Observations of Co4+ in a Higher Spin State and the Increase in the Seebeck Coefficient of Thermoelectric Ca3Co4O9
Observations of Co4+ in a Higher Spin State and the Increase in the Seebeck Coefficient of Thermoelectric Ca3Co4O9
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DOI：
10.1103/physrevlett.108.196601
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发表时间：
2012-05-08
影响因子：
8.6
通讯作者：
Gupta, A.
中科院分区：
文献类型：
--
作者：
Klie, R. F.;Qiao, Q.;Gupta, A.
Ca3Co4O9具有独特的结构，导致了异常高的热电传输。本文报道了Ca3Co4O9薄膜的室温面内Seebeck系数提高了27%。我们结合像差校正的Z衬度成像、原子-柱分辨电子能量损失谱和密度泛函计算表明，这种增加是由于Co4+离子处于比体相Ca3Co4O9更高的自旋态的堆积缺陷造成的。较高的Seebeck系数使Ca3Co4O9系统适合于许多高温余热回收应用。
Ca3Co4O9 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.