Influence of rare earth diffusion in BaTiO3-based MLCCs sintered in a reducing atmosphere

초록

Here, the purpose is to investigate rare earth-rich MLCCs fabricated by sintering in a reducing atmosphere with variable oxygen partial pressure (pO2) ranging from 5.9 & times; 10-9 to 1.3 & times; 10-9 atm to meet the market demand for automotive MLCC with long-term lifetime reliability. An increase in the average grain size was observed as pO2 decreased, which is attributed to enhanced atomic diffusion under reducing conditions. It is clearly observed that Dy segregates at the grain boundaries to form a Dy-rich shell region due to its low lattice solubility, resulting in the enhanced mean-time-to-failure from 168 to 246 h under highly accelerated lifetime evaluation. In addition, as pO2 decreases, the temperature at the maximum dielectric permittivity shifts to a higher temperature from 34.5 to 43.3 degrees C toward Curie temperature for pure BT (125 degrees C) because of low Dy concentration in the shell region.

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