1999/08/03 by T. Itoh, T. Kawata, T. Kitajima +1
Physics and Astronomy · #cond-mat.str-el
published as Proc. of 17th International Conference on Thermoelectrics (1998) p.595 · LaTex 2.06 eith epsf style, 3 pages, 6 eps figures
arxiv created 1999/08/03 · arxiv updated 2009/11/30
The resistivity and thermopower of polycrystalline (Na,Ca)Co2O4 were measured and analyzed. Both the quantities increase with x, suggesting that the carrier density is decreased by the substitutions of Ca2+ for Na+. Considering that the temperature dependence of the resistivity show a characteristic change with x, the conduction mechanism is unlikely to come from a simple electron-phonon scattering. As a reference for NaCo2O4, single crystals of a two-dimensional Co oxide (Bi,Pb)2M3Co2O9 (M=Sr and Ba) were studied. The Pb substitution decreases the resistivity, leaving the thermopower nearly intact.