= 19-31, b= 3-651, c=9-377 A, r= 134 ° 13'. Both compounds belong to the space group C2/m.Refinement of the hOl intensities by least-squares methods gave R values of 13 Yo and 10 Vo for NbTe2 and TaTe2 respectively. The compounds are layer structures with distorted octahedral coordination of the metal atoms by tellurium atoms. The distortion is a response to a pattern of metal-metal bonding in which the metals are grouped into triple rows parallel to the y axis. This grouping puts two-thirds of the metal atoms in distorted octahedra and one-third in relatively regular octahedra.

Fermi-surface-induced lattice distortion inNbTe2

“…The DFPT phonon bandstructure for the relaxed trigonal NbTe 2 structure obtained by diagonalization of the dynamical matrix along high symmetry lines is shown in Fig. 7 [3] for the trigonal structure by less then 1 %, following the general trend observed for LDA results [52]. The LDA equilibrium value for z red = 0.274 is also in good agreement with the derived averaged value z red = 0.277 (see Appendix ).…”

“…The distortion already observed at room temperature in NbTe 2 and the isostructural TaTe 2 suggests the action of a single-axis CDW. The structure [3] is a monoclinically deformed version of the trigonal 1T polytype, in which the transition metal sits in octahedrally coordinated sites between the chalcogen atoms (see Appendix for structural details). The metal atoms are displaced from the center of the coordination unit and the chalcogen layers form zig-zag chains to accomodate these shifts (see Fig.…”

Anisotropic magneto-transport and magnetic properties of low-temperature phase of TaTe 2

“…12), Z=6, a=19.31 Å, b=3.651 Å, c=9.377 Å, β=134.22°) 6 . In TaTe2, each Ta atom is surrounded by six Te atoms, resulting in a distorted TaTe2 octahedron (left inset in Fig.…”

Tris(tetraphenylphosphonium) Decatelluriumtantalide Dimethylformamide (1/1), a Tetraphenylphosphonium Salt of TaTe103−

“…To the best of our knowledge, this is the only isolated tantalum-tellurium anion that has been structurally characterized, but the TamTe distances fall within the ranges of known tantalum tellurides, TaTe2 (Brown, 1966) and TaTe4 (Bjerkelund & Kjekshus, 1964), and are considerably longer than the value of 2.568 (1),4, found for a terminal TamTe bond in [TeTa{(Me3SiNCH2CH2)3N}] (Christou & Arnold, 1993). The TemTe distances are grouped into two significantly different ranges, i.e.…”