Boosting effective capacitance of nanograined BaTiO3-based ceramics via a precise core-shell-structure optimization strategy

The continued miniaturization of multilayer ceramic capacitors (MLCCs) means that thinner dielectric layers are exposed to stronger electric fields, degrading their capacitance. Thus, improving the DC-bias stability is urgent to maintain capacitance under strong electric fields and satisfy the requirements of high-end MLCCs. This work proposes a strategy for optimizing the DC-bias performance by tuning the core-shell structure of ceramics. Both numerical and experimental results indicate that the DC-bias performance of core-shell-structure ceramics can be significantly optimized under the double action of thickening the shell and increasing the shell dielectric constant, which simultaneously achieves considerable dielectric constant under DC-bias. Dy-Mg co-doped BaTiO3-based ceramics with an average grain size of about 180 nm prove extremely DC-bias stability and have a high dielectric constant of about 2000 and a low DC-bias attenuation coefficient of −23.6% at 4 kV/mm, which guarantees a high effective capacitance, especially under high electric fields.