High-conducting Bi4V2_ xFexO11-d ceramics containing Fe2O3 nanocrystals: Structure and properties

The topography, structure, thermal, magnetic, and electrical properties of Bi4V2_ xFexO11-delta ceramics substituted with x = 0.5 and 0.7 Fe were studied. The microscope analysis showed the presence of iron-rich nanocrystals formed on the Bi-Fe-V-O grains. The X-ray diffraction studies confirmed that grains are built mostly of tetragonal Bi4V1.5Fe0.5O10.5 phase. Thermal properties analysis showed an order-disorder type gamma ? gamma? phase transition at a temperature of around 916 K, pronounced in samples doped with x = 0.5 Fe. The magnetic anomaly was observed in ceramics doped with x = 0.7 Fe which was assigned to Morin transition of Fe2O3. The conductivity was measured over a wide frequency range from 10 mHz to 1 MHz and at a wide temperature range from 373 to 923 K, using impedance spectroscopy. The D.C. conduction process was due to oxygen vacancies hopping while at low temperatures electron holes hopping is also possible.

Automated summary

In this study, the topography, structure, thermal, magnetic, and electrical properties of Fe-doped Bi4V2_xFexO11-delta ceramics were investigated. It was found that iron-rich nanocrystals formed on the Bi-Fe-V-O grains, and the grains were mainly composed of tetragonal Bi4V1.5Fe0.5O10.5 phase. Different phase transitions and magnetic anomalies were observed in ceramics doped with different Fe concentrations, and the conductivity measurements revealed different conduction mechanisms at different temperature ranges.