Dielectric response of TiO2 ceramics: The crucial role of Ta2O5.

Colossal permittivity in tantalum-doped TiO 2 (Ta x Ti 1− x O 2 ) ( x = 1%, 2%, 3%, 4%, 5% and 6%) fabricated by the conventional solid-state reaction method in N 2 atmosphere were achieved. Especially, by optimizing components and sintering temperatures, the dielectric loss could significantly decreased. The effects of Ta doping on their microstructure, dielectric properties, and temperature stability were revealed in detail. When the composition with x = 5% and sintered at 1400 °C, the dielectric constant reached to ∼30000 and the dielectric loss decreased to 3%. Interestingly, all the samples also exhibit good temperature stability of dielectric properties in a wide temperature range from 100 to 350 K. Based on XPS analysis, the formation of defect-dipole clusters, e.g. 2 ( Ta 5 + ) Ti · → 4 ( Ti 3 + ) Ti ′ ← V o ·· should be mainly responsible for the improved dielectric properties in tantalum-doped TiO 2 . [ABSTRACT FROM AUTHOR]