Correlation between the radius of acceptor ion and the dielectric properties of co-doped TiO2 ceramics

There is an urgent need to seek colossal dielectric materials with better dielectric properties because of the rapid development of the electronics industry. In this work, (M_0.5Nb_0.5)_0.01Ti_0.99O₂ (M = Al, In, Eu) ceramics are synthesized by traditional solid-state reaction, and recorded as ANTO, INTO and ENTO ceramics, respectively. The effects of different radius acceptor ions on the phase structure, microstructure and dielectric properties of TiO₂ based ceramics are investigated. It is found that all samples are rutile phases without the generation of the second phase, but the difference of ion radius resulted in lattice distortion of different degrees, which affects the defect structure in the material. The dielectric properties of the materials are related to the defect structure in the material, and the ability to localize electrons in different defect structures is different. The dielectric properties of ANTO ceramics are similar to those of un-doped TiO₂; INTO ceramics have the lowest dielectric loss (0.039), the best temperature and frequency stability, and there are no dielectric loss peak near the room temperature; The ENTO ceramics has the maximum permittivity (2.01 × 10⁵).