The interface between dielectric layers (BaTiO3) and internal electrode layers (Ni) in X7R type multilayer ceramic capacitors with an active layer thickness of 5µm was studied by scanning electron microscopy, high-resolution transmission electron microscopy, selected-area electron diffraction and energy-dispersive spectroscopy. Weak interdiffusion was observed between dielectric layers and internal electrode layers. It was found that it was easier for Ni to diffuse into the BaTiO3 perovskite lattice than for BaTiO3 to diffuse into the Ni lattice while neither of the two diffusions extended for a long distance, which was approximately 8nm on the BaTiO3 side and 3nm on the Ni side.

Observation on the Interdiffusion in Multilayer Ceramic Capacitors. H.Wen, X.Wang, L.Li: Japanese Journal of Applied Physics, 2006, 45[3A], 1768-70