Publication Date:
2014-08-19
Description:
The (Nb + In) co-doped TiO 2 ceramics recently attracted considerable attention due to their colossal dielectric permittivity (CP) (∼100,000) and low dielectric loss (∼0.05). In this research, the 0.5 mol. % In-only, 0.5 mol. % Nb-only, and 0.5–7 mol. % (Nb + In) co-doped TiO 2 ceramics were synthesized by standard conventional solid-state reaction method. Microstructure studies showed that all samples were in pure rutile phase. The Nb and In ions were homogeneously distributed in the grain and grain boundary. Impedance spectroscopy and I-V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The high conductivity of grain was associated with the reduction of Ti 4+ ions to Ti 3+ ions, while the migration of oxygen vacancy may account for the conductivity of grain boundary. The effects of annealing treatment and bias filed on electrical properties were investigated for co-doped TiO 2 ceramics, where the electric behaviors of samples were found to be susceptible to the annealing treatment and bias field. The internal-barrier-layer-capacitance mechanism was used to explain the CP phenomenon, the effect of annealing treatment and nonlinear I-V behavior for co-doped rutile TiO 2 ceramics. Compared with CaCu 3 Ti 4 O 12 ceramics, the high activation energy of co-doped rutile TiO 2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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