Observations of Co4+ in a higher spin state and the increase in the Seebeck coefficient of thermoelectric Ca3Co4O9
journal contribution
posted on 2013-11-07, 00:00 authored by R. F. Klie, Q. Qiao, T. Paulauskas, A. Gulec, A. Rebola, M. P. Prange, J. C. Idrobo, S. T. Pantelides, S. Kolesnik, B. Dabrowski, M. Ozdemir, C. Boyraz, D. Mazumdar, A. Gupta, S. ÖğütCa3Co4O9 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 Ca3Co4O9 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 Ca3Co4O9. The higher Seebeck coefficient makes the Ca3Co4O9 system suitable for many high temperature waste-heat-recovery applications.
Funding
This work was supported by the NSF [DMR-0846748 (R. F. K.), DMR-0938330 (J. C. I.)], by ORNL’s Shared Research Equipment (SHaRE) User Program, sponsored by the DOE Office of Basic Energy Sciences (J. C. I.), DOE [DE-FG02-09ER46554 (M. P. P., S. T. P.)], by DOE [DE-AC02-06CH11357 (S. K., B. D.)], by the McMinn Endowment (S. T. P.) at Vanderbilt University, and the U.S. Army Research Office (W911NF-10-1-0147). S. Ö. acknowledges support by the National Science Foundation under the Independent Research/Development program while working at the Foundation.
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Publisher Statement
This is a copy of an article published in the Physical Review Letters © 2012 American Physical Society.Publisher
American Physical SocietyLanguage
- en_US
issn
1079-7114Issue date
2012-05-01Usage metrics
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