Mechanism of oxygen vacancies migration in BaTiO <sub>3</sub> ‐Bi <i>Me</i> O <sub>3</sub> : Experimental investigations and first principles studies
Wanqi Liu, Qian Wang, Hong‐Ting Lu, Xian Zhao, Chun‐Ming Wang
Abstract
Abstract BaTiO 3 ‐based compounds are recognized as the most common dielectric material used in multilayer ceramic capacitors (MLCCs), among which, BaTiO 3 ‐Bi Me O 3 is extensively investigated to improve the thermal stability and extend the service life of MLCCs, which are strongly dependent on the conductivity at high temperatures. Despite numerous efforts have been made, the mechanism of oxygen vacancy conduction, which makes the major contributions to the conduction mechanism of BaTiO 3 ‐based compounds at high temperatures below 450°C, is still unclear. In this paper, BaTiO 3 , 0.88BaTiO 3 ‐0.12Bi(Zn 2/3 Nb 1/3 )O 3 , 0.88BaTiO 3 ‐0.12Bi(Mg 2/3 Nb 1/3 )O 3 , and 0.88BaTiO 3 ‐0.12Bi(Mg 2/3 Ta 1/3 )O 3 ceramics have been prepared by solid‐state reaction method, and their electrical and dielectric properties have been studied in detail. Meanwhile, first principles were applied to study the mechanisms of the increase of electrical resistivity and the decrease of dielectric loss. It is found that B ‐site dopants (Zn, Mg, Nb, and Ta) are effective in reducing the conductivity by inhibiting the migration of oxygen vacancies, which is a kinetics process with an increase of energy barrier. Notably, the greater ability of Zn to inhibit oxygen vacancies migration is a combination of thermodynamics (a strong ability to trap oxygen vacancies) and kinetics (an effect of block the migrating defects in the lattice). This work reveals a new insight into the mechanism of oxygen vacancies migration in BaTiO 3 ‐based perovskite compounds, which makes BaTiO 3 ‐Bi Me O 3 prospective in designing efficient and durable medium‐temperature solid oxide capacitor devices.