Microstructure and dielectric properties of (Nb plus In) co-doped rutile TiO2 ceramics

作者：Li Jinglei; Li Fei^*; Zhuang Yongyong; Jin Li; Wang Linghang; Wei Xiaoyong; Xu Zhuo; Zhang Shujun

来源：Journal of Applied Physics, 2014, 116(7): 074105.

DOI：10.1063/1.4893316

• Annealing treatments
• Colossal dielectrics
• Effect of annealing
• High activation energy
• Impedance spectroscopy
• Low dielectric loss
• Semiconducting grains
• Solid state reaction method

The (Nb + In) co-doped TiO2 ceramics recently attracted considerable attention due to their co-lossal dielectric permittivity (CP) (similar to 100,000) and low dielectric loss (similar to 0.05). In this research, the 0.5mol.% In-only, 0.5mol.% Nb-only, and 0.5-7mol.% (Nb + In) co-doped TiO2 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 Ti4+ ions to Ti3+ 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 TiO2 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 TiO2 ceramics. Compared with CaCu3Ti4O12 ceramics, the high activation energy of co-doped rutile TiO2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.

• 出版日期2014-8-21
• 单位西安交通大学