Electrical conductivity of iron-doped calcium titanate

Abstract

Both total and partial electronic conductivity of iron-doped calcium titanates, of general formula CaTi 1− x Fe x O 3−δ ( x=0, 0.1,…0.5), were investigated as a function of oxygen partial pressure at high temperatures (900, 1000°C) by means of the four-probe technique and the Hebb–Wagner polarization method, respectively. The oxygen partial pressure interval extended from 1 to 10 −18 atm. Ti substitution by Fe results in a considerable increase of both ionic and electronic conductivity and in appearance of a wide region of primarily ionic conductivity, independent of the oxygen partial pressure. Of these compositions, the x=0.2 sample has the highest oxygen ion conductivity. A model of defect equilibrium is discussed.