Microstructure regulation and failure mechanism study of BaTiO3-based dielectrics for MLCC application

Most widely used dielectrics for MLCC are based on BaTiO 3 composition which inevitably shows performance degradation during the application due to the migration of oxygen vacancies ( V o ⋅ ⋅ ). Here, the BaTiO 3 , ( Ba 0 . 9 7 Ca 0 . 0 3 )TiO 3 , Ba( Ti 0 . 9 8 Mg 0 . 0 2 )O 3 , ( Ba 0 . 9 7 Ca 0 . 0 3 )( Ti 0 . 9 8 Mg 0 . 0 2 )O 3 , ( Ba 0 . 9 6 Ca 0 . 0 3 Dy 0 . 0 1 )( Ti 0 . 9 8 Mg 0 . 0 2 )O 3 ceramics (denoted as BT, BCT, BTM, BCTM and BCDTM, respectively) were prepared by a solid-state reaction method. The core-shell structured grains ( ∼ 200 nm) featured with 10-20 nm wide shell were observed and contributed to the relatively flat dielectric constant-temperature spectra of BTM, BCTM and BCDTM ceramics. The TSDC study found that the single/ mix doping of Ca 2 + , especially the Mg 2 + , Mg 2 + /Ca 2 + and Mg 2 + /Ca 2 + /Dy 3 + could limit the emergence of V o ⋅ ⋅ during the sintering and suppress its long-range migration under the electric-field. Because of this, the highly accelerated lifetimes of the ceramics were increased and the value of BCDTM is 377 times higher than that of BT ceramics. The p − n junction model was built to explain the correlation mechanism between the long-range migration of V o ⋅ ⋅ and the significantly increased leakage current of BT-based dielectrics in the late stage of HALT.