Colossal permittivity in TiO2 ceramics modified by Ta and Zn

Zn and Ta co-doped TiO 2 ceramics with the nominal composition (Zn 1/3 Ta 2/3 ) x Ti 1-x O 2 ) were prepared using a conventional solid-state reaction method. Phase analysis revealed that all samples consisted of a single rutile-type TiO 2 phase, exhibiting a dense microstructure and uniform grain size. At a doping level of x = 0.005, the material exhibited excellent dielectric properties. Specifically, at room temperature and 1 kHz, its dielectric permittivity reached 3.93 × 10 4 , with a dielectric loss of 0.031. Over the temperature range from −60 °C to 200 °C, the variation in the dielectric permittivity was less than 15%, while the dielectric loss remained below 0.02 between −60 °C and 112 °C. X-ray photoelectron spectroscopy (XPS) was employed to analyze the valence states of the constituent elements. Impedance spectroscopy and bias-voltage measurement, together with the XPS analysis, revealed the coexistence of multiple mechanisms in Zn and Ta co-doped TiO 2 ceramics Electron-pinned defect-dipole (EPDD) polarization was identified as the primary origin of the colossal dielectric behavior, while Maxwell-Wagner polarization also contributed to the dielectric response.