Preparation, characterization, and giant dielectric permittivity of (Y3+ and Nb5+) co–doped TiO2 ceramics

Abstract

The microstructure and giant dielectric properties of Y3+ and Nb5+ co–doped TiO2 ceramics prepared via a chemical combustion method are investigated. A main rutile–TiO2 phase and dense ceramic microstructure are obtained in (Y0.5Nb0.5)xTi1-xO2 (x=0.025 and 0.05) ceramics. Nb dopant ions are homogeneously dispersed in the microstructure, while a second phase of Y2O3 particles is detected. The existence of Y3+, Nb5+, Ti4+ and Ti3+ as well as oxygen vacancies is confirmed by X–ray photoelectron spectroscopy and X–ray absorption near edge structure analysis. The sintered ceramics exhibit very high dielectric permittivity values of 104–105 in the frequency range of 40–106Hz. A low loss tangent value of ≈0.08 is obtained at 40Hz. (Y0.5Nb0.5)xTi1-xO2 ceramics can exhibit non–Ohmic behavior. Using impedance spectroscopy analysis, the giant dielectric properties of (Y0.5Nb0.5)xTi1-xO2 ceramics are confirmed to be primarily caused by interfacial polarization.