PROPERTIES OF CEO2 AND CEO2-X FILMS .2. HIGH-TEMPERATURE PROPERTIES

High temperature X-ray investigations of CeO2 films gve a linear thermal expansion coefficient of 11.6 x 10(-6) K-1, corresponding to a temperature dependence of the lattice parameter of a0 = (5.4067 + T x 6.37 x 10(-5)) angstrom. At oxygen partial pressures p(O2) of 0.2-10(-22) bar and at temperatures between 800 and 1100-degrees-C, the lattice parameter of alpha'-CeO2 changes linearly with the oxygen partial pressure. The conductivity of substoichiometric CeO2 in the field of the alpha' phase also changes linearly with the oxygen partial pressure. A plot of p(O2) vs. the conductivity sigma gives a straight line with a slope sigma almost-equal-to p(O2)-1/6. This slope is constant over the total range of temperatures and oxygen partial pressures. So CeO2 thin films can be used for high temperature oxygen sensors.