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Thermoelectric Properties and Magnetic Anisotropies of Magnetically Grain-Oriented Sr- or Bi-doped Ca3Co4O9 Thick Films

Published online by Cambridge University Press:  01 February 2011

Shigeru Horii
Affiliation:
[email protected], The University of Tokyo, Dept. Appl. Chem., Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan
Yuhya Yamasaki
Affiliation:
[email protected], The University of Tokyo, Department of Applied Chemistry, Tokyo, 113-8656, Japan
Masayuki Sakurai
Affiliation:
[email protected], The University of Tokyo, Department of Applied Chemistry, Tokyo, 113-8656, Japan
Ryoji Funahashi
Affiliation:
[email protected], National Institute of Advanced Industrial Science and Technology, Ikeda, 563-8577, Japan
Tetsuo Uchikoshi
Affiliation:
[email protected], National Institute for Materials Science, Tsukuba, 305-0047, Japan
Tohru S Suzuki
Affiliation:
[email protected], National Institute for Materials Science, Tsukuba, 305-0047, Japan
Yoshio Sakka
Affiliation:
[email protected], National Institute for Materials Science, Tsukuba, 305-0047, Japan
Hiraku Ogino
Affiliation:
[email protected], The University of Tokyo, Department of Applied Chemistry, Tokyo, 113-8656, Japan
Jun-ichi Shimoyama
Affiliation:
[email protected], The University of Tokyo, Department of Applied Chemistry, Tokyo, 113-8656, Japan
Kohji Kishio
Affiliation:
[email protected], The University of Tokyo, Department of Applied Chemistry, Tokyo, 113-8656, Japan
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Abstract

We report magnetic properties of [Ca2CoO3-δ]0.62CoO2 (Ca349) powders with various average size and the Bi- and Sr-doping effects on thermoelectric properties for the magnetically grain-aligned and densified Ca349 thick films. Magnetic anisotropy at 300 K depended on the initial average size of Ca349 powders and decreased with the decrease in the size. This presumably suggests that distortion of crystal structure was induced by a ball-milling process and led to the change of magnetic anisotropy. On the Bi- and Sr-doping effects, an obvious enhancement of thermoelectric properties did not emerge in the case of the Sr-doping, whereas the enhancement was observed for the Bi-doped Ca349 thick films. However, a drastic decrease of magnetic anisotropy was caused by the Bi-doping. For usage of the p-type layer in multilayered thermoelectric module, tuning of the Bi-doping levels in which both enhancement of thermoelectric properties and a certain level of magnetic anisotropy are achieved is required.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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