Geometry and electronic structure of the Cu{sup 2+} polyhedra in trirutile-type compounds Zn(Mg){sub 1-x}Cu{sub x}Sb{sub 2}O{sub 6} and the dimorphism of CuSb{sub 2}O{sub 6}: A solid state and EPR study

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1997.7374· OSTI ID:576425

Giere, E O; Reinen, D ^[1]; Brahimi, A; Deiseroth, H J ^[2]

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1. Philipps-Universitaet Marburg (Germany)
2. Universitaet-GH Siegen (Germany)

Results from crystal structural analyses of CuSb{sub 2}O{sub 6} with the trirutile structure, which transforms from the {beta} phase (space group P2{sub 1}/n) to the {alpha}-phase (space group P4{sub 2}/nmn) at 380 K, are reported. While extensive twinning prevents the single crystal structure determination of the {beta} modification, the {alpha} phase reveals compressed CuO{sub 6}polyhedra with Cu-O spacings of 202.6 pm (2x) and 206.6 pm (4x). From the spectroscopic investigation (EPR, optical) of mixed crystals Zn(Mg){sub 1-x}Cu{sub x}Sb{sub 2}O{sub 6} with dependence on x and temperature it is deduced that the CuO{sub 6} polyhedra are compressed (spacings {approx} 197 pm (2x) and {approx} 208.5 pm (4x)) for x < 0.5 but transform to elongated entities at larger Cu{sup 2+} concentrations (spacings 200.4 pm (2x), 201.2 pm (2x), and 212.0 pm (2x) from neutron diffraction powder analysis (3)). Evidence for anisotropic {pi}-contributions to the Cu-O bond is presented. A detailed analysis of the ground state potential surface in terms of a vibronic Jahn-Teller coupling model in the presence of a host site strain is given for the two alternative CuO{sub 6} geometries. The Cu-O spacings in {alpha}-CuSb{sub 2}O{sub 6} are explained as resulting from those in the {beta} phase by a dynamic averaging process (201.2 pm (2x), 212.0 pm (2x) {yields} 206.6 pm (4x) above 380 K).

• OSTI ID: 576425
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 131; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

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