Observation of Distinct Metallic Conductivity in NaCo2O4

Abstract

Electrical conductivity and powder X-ray studies have been made on (Sr_1-αNa_[α])CoO _x after firing at 980°C in air. The data are explainable in terms of the mixed phase of SrCoO _x (x∼2.5) and NaCo₂O₄. We found a distinct metallic conductivity in NaCo₂O₄; the resistivity decreases linearly to 12 K from room temperature. This compound may be another candidate mother oxide for future study of high-temperature superconductivity.