The bulk and grain-boundary diffusion of 18O at 1673K, and Mg and Ca distributions in polycrystalline MgO-doped material, were studied by using a secondary ion mass spectrometry technique. The second phase contained Mg and Ca near to the surface. It was found that the formation and growth rate of the second phase depended upon the grain boundary orientation. The O profile along grain boundaries was affected by the distribution of the second phase; especially near to the surface.

I.Sakaguchi, H.Haneda, V.Srikanth, T.Ikegami: Materials Research Bulletin, 1996, 31[7], 837-43