A structural change in Ca 3Co 4O 9 associated with enhanced thermoelectric properties

Document Type

Article

Publication Date

11-14-2012

Abstract

Temperature dependent electrical resistivity, crystal structure and heat capacity measurements reveal a resistivity drop and electrical transport behavior change corresponding to a structural change near 400K in Ca 3Co 4O 9. The lattice parameter c varies smoothly with increasing temperature while anomalies in a, b 1 and b 2 lattice parameters occur near 400K. The Ca site in the Ca 2CoO 3 block becomes distorted and a change in electrical transport behavior is found above 400K. Resistivity and heat capacity measurements as a function of temperature under magnetic field combined with CoL-edge x-ray absorption spectra reveal only a weak spin contribution to this change. Reduced resistivity associated with the structural change enhances the thermoelectric properties at moderately high temperatures and points to the electrical transport behavior change as a mechanism for improved ZT in this thermoelectric oxide. © 2012 IOP Publishing Ltd.

Identifier

84867952394 (Scopus)

Publication Title

Journal of Physics Condensed Matter

External Full Text Location

https://doi.org/10.1088/0953-8984/24/45/455602

e-ISSN

1361648X

ISSN

09538984

Issue

45

Volume

24

Grant

0923032

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