Relation between Seebeck Coefficient and Lattice Parameters of (Ca2-ySryCoO3)xCoO2

Title
Relation between Seebeck Coefficient and Lattice Parameters of (Ca2-ySryCoO3)xCoO2
Authors
권오정조욱윤세진신동민유현우최경달김진상박찬
Keywords
Thermoelectricity; oxide thermoelectric materials; layered structure; Ca3Co4O9; Rietveld refinement
Issue Date
2012-06
Publisher
Journal of electronic materials
Citation
VOL 41, NO 6, 1513-1518
Abstract
The effect of dopant content on the Seebeck coefficient of the Sr2+-doped (Ca2−y Sr y CoO3) x CoO2 (y = 0 to 0.4) system was investigated. This system can be described as a misfit layered structure of (CoO2) and (Ca2−y Sr y CoO3) layers, which have different b lattice parameters denoted by b 1 and b 2, respectively. Due to the solubility limit of Sr in (Ca2CoO3) x CoO2, systematic investigations were available only up to y = 0.2. Nevertheless, the structural uniqueness enabled partially quantitative analysis of the correlation between the crystal structure and Seebeck coefficient of the system. Substitution of Sr for Ca leads to lattice expansion which accompanies an anisotropic change of the lattice parameters. Among the lattice parameters considered, the increase in the lattice parameter b 2 of the insulating layer was larger than the change of any other lattice parameter, which induced in-plane stress in the conducting layer. As a result, as the b 1/b 2 misfit ratio of (Ca2−y Sr y CoO3) x CoO2 is decreased, the Seebeck coefficient also decreases. Practical guidance for selecting dopants to enhance thermoelectric performance is proposed.
URI
http://pubs.kist.re.kr/handle/201004/42626
ISSN
03615235
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KIST Publication > Article
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