High temperature electrical behavior of CaTi1 − xFexO3 − δ (x = 0–0.5). Oxygen-ion, electronic and proton conductivity

Total electrical conductivity and contributions of different charge carriers such as oxygen ions, protons, electrons and holes in CaTi1 − xFexO3 − δ (x = 0–0.5) were measured as functions of temperature, oxygen partial pressure and iron content. Total electrical conductivity measurements were made by means of the four-probe dc technique. Partial electronic conductivity was studied by the Hebb–Wagner polarization method. Transport numbers of oxygen ions and protons in CaTi1 − xFexO3 − δ were measured by the EMF method. It has been shown that CaTi1 − xFexO3 − δ is a mixed oxygen-ion and electronic conductor at small iron concentrations, and it is a predominantly electronic conductor at large iron contents. Proton conductivity of CaTi1 − xFexO3 − δ is negligibly small. Ambipolar conductivity of CaTi1 − xFexO3 − δ was calculated. With known ambipolar conductivity a profile of the oxygen chemical potential inside CaTi1 − xFexO3 − δ under applied oxygen partial pressure gradient can be figured out.