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

Yan Gu; Faqiang Zhang; Wanghua Wu; Zhifu Liu

doi:10.1142/S2010135X23500029

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 (

V_{o}^{\cdot \cdot}

). Here, the BaTiO₃, (

{Ba}_{0.97}

{Ca}_{0.03}

)TiO₃, Ba(

{Ti}_{0.98}

{Mg}_{0.02}

)O₃, (

{Ba}_{0.97}

{Ca}_{0.03}

)(

{Ti}_{0.98}

{Mg}_{0.02}

)O₃, (

{Ba}_{0.96}

{Ca}_{0.03}

{Dy}_{0.01}

)(

{Ti}_{0.98}

{Mg}_{0.02}

)O₃ ceramics (denoted as BT, BCT, BTM, BCTM and BCDTM, respectively) were prepared by a solid-state reaction method. The core-shell structured grains (

\sim

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}^{\cdot \cdot}

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}^{\cdot \cdot}

and the significantly increased leakage current of BT-based dielectrics in the late stage of HALT.