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A series of Ta5+ and La3+ co-doping TiO2 ceramics are prepared based on different annealing atmosphere and the traditional solid-state method. The crystal structure (XRD), SEM, EDS and dielectric properties are investigated based on the experiments. The rutile TiO2 as the host phase is conformed using the X-Ray Diffraction (XRD) patterns. The crystal structure of host phase is less affected by the annealing atmosphere for all the sintered ceramics. Meanwhile, the content of secondary phase in the sintered ceramics tends to reduce. In addition, the morphology of surface of all the sintered ceramics. The results indicate that O and Ti elements uniformly distribute on the regions of SEM, and the Ta and La elements exhibit shows aggregation phenomenon due to effects of the ionic radius and solid solubility. The measuring result of dielectric properties illustrate that all the sintered ceramics possess the colossal permittivity (εr) and low dielectric loss (tanδ). Besides, the dielectric constant is increased from 104 to 105, while the ceramic sample is processed utilize the atmosphere annealing method, which indicate the annealing atmosphere (N2 or N2/H2) can improve the dielectric properties. The frequency-dependent of dielectric properties Ta5+ and La3+ play an important role in colossal permittivity. Meanwhile, the behavior of colossal permittivity is attributed to the Electron Pinned Defect-Dipole (EPDD) effect.
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