Journal of Materials Research


Transport properties and microstructure of indium-added cobalt–antimony-based skutterudites

Andreas Sesselmanna1 c1, Titas Dasguptaa1, Klemens Kelma1, Eckhard Müllera1, Susanne Perlta2 and Sebastian Zastrowa3

a1 Institute of Materials Research, German Aerospace Center (DLR), D-51170 Köln, Germany

a2 Leibniz-Institute for Surface Modification, D-04318 Leipzig, Germany

a3 Institute of Applied Physics, University of Hamburg, D-20355 Hamburg, Germany


Indium has attracted much attention as a beneficial addition to cobalt–antimony-based skutterudites as a result of good thermoelectric performance. In this study, as-cast InxCo4Sb12 with x = 0.05, 0.2 were examined using x-ray diffraction analysis and scanning electron microscopy. For x = 0.2 we found, besides the skutterudite main phase, nanometer-sized regions of secondary phases distributed along the grain boundaries, which exhibit substructures. As-cast material with x = 0.05 does not show visible precipitates. We further observed that changing one of the heat treatment parameters of In0.2Co4Sb12 has a major effect on the microstructure and shape of the precipitates, but minor influence on the skutterudite matrix composition. Energy dispersive x-ray spectroscopy analysis by transmission electron microscopy) reveals that indium is to a large extent distributed into the skutterudite structure. Measurements of short-term sintered material confirm that the addition of indium and particularly the modification of the synthesis parameter entails to an enhanced ZT.

(Received January 17 2011)

(Accepted March 17 2011)

Key Words:

  • Thermoelectricity;
  • Microstructure;
  • Scanning electron microscopy


c1 Address all correspondence to this author. e-mail: