Enhanced DC-bias stability and reliability in BaTiO₃ ceramics via B-site Ca doping induced long-range order disruption

With the ongoing miniaturization of multilayer ceramic capacitors (MLCCs), there is an increasing demand for dielectric materials that simultaneously exhibit high dielectric constant, excellent DC-bias stability, and high reliability. To address this challenge, B-site Ca doping was employed to regulate the polar structure of BaTiO₃-based ceramics. In this study, we systematically investigated the effects of Ca doping on the crystal structure, defects, and microstructure by varying the dopant concentration and occupancy behavior. The B-site Ca-doped BaTiO₃ ceramics exhibit a pseudo-cubic structure, characterized by the coexistence of tetragonal and cubic phases. Ca²⁺ substitution for Ti⁴⁺ disrupts the long-range ferroelectric order, leading to the formation of polar nanoregions (PNRs) interconnected and embedded within a non-polar matrix. Defect analysis and studies on reducing atmosphere sintering reveal that oxygen vacancies are effectively localized by cation defects, thereby suppressing long-range conduction. These structural features synergistically result in high dielectric constant, superior DC-bias stability, enhanced insulation resistance, and strong non-reducibility. This work provides fundamental insights into the microstructural design of BaTiO₃-based ceramics and highlights their potential for high-reliability MLCC applications.