Structure and properties of the one-dimensional cobalt oxide CaCo2O4 |
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Authors: | M Isobe M Arai T Kawashima E Takayama-Muromachi |
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Institution: | aSuperconducting Materials Center, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan;bComputational Materials Science Center, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan |
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Abstract: | We have studied crystal structure and transport properties of the quasi one-dimensional cobalt oxide CaCo2O4. The CaCo2O4 phase crystallizes in calcium-ferrite type structure, which consists of a corner- and edge-shared CoO6 octahedron network including one-dimensional double chains. Large thermoelectric power (S 150 μV/K at 390 K) with metallic temperature dependence of S, moderate resistivity (ρ 2.9 × 10−1 Ω cm at 390 K) with carrier localization at low temperature, and normal thermal conductivity (κ 6.3 W/Km at 390 K) were observed. The phonon mean-free path was calculated from the observed data, as a function of temperature. The long phonon mean-free path (l 24 Å at 300 K) implies that the thermal conductivity could be suppressed by impurity scattering of phonons with partial element substitution. |
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Keywords: | Calcium cobalt oxide Calcium-ferrite type structure Quasi one-dimensional system Thermoelectric material |
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