Enhancing dielectric properties of BaZrTiO ₃ via controlled anatase/rutile core‐shell TiO ₂

Abstract Numerous studies are being conducted to develop novel materials capable of achieving ultrahigh dielectric constants. In this research, we focused on controlling oxygen vacancies and grain growth in dielectric materials to enhance their dielectric properties. To achieve this, we successfully manipulated the crystal structure of TiO 2 in the perovskite structure using a core‐shell approach. This innovative method allowed us, for the first time, to regulate both oxygen vacancies and grain growth during solid‐state synthesis. After heat‐treating metastable anatase TiO 2 to form an anatase/rutile core‐shell structure, it was used as a precursor for Ba–Zr–TiO 3 solid‐state synthesis. At the optimal conditions for the anatase/rutile core‐shell (87% rutile and 13% anatase), the electron excitation in TiO 2 between the stable phase (rutile) and the metastable phase (anatase) generates localized Ti 3+ . The resulting oxygen vacancies induce the formation of electron‐pinned defect clusters, which are a significant cause of the ultrahigh dielectric constant in barium zirconate titanate.