Cofiring diffusion behavior of composite multilayer ceramic capacitors with X7R characteristics

The low-sintering composite multilayer ceramic capacitors (CMLCCs) having K-value in excess of 7200 with X7R characteristics (-55+125degreesC, +/-15%) has been successfully developed. The CMLCCs incorporate four PMN-PNN-PT or PMN-PT based ceramics with different Curie temperatures as the principal components. The mutual diffusion among different dielectrics via the inner 30Pd-70Ag electrode is observed in the CMLCCs. Further experiments indicate that some cations such as Ni2+ and Ti4+, which play main roles in the diffusion, present different diffusion behaviors. The most interesting thing is that excessive Ni2+ and Mg2+ congregate in the form of oxides close to the inner electrode where is the dividing line between two kinds of dielectrics. The phenomenon can be explained by the ABO, structure of perovskite.