Title :
Transport properties in (Na,Ca)Co2O4 ceramics
Author :
Itoh, T. ; Kawata, T. ; Kitajima, T. ; Terasaki, I.
Author_Institution :
Dept. of Appl. Phys., Waseda Univ., Tokyo, Japan
Abstract :
The resistivity and thermopower of polycrystalline Na1.1-x CaxCo2O4 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 Bi2-xPbxM3Co 2O9 (M=Sr and Ba) were studied. The Pb substitution decreases the resistivity, leaving the thermopower nearly intact
Keywords :
calcium compounds; carrier density; ceramics; electrical resistivity; sodium compounds; thermoelectric power; NaCaCo2O4; carrier density; ceramics; electron-phonon scattering; polycrystalline sample; resistivity; substitution; temperature dependence; thermopower; Bismuth; Ceramics; Charge carrier density; Conductivity; Copper; Crystals; Grain boundaries; Solid state circuits; Strontium; Temperature dependence;
Conference_Titel :
Thermoelectrics, 1998. Proceedings ICT 98. XVII International Conference on
Conference_Location :
Nagoya
Print_ISBN :
0-7803-4907-5
DOI :
10.1109/ICT.1998.740449
