Transport Properties of Ca1 – xMnO3 – δ + xCeO2(0 < x ≤ 0.15) Mixtures

Data are presented on the temperature-dependent electrical conductivity and thermoelectric power of Ca1 – xMnO3 – δ + xCeO2 (0 < x ≤ 0.15) mixtures obtained as intermediate products in the synthesis of Ca1 – xCexMnO3 – δ solid solutions. The electrical properties of the mixtures are shown to be dominated by those of the perovskite-like phase Ca1 – xMnO3 – δ and to depend on Ca concentration. All of the samples with 0 ≤ x ≤ 0.15 exhibit n-type conductivity. The charge transport in CaMnO3 – δ below 930 K is attributable to small-polaron hopping. At higher temperatures, conduction through delocalized states seems to prevail. In the Ca1 – xMnO3 – δ + xCeO2 mixtures with 0.05 ≤ x ≤ 0.15, small-polaron hopping is observed between 160 and 920 K. Below 160 K, the temperature variation of conductivity in the samples with x = 0.1 and 0.15 follows Mott's law.