12020-39-2Relevant articles and documents
Novel condensation of Au-centered trigonal prisms in rare-earth-metal-rich tellurides: Er7Au2Te2 and Lu7Au 2Te2
Gupta, Shalabh,Corbett, John D.
, p. 6074 - 6079 (2010)
A new monoclinic structure occurs for Er7Au2Te 2 according to X-ray diffraction analysis of single crystals grown at 1200 °C: C2/m, Z = 4, a = 17.8310(9) A, b = 3.9819(5) A, c = 16.9089(9) A, β = 104.361(4)°. The isostructural Lu 7Au2Te2 also exists according to X-ray powder pattern means, a = 17.536(4) A, b = 3.9719(4) A, c = 16.695(2) A, β = 104.33(1)°. The structure contains zigzag chains of condensed, Au-centered tricapped trigonal prisms (TCTP) of Er along c that also share basal faces along b to generate puckered sheets. Further bi-face-capping Er atoms between these generate the three dimensional network along a, with tellurium in cavities outlined by augmented trigonal prismatic Er polyhedra. Bonding analysis via LMTO-DFT methods reveal very significant Er-Au bonding interactions, as quantified by their energy-weighted Hamilton overlap populations (-ICOHP), ～49% of the total for all interactions. These and similar Er-Te contributions sharply contrast with the small Er-Er population, only ～14% of the total in spite of the high proportion of Er-Er contacts. The strong polar bonding of Er to the electronegative Au and Te leaves Er relatively oxidized, with many of its 5d states falling above the Fermi level and empty. The contradiction with customary representations of structures that highlight rare-earth metal clusters is manifest. The large Er-Au Hamilton overlap population is in accord with the strong bonding between early and late transition metals first noted by Brewer in 1973. The relationship of this structure to the more distorted orthorhombic (Imm2) structure type of neighboring Dy7Ir2Te2 is considered.
Rare-earth-rich tellurides: Gd4NiTe2 and Er 5M2Te2 (M=Co, Ni)
Magliocchi, Carmela,Meng, Fanqin,Hughbanks, Timothy
, p. 3896 - 3902 (2004)
Three new rare earth metal-rich compounds, Gd4NiTe2, and Er5M2Te2 (M=Ni, Co), were synthesized in direct reactions using R, R3M, and R2Te3 (R=Gd, Er; M=Co, Ni) and single-crystal structures were determined. Gd 4NiTe2 is orthorhombic and crystallizes in space group Pnma with four formula units per cell. Lattice parameters at 110(2) K are a=15.548(9), b=4.113(2), c=11.7521(15)A. Er5Ni 2Te2 and Er5Co2Te2 are isostructural and crystallize in the orthorhombic space group Cmcm with two formula units per cell. Lattice parameters at 110(2) K are a=3.934(1), b=14.811(4), c=14.709(4)A, and a=3.898(1), b=14.920(3), c=14.889(3)A, respectively. Metal-metal bonding correlations were analyzed using the empirical Pauling bond order concept. Slightly-off [010] projection of the Gd4NiTe2 structure, featuring Gd6Ni 2 chains that exemplify an increasingly common structural motif in reduced ternary tellurides of the rare-earth metals.
Er17Ru6Te3: A highly condensed metal-rich ternary telluride
Mehta, Akash,Corbett, John D.
, p. 871 - 877 (2008)
Er17Ru6Te3 is obtained from high-temperature solid-state reactions in tantalum ampoules. The structure according to single-crystal X-ray diffraction is monoclinic, C2/m (no. 12), Z=4, a=40.185(8) A, b=3.9969(8) A, c=16.037(3) A, β=95.12(3)°, V=2565.5(9) A3. The condensed structure consists of a complex intermetallic network of intergrown sheets of edge-sharing tetrakaidecahedra (tricapped trigonal prisms, TCTP), and pairs of rectangular-face-sharing bicapped trigonal prisms (BCTP) built of erbium and centered by ruthenium. This array also contains isolated columns of TCTP erbium normal to these sheets that contain tellurium. Basal face sharing of all Er polyhedra along the short b-axis gives rise to the three-dimensional network. Synthesis and the crystal structure of the compound are discussed.
