Giant interfacial polarization in TiO ₂ particles modified with defect dipoles

Multilayered ceramic capacitors (MLCCs) are demanded for miniaturized and large capacities with good reliability. To produce devices with desired properties, TiO 2 ‐based powder was co‐doped with 1 % Nb and 2.5 % Mg to achieve a giant dielectric permittivity while maintaining the same particle size. A 1 % Nb‐doped specimen heat‐treated at 1000°C for 4 h in a reducing atmosphere with log p O 2 = −17.7 and without Mg doping exhibited typical insulating behavior with low interfacial polarization. Mg doping remarkably increased the dielectric constant of the resulting material to approximately 10 4 ; however, it also increased its dielectric loss. The observed variations in the dielectric characteristics of the co‐doped TiO 2 powder with the Mg doping amount were attributed to changes in the density and mobility of electrons accompanying the changes in the Mg loading concentration within a single particle. The obtained material can potentially serve as the core material of a core–shell structure for MLCCs.