Thermoelectric properties of Ba 3 Co 2 O 6 ( CO 3 ) 0.7 containing one-dimensional CoO 6 octahedral columns

• Published in: Journal of applied physics 2009-08, Vol.106 (3), p.034905-034905-5
• Main Authors: Iwasaki, Kouta, Yamamoto, Teruhisa, Yamane, Hisanori, Takeda, Takashi, Arai, Shigeo, Miyazaki, Hidetoshi, Tatsumi, Kazuyoshi, Yoshino, Masahito, Ito, Tsuyoshi, Arita, Yuji, Muto, Shunsuke, Nagasaki, Takanori, Matsui, Tsuneo
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3174428

The thermoelectric properties of Ba 3 Co 2 O 6 ( CO 3 ) 0.7 have been investigated using prismatic single crystals elongated along the c axis. Ba 3 Co 2 O 6 ( CO 3 ) 0.7 has a pseudo-one-dimensional structure similar to that of 2H perovskite-type BaCoO 3 and contains CoO 6 octahedral columns running parallel to the c axis. The prismatic crystals are grown by a flux method using a K 2 CO 3 - BaCl 2 flux. The electrical conductivity ( σ ) along the columns ( c axis) exhibits a metallic behavior ( 670 - 320   S cm − 1 in the temperature range of 300-1100 K), whereas the temperature dependence of the electrical conductivity perpendicular to the c axis is semiconducting. The Seebeck coefficient ( S ) along the columns is positive and greater than 100   μ V K − 1 over the measured temperature range ( 116 - 128   μ V K − 1 ) . Ba 3 Co 2 O 6 ( CO 3 ) 0.7 shows power factors ( σ S 2 ) of 5.5 × 10 − 4 - 9.0 × 10 − 4   W m − 1 K − 2 above room temperature, relatively high values for an oxide material.