Ag12Te6S: A Contribution to Open Problems in the Crystal Chemistry of Complex Non-Metallic Filled Frank-Kasper Phases

The air stable gray‐metallic Ag12Te6S is a substitution variant of synthetic Ag5−xTe3 (mineral name: stutzite, range of x controversial) crystallizing in the space group $P{\bar 6}$ (Z = 3) with lattice parameters a = 13.413(2) Å, c = 8.452(2) Å. All non‐metal atoms in this complex solid are topolog...

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Bibliographic Details
Published in:Zeitschrift für anorganische und allgemeine Chemie (1950) 2005-05, Vol.631 (6-7), p.1233-1236
Main Authors: Mikus, H., Deiseroth, H. J.
Format: Article
Language:English
Subjects:
Frank Kasper phase
Silver telluride
Stutzite
Zr4Al3
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Summary:The air stable gray‐metallic Ag12Te6S is a substitution variant of synthetic Ag5−xTe3 (mineral name: stutzite, range of x controversial) crystallizing in the space group $P{\bar 6}$ (Z = 3) with lattice parameters a = 13.413(2) Å, c = 8.452(2) Å. All non‐metal atoms in this complex solid are topologically arranged like Zr and Al atoms in the Frank‐Kasper phase Zr4Al3 forming a system of interpenetrating Frank‐Kasper polyhedra with coordination numbers 12, 14 and 15. Symmetry relations between stutzite, Zr4Al3 and the title compound are presented. The interpenetration of Frank‐Kasper polyhedra results in a complex three‐dimensional network of distorted tetrahedra intimately connected by common corners, edges, and faces (tetrahedral or topological close packing). A specific disorder problem which complicates the compositional and structural characterization of stutzite considerably is not present in the title compound. Whereas stutzite contains single Te2−, (Te2)2−(ordered), and additional (Te2)2− sharing a poorly resolved number of common crystallographic positions with further Te2−, in the title compound ordered Te2−, (Te2)2−, and S2− are found only, not leaving any ambiguity for the number of charge compensating Ag+ ions. Except of a new silver position in close vicinity to the S2−, the distribution of the strongly disordered Ag+ in the title compound is only slightly different from that in stutzite and is not further discussed in this paper. Literature reports concerning a c‐axis doubling cannot be confirmed neither for stutzite nor for the title compound.
ISSN:0044-2313
1521-3749
DOI:10.1002/zaac.200500018