Theoretical modeling of Te doped CoSb3

L. Bertini1, K. Billquist2, M. Christensen3, C. Gatti1, L. Holmgren4, B. Iversen3, E. Mueller5, M. Muhammed2, G. Noriega6, A. Palmqvist7, D. Platzek5, D.M. Rowe8, A. Saramat7,

C. Stiewe5, M. Toprak2, S.G. Williams8, Y. Zhang2

1Istituto di Scienze e Tecnologie Molecolari (ISTM), Via Camillo Golgi 19, 20133 Milano, Italy

2Royal Institute of Technology, Materials Chemistry Division, SE-10044 Stockholm, Sweden

3University of Aarhus, Department of Chemistry, DK-8000 C Aarhus, Denmark

4LEGELAB, SE-451 44 Uddevalla, Sweden

5German Aerospace Center (DLR), Institute of Materials Research, D-51170 Cologne, Germany

6CIDETE Ingenieros SL, E-08800 Vilanova (Barcelona), Spain

7Chalmers University of Technology, Dept. Applied Surface Chemistry, Goteborg, Sweden

8NEDO Laboratory for Thermoelectric Engineering (NEDO), Cardiff, UK

The electronic structure of the Te doped CoSb3 skutterudite has been investigated by means of fully periodic density functional theory calculations. Knowledge of the structure of a material is a fundamental prerequisite for understanding its properties, Te substituted for Sb (Co4Sb11Te) and Te fully filled (TeCo4Sb12) cobalt skutterudite are both considered in order to understand where Te atoms are sitting. Based on geometrical and thermochemistry considerations, the Te filled system is ruled out.

The Quantum Theory of Atom in Molecules has been used to estimate the extent of the charge transfer among Co, Sb and Te atoms. The density of states shows that Te substitution for Sb yields a conduction state material with the Fermi level lying in the conduction band zone of the unmodified CoSb3.

The Seebeck coefficient and the electrical conductivity s are calculated using semiclassical Boltzmann monoelectronic transport theory in the approximation of a constant relaxation time. The computational results are compared to the experimental thermoelectric characterization of nanostructured Te doped CoSb3 samples.