Significantly enhanced dielectric properties of BaTiO3-based ceramics via synergetic grain size and defect engineering

As a dielectric material, BaTiO3-based ceramics are desirable for high performance ultra-thin multilayer ceramic capacitors (MLCCs) application. In this work, BaTiO3-based dielectric ceramics with superior dielectric properties were synthesized using a reducing atmosphere sintering process. It is found that the contribution of “wet" grain-boundary diffusion become significant as the oxygen partial pressure increases, resulting to a larger grain size and higher permittivity. Especially, for the specimen sintered in higher oxygen partial pressure, the stable temperature coefficient of capacitance (TCC) is dominated by irreversal domain due to the increase of super-lattice phase. Samples with higher oxygen partial pressure exhibit a higher permittivity of 2700 and better permittivity-temperature stability. Furthermore, ultra-thin MLCCs with thickness of 1 μm and capacitance of 10 μF and the TCC of X7R were successfully fabricated. This work provides a comprehensive explanation demonstrating upon the significant roles of grain size and defect engineering in the dielectric performance in BaTiO3-based ceramics, and points out an avenue to obtain excellent permittivity-temperature stability in ultra-thin MLCCs.