From Occupied Voids to Nanoprecipitates: Synthesis of Skutterudite Nanocomposites in situ

James Eilertsen, Yuri Surace, Sandor Balog, Leyre Sagarna, Gerda Rogl, Jelena Horky, Matthias Trottmann, Peter Rogl, M. A. Subramanian, Anke Weidenkaff

Nanocomposite thermoelectrics can exhibit both reduced thermal conductivity and enhanced electrical conductivity beyond single-phase materials; accordingly, they have become the new material paradigm to achieve viable thermoelectric efficiencies. New synthesis techniques are needed to further enhance their properties. A novel technique, designed to synthesize nanoprecipitates within a well-sintered single-phase polycrystalline matrix, is reported. The technique, attrition-enhanced nanocomposite synthesis (AENS), comprises three stages: (1) Synthesis of cage-like crystal structures with metastable interstitials, followed by (2) severe plastic deformation (SPD), and finally (3) rapid sintering with concomitant interstitial precipitation. The efficacy of this technique is demonstrated in this work. Filled cage-like skutterudite In0.2Co4Sb12 samples are synthesized and spark-plasma sintered. They are subjected to severe plastic deformation via high-pressure torsion, and finally sintered again via spark-plasma sintering in order to precipitate the metastable interstitials. X-ray diffraction, scanning-electron microscopy, and small-angle neutron scattering (SANS) of In0.2Co4Sb12 samples subjected to this procedure demonstrate that indium precipitates rapidly, and forms nano-sized In-based inclusions. In addition, the amount of precipitated indium, and the size and distribution of the nanoprecipitates are strongly influenced by the extent of plastic deformation. This technique can be employed to synthesize efficient thermoelectrics as well as materials with a number of applications requiring rapid synthesis of nano-sized precipitates.

Department of Physical Chemistry, Physics of Nanostructured Materials
External organisation(s)
Eidgenössische Materialprüfungs- und Forschungsanstalt, Université de Fribourg, Oregon State University, Universität Stuttgart
Zeitschrift für Anorganische und Allgemeine Chemie
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
104003 Inorganic chemistry, 104017 Physical chemistry, 103018 Materials physics
ASJC Scopus subject areas
Inorganic Chemistry
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