Effect of BaO addition on core-shell structure and electric properties of BaTiO3-based dielectrics for high-end MLCCs

Core-shell structured fine grain dielectrics, featured with high dielectric constant and wide temperature stability, are essential for the production of high-end MLCCs. In this work, the core-shell structured 100BaTiO3-xBaO-2.4MgO-1.0ZrO2-0.03MoO3-2.25Y2O3-0.3MnO2-2.0SiO2 (x = 0.5, 1.0, 1.5, 2.0, 3.0, 4.0) ceramics were prepared and the effects of BaO additions on the microstructure and dielectric properties were studied. The resulting ceramics exhibited fine grains (average size 280–300 nm) and demonstrated a high dielectric constant (>1780). Notably, the core-shell structure of the ceramics was affected by the BaO content, with the core volume gradually increasing as the BaO addition grew. This adjustment in composition was found to enhance the temperature stability and reliability of the materials. When the BaO addition reaches 4.0 mol%, the values of ΔC150/C25 °C were effectively suppressed from −22 % to −10.3 % to meet the X8R specification, and the insulation resistivity increased by more than an order of magnitude, reaching a maximum of 11.6 × 1012 Ω m. Our findings highlight the potential of BaO as an effective additive for enhancing the dielectric properties of core-shell structured fine grain dielectrics for high-end MLCCs.