Cu(Cu0.44Cr4.56)Ge2O12: a close-packed oxide with CuO4 tetrahedra.

Department of Material Science, Division of Mineralogy, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria.
Acta Crystallographica Section C Crystal Structure Communications (Impact Factor: 0.54). 05/2007; 63(Pt 4):i21-4. DOI: 10.1107/S0108270107005355
Source: PubMed

ABSTRACT The structure of copper(I,II) pentachromium(III) germanate, Cu(Cu(0.44)Cr(4.56))Ge(2)O(12), contains one Cu position (m2m), one Ge position (m) and three Cr positions (2/m, m and 2). The close-packed structure is described in terms of slabs of edge-sharing Cr(3+)O(6) octahedra and isolated CuO(4) and GeO(4) tetrahedra. These slabs are aligned parallel to the bc plane and are separated from each other by GeO(4) tetrahedra along a. The tetrahedral coordination observed for the Cu(+)/Cu(2+) ions represents an unusual feature of the structure. The Cr-O and Cu-O bond lengths are compared with literature data.

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