Finite element modeling on the effect of intra-granular porosity on the dielectric properties of BaTiO3 MLCCs

Abstract

The effect of porosity on the electrical properties of BaTiO3-based Multilayer Ceramic Capacitors (MLCCs) is studied. A dense ceramic prepared via powder from a solid-state processing route is compared against a ceramic that contains intra-granular pores from powder prepared via hydrothermal processing. Finite element models are created to contain intra-granular pores, solved and analyzed to show an increase in the electric field and current density surrounding the pores. For single-pore and two intra-pore arrangements, the electric field is enhanced by a factor of ~1.5 and 2.5, respectively, when compared to a fully dense (pore-free) material. For ceramics with equivalent density, the number of pores dramatically alters the electrical response. For a system containing 100 pores, the electric field can increase at least fourfold, therefore facilitating a possible starting route for electrical breakdown of the grain. These results are compared to the Gerson-Marshall model, typically used in the literature for the calculation of the breakdown strength due to porosity. The results highlight the need to include the effect of adjacent pore interactions. Although studied here for BaTiO3-based MLCC's the results are applicable to other devices based on ceramics containing porosity.