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

Abstract

Most widely used dielectrics for MLCC are based on BaTiO3 composition which inevitably shows performance degradation during the application due to the migration of oxygen vacancies ([Formula: see text]). Here, the BaTiO3, ([Formula: see text][Formula: see text])TiO3, Ba([Formula: see text][Formula: see text])O3, ([Formula: see text][Formula: see text])([Formula: see text][Formula: see text])O3, ([Formula: see text][Formula: see text][Formula: see text])([Formula: see text][Formula: see text])O3 ceramics (denoted as BT, BCT, BTM, BCTM and BCDTM, respectively) were prepared by a solid-state reaction method. The core-shell structured grains ([Formula: see text]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[Formula: see text], especially the Mg[Formula: see text], Mg[Formula: see text]/Ca[Formula: see text] and Mg[Formula: see text]/Ca[Formula: see text]/Dy[Formula: see text] could limit the emergence of [Formula: see text] 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 [Formula: see text] junction model was built to explain the correlation mechanism between the long-range migration of [Formula: see text] and the significantly increased leakage current of BT-based dielectrics in the late stage of HALT.