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Thermoelectric properties of indium filled and germanium doped Co4Sb12 skutterudites

Mallik, Ramesh Chandra and Mueller, Eckhard and Kim, Il-Ho (2012) Thermoelectric properties of indium filled and germanium doped Co4Sb12 skutterudites. In: Journal of Applied Physics, 111 (2).

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In-filled and Ge-doped Co4Sb12 skutterudites materials were synthesized by an induction melting process which was followed by annealing at 650 degrees C for 7 days. A structural, compositional, and morphological study was carried out by X-ray diffraction (XRD), electron probe micro analysis (EPMA), and scanning electron microscopy (SEM). The formation of a single skutterudite phase (delta-CoSb3) was confirmed by XRD and the composition of all the samples was verified by EPMA. The homogeneity and morphology of the samples was observed by potential Seebeck microprobe (PSM) and SEM, respectively. The PSM result confirmed the inhomogeneity of the samples. The temperature dependence of the Seebeck coefficient, electrical conductivity, and thermal conductivity were measured in the temperature range of 300-650 K. The samples of In0.16Co4Sb12-xGex (x = 0.05, 0.1, and 0.2) show a negative Seebeck coefficient confirming an n-type conductivity and the In0.16Co4Sb11.7Ge0.3 sample shows a positive Seebeck coefficient confirming a p-type conductivity. There was a change in the Seebeck coefficient from an n-type to a p-type at the doping concentration of x = 0.3 due to the excess Ge which increases in hole carrier concentration. Electrical conductivity decreases with an increase in Ge doping concentrations and with increases in temperature due to the bipolar effect. Thermal conductivity increases with an increase in carrier concentration and decreases when the temperature is increased. The highest ZT = 0.58 was achieved by In0.16Co4 Sb11.95Ge0.05 at 673K and In-filled and Ge-doped Co4Sb12 was not effective in improving the figure of merit. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3677982]

Item Type: Journal Article
Publication: Journal of Applied Physics
Publisher: American Institute of Physics
Additional Information: Copyright of this article belongs to American Institute of Physics.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 13 Mar 2012 04:56
Last Modified: 13 Mar 2012 04:56
URI: http://eprints.iisc.ac.in/id/eprint/43714

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