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 con