Transport properties and defect structure of nonstoichiometric yttria doped ceria

The electrical properties of ceria doped with yttria (10 mol.%) were investigated between 1273 and 1673 K for a large range of oxygen partial pressure. The study of the total electrical conductivity, carried out using a four probe d.c. method, has made it possible to demonstrate the mixed nature, ionic and electronic, of the transport properties. The concentrations of the various charge carriers responsible for the mixed conductivity have been determined using thermogravimetry and magnetic susceptibility equipment at high temperature. From the thermogravimetric measurements, the deviation from the stoichiometric composition of the material in the reference state (T,Psub(O2) = 10-1 MPa) has been derived and the variation of the departure from stoichiometry versus temperature and oxygen partial pressure has allowed the characterization of the defect structure of the material. On the basis of these results, a first modeling of the oxygen partial pressure dependence of the electrical properties has been achieved. (author)