Temperature activated electron transport in CaMnO3

The electrical conductivity, thermopower, DTA and TG measurements were carried out at heating of CaMnO3−δ in air within the temperature range 300–1300 K. The concentration of electrons in CaMnO3−δ at δ → 0 was derived from the defect model based on simultaneous reactions of oxygen exchange and thermal excitation of electrons. The calculation results and experimental data for electrical conductivity were combined in order to obtain drift mobility of the charge carriers at 700–900 K. The mobility activation energy is found to be about 0.07 eV. It is shown that electron transport properties in CaMnO3 at elevated temperatures can be explained in terms of activated jumps of n-type adiabatic small polarons. The relatively small mobility is explained by strong localization of the polarons on manganese sites.