Thermoelectric power of doped cerium oxide

Thermoelectric power and electrical conductivity of CeO2 doped with 2.5, 5 and 20 mole % CaO and 10 mole % Gd2O3 were determined as function of oxygen partial pressure (Po-2) at 1000 degrees C and as function of temperature at three different Po(2)s. The conductivity measurements show ionic conduction at high Po-2 and n-type conduction in reducing atmospheres. The thermoelectric power is positive in the ionic conducting regime and negative for the n-type conduction. The thermoelectric power depends on temperature, except for very low Po-2, and shows a contribution from electronic conduction already at very small electronic transference numbers.