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Structural Effects on the Electronic Properties of TlCu7–δS4 Investigated by Diffraction-Resistance Measurements

Authors

  • T. Erinc Engin,

    1. Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK
    2. The ISIS Facility, STFC, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 OQX, UK
    3. Presently at:, Tubitak Ume, PO Box 54, 41470 Gebze Kocaeli, Turkey
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  • Steve Hull,

    1. The ISIS Facility, STFC, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 OQX, UK
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  • Anthony V. Powell

    Corresponding author
    1. Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK
    • Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK, Fax: +44-131-451-3180
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  • Supporting Information for this article is available on the WWW under http://dx.doi.org/10.1002/zaac.201200296 or from the author.

Abstract

The design and construction of a specialised sample cell for the simultaneous investigation of electron-transport and structural properties by powder neutron diffraction in the temperature range1.5 ≤ T /K ≤ 300 is described. This cell has been used to investigate the structural origin of anomalies in the transport properties of the pseudo-one-dimensional ternary sulfide TlCu7–δS4 (δ = 0.15). The data reveal an anomaly in ρ(T) observed at 255 K, which is associated with a phase change involving a change in symmetry from I4/m to P4/n on cooling. This corresponds to a doubling of the crystallographic c axis and is evidenced by the splitting of a strong reflection at d = 2.28 Å and the appearance of additional peaks in the low-temperature diffraction data. A lower temperature ρ(T) anomaly at 205 K is related to subtle structural distortions involving chains of edge-shared Cu4 tetrahedra.

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