The typical characterizations with the SIMS technique of zinc oxide and transparent YAG ceramics were discussed. In zinc oxides, Bi ions segregate along the grain boundaries and give acceptor levels, and they behave as a varistor. The cation and oxygen diffusion coefficients were measured in the transparent YAG ceramics. It has been shown that the creep properties were controlled by the cation diffusion at the yttrium sites. (C) 2002 Elsevier Science B.V. All rights reserved.