Using crystallographic shear to reduce lattice thermal conductivity: high temperature thermoelectric characterization of the spark plasma sintered Magnéli phases WO2.90 and WO2.722

Engineering of nanoscale structures is a requisite for controlling the electrical and thermal transport in solids, in particular for thermoelectric applications that require a conflicting combination of low thermal conductivity and low electrical resistivity. We report the thermoelectric properties...

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Published inPhysical chemistry chemical physics : PCCP Vol. 15; no. 37; pp. 15399 - 1543
Main Authors Kieslich, Gregor, Veremchuk, Igor, Antonyshyn, Iryna, Zeier, Wolfgang G, Birkel, Christina S, Weldert, Kai, Heinrich, Christophe P, Visnow, Eduard, Panthöfer, Martin, Burkhardt, Ulrich, Grin, Yuri, Tremel, Wolfgang
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 07.10.2013
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Summary:Engineering of nanoscale structures is a requisite for controlling the electrical and thermal transport in solids, in particular for thermoelectric applications that require a conflicting combination of low thermal conductivity and low electrical resistivity. We report the thermoelectric properties of spark plasma sintered Magnéli phases WO 2.90 and WO 2.722 . The crystallographic shear planes, which are a typical feature of the crystal structures of Magnéli-type metal oxides, lead to a remarkably low thermal conductivity for WO 2.90 . The figures of merit (ZT = 0.13 at 1100 K for WO 2.90 and 0.07 at 1100 K for WO 2.722 ) are relatively high for tungsten-oxygen compounds and metal oxides in general. The electrical resistivity of WO 2.722 shows a metallic behaviour with temperature, while WO 2.90 has the characteristics of a heavily doped semiconductor. The low thermopower of 80 μV K −1 at 1100 K for WO 2.90 is attributed to its high charge carrier concentration. The enhanced thermoelectric performance for WO 2.90 compared to WO 2.722 originates from its much lower thermal conductivity, due to the presence of crystallographic shear and dislocations in the crystal structure. Our study is a proof of principle for the development of efficient and low-cost thermoelectric materials based on the use of intrinsically nanostructured materials rather than artificially structured layered systems to reduce lattice thermal conductivity. Engineering of nanoscale structures is a requisite for controlling the electrical and thermal transport in solids, in particular for thermoelectric applications.
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ISSN:1463-9076
1463-9084
DOI:10.1039/c3cp52361f