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

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

doi:10.1016/j.jssc.2012.11.025

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

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

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Abstract

The temperature dependence of anion ordering in the skutterudites CoGe_1.5Q_1.5 (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 CoGe_1.5S_1.5, anion ordering is preserved up to the melting point of 950 °C. However, rhombohedral CoGe_1.5Te_1.5 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 language	English
Pages (from-to)	525-531
Number of pages	7
Journal	Journal of Solid State Chemistry
Volume	198
DOIs	https://doi.org/10.1016/j.jssc.2012.11.025
Publication status	Published - 1 Feb 2013

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

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.",

author = "Andreas Kaltzoglou and Powell, {Anthony V.} and Knight, {Kevin S.} and Paz Vaqueiro",

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T1 - High-temperature order-disorder transitions in the skutterudites CoGe1.5Q1.5 (Q=S, Te)

AU - Kaltzoglou, Andreas

AU - Powell, Anthony V.

AU - Knight, Kevin S.

AU - Vaqueiro, Paz

PY - 2013/2/1

Y1 - 2013/2/1

N2 - 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.

AB - 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.

U2 - 10.1016/j.jssc.2012.11.025

DO - 10.1016/j.jssc.2012.11.025

M3 - Article

SN - 0022-4596

VL - 198

SP - 525

EP - 531

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

ER -

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

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