Mechanical activation of CeO2-ZrO2-SiO2 mixtures was performed in a high en
ergetic vibratory mill with WC lining and grinding media. It was shown that
in air atmosphere the reduction of Ce4+ into Ce3+ took place at 1400 degre
es C. The Ce3+ ion is stable in air in the form of Ce-2(WO4)(3) contrary to
the Ce3+ ion in Ce-silicates. (C) 1999 Published by Elsevier Science S.A.
All rights reserved.