Effect of the Yb substitutions on the thermoelectric properties of CaMnO3

Ca_1-xYb_xMnO₃ (x = 0-0.5) samples were prepared via solid state reaction in air. Electrical and thermoelectric properties have been investigated up to 1000 K. The measurements reveal that the resistivity values are strongly affected by the charge carrier content and the octahedral distortion. The lowest rho reaches 3 mOmegamiddotcm for x = 0.15. Whereas the Seebeck coefficient depends only on the charge carrier concentration, the thermal conductivity of Ca_1-xYb_xMnO₃ is mainly governed by the mass difference between the Yb and Ca cations. The best ZT value, ZT = 0.2, is obtained for x = 0.05 at 1000 K and demonstrates the good potentialities of these oxides as high temperature thermoelectric material