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Title: High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te)

Abstract

The temperature dependence of anion ordering in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te) has been investigated by powder neutron diffraction. Both materials adopt a rhombohedral structure at room temperature (space group R3{sup Macron} ) in which the anions are ordered trans to each other within Ge{sub 2}Q{sub 2} rings. In CoGe{sub 1.5}S{sub 1.5}, anion ordering is preserved up to the melting point of 950 Degree-Sign C. However, rhombohedral CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C involving a change to cubic symmetry (space group Im3{sup Macron }). In the high-temperature modification, there is a statistical distribution of anions over the available sites within the Ge{sub 2}Te{sub 2} rings. The structural transition involves a reduction in the degree of distortion of the Ge{sub 2}Te{sub 2} rings which progressively transform from a rhombus to a rectangular shape. The effect of this transition on the thermoelectric properties has been investigated. - Graphical abstract: Powder neutron diffraction reveals that the skutterudite CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C, involving the disordering of the anions within the Ge{sub 2}Te{sub 2} rings. Highlights: Black-Right-Pointing-Pointer CoGe{sub 1.5}S{sub 1.5} retains an ordered skutterudite structure up to 950 Degree-Sign C. Black-Right-Pointing-Pointermore » CoGe{sub 1.5}Te{sub 1.5} undergoes an order-disorder phase transition at 610 Degree-Sign C. Black-Right-Pointing-Pointer Below 610 Degree-Sign C, anions are arranged trans to each other within Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer Above 610 Degree-Sign C, anions are statistically distributed within the Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer The effect of the phase transition on the thermal conductivity is discussed.« less

Authors:
;  [1];  [2];  [1]
  1. Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery (CAESAR), Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)
  2. ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0OX (United Kingdom)
Publication Date:
OSTI Identifier:
22150061
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 198; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANIONS; DISTRIBUTION; MELTING POINTS; NEUTRON DIFFRACTION; ORDER-DISORDER TRANSFORMATIONS; POWDERS; RINGS; SPACE GROUPS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; THERMAL CONDUCTIVITY; THERMOELECTRIC PROPERTIES; TRIGONAL LATTICES

Citation Formats

Kaltzoglou, Andreas, Powell, Anthony V., Knight, Kevin S., and Vaqueiro, Paz. High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te). United States: N. p., 2013. Web. doi:10.1016/J.JSSC.2012.11.025.
Kaltzoglou, Andreas, Powell, Anthony V., Knight, Kevin S., & Vaqueiro, Paz. High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te). United States. https://doi.org/10.1016/J.JSSC.2012.11.025
Kaltzoglou, Andreas, Powell, Anthony V., Knight, Kevin S., and Vaqueiro, Paz. 2013. "High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te)". United States. https://doi.org/10.1016/J.JSSC.2012.11.025.
@article{osti_22150061,
title = {High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te)},
author = {Kaltzoglou, Andreas and Powell, Anthony V. and Knight, Kevin S. and Vaqueiro, Paz},
abstractNote = {The temperature dependence of anion ordering in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te) has been investigated by powder neutron diffraction. Both materials adopt a rhombohedral structure at room temperature (space group R3{sup Macron} ) in which the anions are ordered trans to each other within Ge{sub 2}Q{sub 2} rings. In CoGe{sub 1.5}S{sub 1.5}, anion ordering is preserved up to the melting point of 950 Degree-Sign C. However, rhombohedral CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C involving a change to cubic symmetry (space group Im3{sup Macron }). In the high-temperature modification, there is a statistical distribution of anions over the available sites within the Ge{sub 2}Te{sub 2} rings. The structural transition involves a reduction in the degree of distortion of the Ge{sub 2}Te{sub 2} rings which progressively transform from a rhombus to a rectangular shape. The effect of this transition on the thermoelectric properties has been investigated. - Graphical abstract: Powder neutron diffraction reveals that the skutterudite CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C, involving the disordering of the anions within the Ge{sub 2}Te{sub 2} rings. Highlights: Black-Right-Pointing-Pointer CoGe{sub 1.5}S{sub 1.5} retains an ordered skutterudite structure up to 950 Degree-Sign C. Black-Right-Pointing-Pointer CoGe{sub 1.5}Te{sub 1.5} undergoes an order-disorder phase transition at 610 Degree-Sign C. Black-Right-Pointing-Pointer Below 610 Degree-Sign C, anions are arranged trans to each other within Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer Above 610 Degree-Sign C, anions are statistically distributed within the Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer The effect of the phase transition on the thermal conductivity is discussed.},
doi = {10.1016/J.JSSC.2012.11.025},
url = {https://www.osti.gov/biblio/22150061}, journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = ,
volume = 198,
place = {United States},
year = {Fri Feb 15 00:00:00 EST 2013},
month = {Fri Feb 15 00:00:00 EST 2013}
}