Colossal Permittivity and Ultra-Low Dielectric Loss Realized in In/Nb Co-Doped TiO2 Ceramics by Oxygen Vacancy Tailoring

TiO 2 -based colossal permittivity ceramics with high dielectric constant and low loss have become one of the key candidates for high-capacity high-end capacitors. This study investigates the influence of oxygen vacancy concentration on the dielectric properties of TiO 2 -based ceramics by adjusting the acceptor-to-donor ratio, and finds that the (In x Nb 1− x ) 0.005 Ti 0.995 O 2 (INTO) sample with x = 1/3 exhibits ultra-low dielectric loss (tan δ) of 0.013 as well as high dielectric constant ( ε r ) of 1.7 × 10 4 (1 kHz). The results obtained from dielectric property measurements, relaxation behavior analysis, and X-ray photoelectron spectroscopy indicate that the high dielectric constant and low dielectric loss originate from the synergistic effect between oxygen vacancy-related defect clusters and electron-pinned defect dipoles. This work not only provides a new strategy for achieving colossal permittivity and ultra-low loss simultaneously via oxygen vacancy tailoring in TiO 2 -based ceramics and related materials, but also develops promising candidates for high-capacitance ceramic capacitors.