Observations of Co4 + in a higher spin state and the increase in the seebeck coefficient of thermoelectric Ca 3Co 4O 9

R.F. Klie, Q. Qiao, T. Paulauskas, A. Gulec, Alejandro F. Rebola, Serdar Ogut, M.P. Prange, Juan Carlos Idrobo , Sokrates T Pantelides, Stanislaw Kolesnik, Bogdan Dabrowski, Mustafa Ozdemir, Cihat Boyraz, Dipanjan Mazumdar, Arunava Gupta

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Ca 3Co 4O 9 has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca 3Co 4O 9 thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4 +-ions in a higher spin state compared to that of bulk Ca 3Co 4O 9. The higher Seebeck coefficient makes the Ca 3Co 4O 9 system suitable for many high temperature waste-heat-recovery applications.

Original languageEnglish
Article number196601
Pages (from-to)1-5
Number of pages5
JournalPhysical Review Letters
Issue number19
Publication statusPublished - 8 May 2012
Externally publishedYes

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