Microstructure regulation and failure mechanism study of BaTiO<sub>3</sub>-based dielectrics for MLCC application
Yan Gu, Faqiang Zhang, Wanghua Wu, Zhifu Liu
Abstract
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 ([Formula: see text]). Here, the BaTiO 3 , ([Formula: see text][Formula: see text])TiO 3 , Ba([Formula: see text][Formula: see text])O 3 , ([Formula: see text][Formula: see text])([Formula: see text][Formula: see text])O 3 , ([Formula: see text][Formula: see text][Formula: see text])([Formula: see text][Formula: see text])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 ([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.