Colossal permittivity of (Mg + Nb) co-doped TiO2 ceramics with low dielectric loss

Abstract

A high dielectric loss is one of the difficulties that hinder the application of colossal permittivity (CP) materials. Here we report the CP behaviors in ceramics of rutile (Mg + Nb) co-doped TiO₂, i.e., (Mg_1/3Nb_2/3)_xTi_1−xO₂. The room-temperature dielectric properties of the pure homogenous ceramics include a relatively high CP (>10⁴) and an acceptable dielectric loss (<0.1) at frequencies from 10² to 10⁵ Hz in the doping concentration range of 0.5% to 7%. In particular, an excellent low dielectric loss of 0.0083 and a high dielectric permittivity of 3.87 × 10⁴ at 1 kHz were obtained for the 1% doped sample. Moreover, the temperature stability (room temperature ∼ 180 °C) and frequency stability (10²–10⁵ Hz) of the CP properties were studied. X-ray photoelectron spectroscopy suggests that the superior CP properties could be explained by the electron-pinned defect-dipole mechanism.