THERMAL-STABILITY OF CE1-XZRXO2 SOLID-SOLUTION POWDERS

High surface area Ce1-xZrxO2 powders (0 < x < 0.36) were annealed at 9 50 degrees C. The surface area variation versus time of calcination wa s followed I BET method for ail the samples. When the experimental rat es of the surface area decrease are plotted ver sus x, title extremes are observed. a minimum around 0.09 and a maximum around 0.19. Our pre vious model involving oxygen and cerium diffusion proposed to interpre t the stabilizing effect of zirconium at low content in ctl ia cannot account for the present experimental rate variations. We propose that the assumption of the ideal behaviour of the solutions is Ito longer v alid when x reaches values as high as 0.32 and 0.36. Thus, provided th at the Ce1-xZrxO2 phases ale considered as strictly regular solutions and on the basis of the kinetic model for cei in, it can be Shown that the present experimental rate can be interpreted. (C) 1998 Elsevier S cience Limited. All rights reserved.