Chin.Phys.Lett.  2017, Vol. 34 Issue (03): 037101    DOI: 10.1088/0256-307X/34/3/037101
 CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
Electronic Structure and Thermoelectric Power Factor of Na$_{x}$CoO$_{2}$ from First-Principles Calculation
Peng-Xian Lu1**, Rui-Xia Zhao2
1College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001
2Department of Civil Engineering and Architecture, Henan Technical College of Construction, Zhengzhou 450001
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Abstract To investigate the relationship between the electronic structure and the power factor of Na$_{x}$CoO$_{2}$ ($x=0.3$, 0.5 and 1.0), the first-principles calculation is conducted by using density functional theory and the semi-classical Boltzmann theory. Our results suggest that with the decreasing Na content, a transition from semiconductor to semimetal is observed. Na$_{0.3}$CoO$_{2}$ possesses a higher electrical conductivity at 1000 K due to its increased density of states near the Fermi energy level. However, an optimal Seebeck coefficient at 1000 K is obtained in Na$_{0.5}$CoO$_{2}$ because of its broadened band gap near the Fermi energy level. Consequently, a maximum power factor is realized in Na$_{0.5}$CoO$_{2}$. Thus our work provides a complete understanding of the relationship between the electronic structure and the thermoelectric power factor of Na$_{x}$CoO$_{2}$.
Received: 04 November 2016      Published: 14 March 2017
 PACS: 71.20.Nr (Semiconductor compounds) 72.20.Pa (Thermoelectric and thermomagnetic effects)
Fund: Supported by the Science Foundation of Henan University of Technology under Grant No 2015XTCX10.
Issue Date: 14 March 2017
 Cite this article: Peng-Xian Lu,Rui-Xia Zhao 2017 Chin.Phys.Lett. 34 037101 URL: http://cpl.iphy.ac.cn/newweb/10.1088/0256-307X/34/3/037101       OR      http://cpl.iphy.ac.cn/newweb/Y2017/V34/I03/037101