Colossal dielectric behavior of (Ho, Ta) co‐doped rutile TiO2 ceramics

The dielectric properties of (Ho, Ta) co-doped rutile TiO2 (HTTO) ceramics with various dopant concentrations prepared by solid-state reaction method were investigated. The effect of (Ho, Ta) co-doping concentration on the microstructure and dielectric properties of the obtained ceramics were studied in detail. A high dielectric constant (3.35 × 104), low dielectric loss (0.021), and excellent frequency and temperature stability (-150–150 °C and 102–5⋅106 Hz) were achieved in an optimum composition of (Ho0.5Ta0.5)0.01Ti0.99O2. The origin of the colossal permittivity (CP) behavior of HTTO ceramics was discussed by XPS, XRD, SEM, and complex impedance spectroscopy. It was indicated that the high CP and low dielectric loss might be attributed to combined contribution of the internal barrier layer capacitance (IBLC) effect, electron-pinned defect-dipole (EPDD) effect, and electrode effect.