A study of microstructure and properties of BaTiO 3 from solid‐state and hydrothermal synthesis on MLCCs performance

Abstract It has generally been believed that the performance of ultra‐thin multilayer ceramic capacitors (MLCCs) are mainly controlled by doping elements and the contribution of synthesis approaches of BaTiO 3 (BT) powders can be neglected. However, in this study, we demonstrate that the solid‐state powders exhibit a heterogeneous distribution of residual BaCO 3 (BC), TiO 2 , or Ti‐rich phases, whereas hydrothermal powders are characterized by a BC surface layer, which can be characterized by nanoinfrared (AFM‐IR), and the divergent approaches play an important role in the “core–shell” structure. The BC layer in hydrothermal BT contributes to Ti vacancies during sintering, increasing the “core–shell” ratio in MLCCs. This results in augmented capacitance but reduced performance at elevated temperatures. Conversely, the presence of a Ti‐rich phase in solid‐state powders induces Ba vacancies, leading to decreased “core–shell” ratios and dielectric constants.