Defect clusters and grain boundary induced giant dielectric response in (Nb+Bi) co-doped TiO2 ceramics

High dielectric loss and temperature-dependent dielectric constant are the main obstacles limiting the application of giant dielectric materials in microelectronic devices. Here, (Nb 0.5 Bi 0.5 ) x Ti 1- x O 2 (NBTO- x ) ceramics modified by defect cluster synergistic interfacial effects were designed to improve the dielectric properties, and the mechanism of the giant dielectric behavior was thoroughly investigated. The defect clusters formed by co-doping of Bi 3+ and Nb 5+ ions confined the free electrons to a limited range of jumps, leading to a significant increase in the dielectric constant and a decrease in the dielectric loss of the NBTO- x ceramics. Defect clusters aggregated near grain boundaries accumulated free electrons and carriers, which formed an interfacial effect with insulating grain boundaries, further reducing the dielectric loss. Thus, a high dielectric constant of 10 5 and a low loss of 0.04 at 1 kHz with a temperature stability of Δ ε′ / ε′ 25 °C ≤ ±15% (-55 °C to 105 °C) was obtained in the NBTO-0.5% ceramic. This study offers a new approach to the design of high-performing giant dielectrics with excellent potential for application in microelectronic devices.