From oxides to selenides and sulfides: The richness of the CdI2 type crystallographic structure for thermoelectric properties

S. Hébert*, Wataru Kobayashi, H. Muguerra, Y. Bréard, N. Raghavendra, F. Gascoin, E. Guilmeau, A. Maignan

*この研究の対応する著者

研究成果: Article査読

64 被引用数 (Scopus)

抄録

In this paper, we show how the thermoelectric properties can be modified in crystallographic structures based on the CdI2 type layer, by changing the block layers between these CdI2 type layers or by going from oxides to selenides and sulfides. In the case of oxides, the unique properties generated in these structures will be demonstrated in Bi-based misfit compounds. By combining Hall effect, resistivity, and Seebeck coefficients in single crystals of this family, the importance of doping and of spin and orbital degeneracy term on the Seebeck coefficient will be shown. From this single crystal investigation, the power factor at 300 K is found to be unexpectedly constant as a function of doping. To further enhance the power factor and thus ZT, it is necessary to modify either the block layer or to perform anionic substitutions. By going from oxides to selenides and sulfides, the decrease of the ionic character can induce a decrease of electrical resistivity. Compared to oxides, the properties can generally be described in a more classical way using Boltzmann transport theory. For these materials, the critical parameter is then thermal conductivity and this quantity can be decreased as shown here by intercalating Cu between the layers (CuxTiS2), or by making solid solution such as TiS2 - xSex. These two approaches will be described here, leading to ZT close to 0.5 and 0.4, at 800 and 700 K, respectively. The CdI2 type crystallographic structure is a very rich family in which oxides and non-oxide materials can be synthesized. For oxides, NaxCoO2 has already been found to be a promising p-type thermoelectric material. The aim of this Feature Article is first to analyze the thermoelectric properties of misfit cobalt oxides, showing the relationship between this layered structure which stabilizes Co3+ and Co4+ in low spin states, and transport properties. By changing the separating block layer, or by modifying oxides into selenides or sulfides, it is possible to strongly modify the transport properties. The second part of this Feature Article reports the interesting thermoelectric properties of sulfides and selenides, with ZT up to 0.5 at 800 K, and shows the differences between these properties and that of oxides.

本文言語English
ページ(範囲)69-81
ページ数13
ジャーナルPhysica Status Solidi (A) Applications and Materials Science
210
1
DOI
出版ステータスPublished - 2013 1
外部発表はい

ASJC Scopus subject areas

  • 電子工学および電気工学
  • 電子材料、光学材料、および磁性材料
  • 材料化学
  • 凝縮系物理学
  • 表面および界面
  • 表面、皮膜および薄膜

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