High-temperature order-disorder transitions in the skutterudites CoGe1.5Q1.5 (Q=S, Te)

Andreas Kaltzoglou, Anthony V. Powell, Kevin S. Knight, Paz Vaqueiro

Research output: Contribution to journalArticle

3 Citations (Scopus)
207 Downloads (Pure)

Abstract

The temperature dependence of anion ordering in the skutterudites CoGe1.5Q1.5 (Q=S, Te) has been investigated by powder neutron diffraction. Both materials adopt a rhombohedral structure at room temperature (space group R-3) in which the anions are ordered trans to each other within Ge2Q2 rings. In CoGe1.5S1.5, anion ordering is preserved up to the melting point of 950 °C. However, rhombohedral CoGe1.5Te1.5 undergoes a phase transition at 610 °C involving a change to cubic symmetry (space group Im-3). In the high-temperature modification, there is a statistical distribution of anions over the available sites within the Ge2Te2 rings. The structural transition involves a reduction in the degree of distortion of the Ge2Te2 rings which progressively transform from a rhombus to a rectangular shape. The effect of this transition on the thermoelectric properties has been investigated.

Original languageEnglish
Pages (from-to)525-531
Number of pages7
JournalJournal of Solid State Chemistry
Volume198
DOIs
Publication statusPublished - 1 Feb 2013

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