Ca 1-x RE x MnO 3 (RE: Nd, Tb, Ho, Yb, Lu, x = 0.1 and 0.2) bulks were prepared by a solid state reaction. They show metallic behavior at temperatures higher than about 400 K and electrical resistivity ρ is lower than 12 mΩ cm at 1000 K in air. Absolute values of Seebeck coefficient S increases with temperature up to 973 K for all samples except Ca 0.9 Yb 0.1 MnO 3 at 973 K. For Ca 0.9 Lu 0.1 MnO 3 , S value reaches -130 μV/K at 973 K. Both thermoelectric properties are dominated mainly by crystallographic structure. Power factor PF (=S 2 /ρ) increases with decreasing cell volume.Thermal conductivity κ of Yb-and Lu-substituted samples is as low as 1.5 W/m-K 2 and dimension-less figure of merit ZT reaches 0.16 at 973 K for Ca 0.8 Lu 0.2 MnO 3 in air.

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