Thermoelectric Properties of In x Co 4-y Ni y Sb 12 Skutterudite Compounds
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1044-U05-06
Thermoelectric Properties of InxCo4-yNiySb12 Skutterudite Compounds Veronique Da Ros1, Juliusz Leszczynski1, Bertrand Lenoir1, Anne Dauscher1, Christophe Candolfi1, Philippe Masschelein1, Christine Bellouard2, Christian Stiewe3, Eckard Mueller3, and Jiri Hejtmanek4 1 Laboratoire de Physique des Materiaux, Ecole Nationale Superieure des Mines de Nancy, Parc de Saurupt, CS 14234, Nancy, 54042, France 2 Laboratoire de Physique des Materiaux, Universite Henri Poincare - Nancy I, BP 239, Vandoeuvre les Nancy, 54506, France 3 Institute of Materials Research, German Aerospace Center DLR, Linder Hoehe, Geb. 51, Köln, D-51147, Germany 4 Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, Praha 6Stresovice, 10162 53, Czech Republic ABSTRACT The preparation of partially filled n-type InxCo4Sb12 skutterudite compounds has been recently reported. The results were particularly promising, the materials exhibiting a ZT value far higher than one at moderated temperature. In this paper, we propose to investigate another way to tune the electrical and thermal properties by substituting Co atoms by Ni atoms in InxCo4Sb12. InxCo4-yNiySb12 polycrystalline samples have been prepared by a conventional metallurgical route. Structural analyses have been carried out by X-ray diffraction. The chemical composition and micro-homogeneity have been checked by electron probe microanalysis. Measurements of the electrical resistivity, thermoelectric power and thermal conductivity have been performed between 300 and 800 K. The influence of the presence of Ni on the thermoelectric properties of InxCo4Sb12 compounds is presented and discussed. INTRODUCTION The CoSb3-based filled skutterudites continue to attract a lot of attention as potential thermoelectric materials for elevated temperature applications. Particular interest is focused on ntype skutterudites as their thermoelectric properties are still not as good as in p-type skutterudites. A variety of approaches were applied to improve skutterudite thermoelectric properties involving partial filling of the structural voids, formation of CoSb3 isoelectronic solid solutions and doping by proper substitution at the metal or pnicogen sites. Among all these diverse methods void filling was found to be the most efficient. The presence of a filler element leads to a strong reduction of the thermal conductivity as compared to the parent composition and also affects its electrical properties by introducing additional electrons and modifying band structure yielding high power factors. The best improvement of the thermoelectric properties was achieved by partial filling with rare earth elements (Yb, Eu [1,2]) and alkaline metals (Ca, Ba[36]) and ZT values exceeding 1 at T ≥600K were reported. In case of alkaline filling elements it was shown that further improvement of thermoelectric figure of merit can be obtained by careful tuning of carrier concentration accomplished by Ni doping. Quite recently He et al. [7] published very promising results of thermoelectric perf
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