Condensed rare-earth metal-rich tellurides. Extension of layered Sc6PdTe2-type compounds to yttrium and lutetium analogues and to Y7Te2, the limiting binary member

Six isotypic R(6)ZTe(2) phases have been synthesized in Ta at elevated temperatures and characterized by single crystal X-ray refinements for R = Y, Z = Rh, Pd, Ag, Y and for R Lu, Z = Cu, Ag. All crystallize in the Sc6PdTe2-type structure, Pnma, Z = 4, a similar to 21.5 angstrom, b similar to 4.1 angstrom, c similar to 11.4 angstrom. The results can be viewed as the replacement of Te3 atoms in the parent isotypic Sc2Te (or in the hypothetical Y2Te or Lu2Te analogues) by the above the Z, the Y example giving the new binary phase Y7Te2. The shorter (and stronger) metal-metal bonds concentrate in the region of metal (Z, Y) substitution, as revealed by larger integrated crystal orbital Hamilton population (ICOHP) values derived from linear muffin-tin-orbital (LMTO) calculations. Partial densities-of-states data for Y7Te2 reflect a similar behavior. Individual R-R bond distances are seen to deviate appreciably from the more fundamental overlap population measures for each. (C) 2007 Elsevier Inc. All rights reserved.