Electrical conduction nature and phase transition in CaTi1-xFexO3-δ (x=0.1-0.5)

Transport numbers for oxygen ions and protons are measured by an emf method in the system CaTi1-xFexO3-delta (x = 0.1 - 0.5) in the oxidizing and reducing atmospheres in the temperature interval 973 - 1173 K. It is shown that the compounds under study are mixed ion-electron conductors at small iron concentrations and electron conductors, at large iron contents. The proton conductivity in the compounds is very poor and does not exceed 0.5% in air. On the basis of the temperature dependences of transport numbers for ions and linear expansion, it is established that the CaTi0.9Fe0.1O3-delta system has a phase transition of a second order in a reducing environment at 1020 - 1050 K. The total and partial electron conductivities of CaTi0.9Fe0.1O3-delta are studied as a function of the partial pressure of oxygen at 1173 K. The nature of electroconduction in CaTi1-xFexO3-delta is discussed.