Electrical conduction nature and phase transition in CaTi1−x FexO3−δ (x = 0.1–0.5)

Abstract

Transport numbers for oxygen ions and protons are measured by an emf method in the system CaTi1−x FexO3−δ (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−δ 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−δ are studied as a function of the partial pressure of oxygen at 1173 K. The nature of electroconduction in CaTi1−x FexO3−δ is discussed.