Enhanced asymmetrical transport of carriers induced by local structural distortion in chemically tuned titania: A possible mechanism for enhancing thermoelectric properties

C. Liu, L. Miao, D. Hu, R. Huang, C. A.J. Fisher, S. Tanemura, H. Gu

研究成果: Article査読

8 被引用数 (Scopus)

抄録

Optimizing all three thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal conductivity) simultaneously is a nontrivial task, especially for the Seebeck coefficient and electrical conductivity. Here, we demonstrate that chemically tuned rutile TiO2 sintered from N- and Nb-codoped nanoparticles possesses not only an enhanced power factor but also a decreased thermal conductivity. In samples produced under strongly reducing conditions, the electrical resistivity is decreased markedly to 3.96×10-5 Ωm while maintaining a high Seebeck coefficient. In this manner, the power factor can be greatly improved to 9.87×10-4 W m-11 K-2 at 785 C with a significantly enhanced figure of merit ZT of 0.35 at 700 C. Theoretical modeling based on density functional theory suggests that enhanced asymmetrical carrier transport (i.e., with the minority carrier relatively localized on one side of the Fermi level but the majority carrier delocalized on the other) can be induced by locally distorting the crystal structure, since this imposes local perturbations on the intrinsic periodic potential field, which may be responsible for the improved power factor. The greatly improved thermoelectric behavior of chemically tuned rutile TiO2 provides a promising route to producing practical thermoelectric materials without the use of toxic heavy elements. Our findings also provide a promising new strategy for enhancing the thermoelectric properties of other thermoelectric materials.

本文言語English
論文番号205201
ジャーナルPhysical Review B - Condensed Matter and Materials Physics
88
20
DOI
出版ステータスPublished - 2013 11 7
外部発表はい

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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