SURFACE-AREA STABILITY OF LANTHANUM-DOPED CERIA

High surface area ceria was doped with lanthanum ions and calcined at 900 K under various partial pressures of oxygen and water vapour. The kinetic rates of crystallite size increase were observed to vary as P( O2)-1/6. By addition of 0.5 and 1% of lanthanum ions, the rates were l owered, and then significantly decreased for 10% (cat.). A model of th is process involved association between lanthanum ions and oxygen vaca ncies in order to explain the better stability of doped ceria.