Enhance temperature stability and reliability for Ho/Mg co-doped ultra-thin BaTiO3-based MLCCs via core-shell structure and oxygen vacancy engineering

Multilayer ceramic capacitors (MLCCs) are used in harsh environments such as automotive electronics, which require high reliability and temperature stability. Therefore, the regulation of Ho/Mg co-doping on the core-shell structure of BaTiO 3 -based MLCCs and the effect on temperature stability and reliability were investigated in this study. Ceramics and MLCCs device with various Ho/Mg molar ratios (1.2–1.8) were prepared using the solid-state reaction method. The study revealed the synergistic effects of Ho/Mg doping on shell concentration, shell thickness, and oxygen vacancy inhibition. The results showed that with the Ho/Mg molar ratio increase, the shell thickness increased from 27.98% to 62.24%. The temperature coefficient of capacitance (TCC) for the sample with Ho/Mg=1.8 satisfied the EIA-X7S (ΔC/C 25°C = ±22%, –55 °C to 125 °C) specification. X-ray photoelectron spectroscopy confirmed that Ho 3+ effectively captured oxygen vacancies by forming defect dipoles, while impedance spectroscopy demonstrated that the shell significantly inhibited carrier migration. Furthermore, the MLCCs device with Ho/Mg=1.8 exhibited a breakdown strength of 96.38 kV/mm and met the more stringent EIA-X7R (ΔC/C 25°C = ±15%, –55 °C to 125 °C) specification. These findings indicate that Ho/Mg co-doping effectively optimizes the core-shell structure, offering valuable theoretical guidance for developing MLCCs with enhanced temperature stability and reliability.