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Transport Properties in (Na,Ca)Co_2O_4 Ceramics

T. Itoh·T. Kawata·T. Kitajima·I. Terasaki
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Abstract

The resistivity and thermopower of polycrystalline (Na,Ca)Co_2O_4 were measured and analyzed. Both the quantities increase with x, suggesting that the carrier density is decreased by the substitutions of Ca^{2+} 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 NaCo_2O_4, single crystals of a two-dimensional Co oxide (Bi,Pb)_2M_3Co_2O_9 (M=Sr and Ba) were studied. The Pb substitution decreases the resistivity, leaving the thermopower nearly intact.

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T. Itoh, T. Kawata, T. Kitajima, I. Terasaki. 1999-08-03. Transport Properties in (Na,Ca)Co_2O_4 Ceramics. https://arxiv.org/abs/cond-mat/9908039

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