Study on conductivity and redox stability of iron orthovanadate

Cowin, Peter I. and Lan, Rong and Zhang, Lei and Petit, Christophe T. G. and Kraft, Arno and Tao, Shanwen (2011) Study on conductivity and redox stability of iron orthovanadate. Materials Chemistry and Physics, 126 (3). pp. 614-618. ISSN 1879-3312 (https://doi.org/10.1016/j.matchemphys.2011.01.009)

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Abstract

FeVO4 was synthesised by conventional solid state technique. Impedance measurements using a silver electrode were unsuccessful due to a solid state reaction between FeVO4 and Ag, forming alpha-AgVO3 and alpha-Fe2O3 at the interface. Impedance measurements, with a platinum electrode, reaffirmed that FeVO4 exhibits semiconductor behaviour in air. In a reducing atmosphere, 5% H-2/Ar, high electronic conductivity, from 1 S cm(-1) at 300 degrees C to 2 S cm(-1) at 700 degrees C, was observed with an activation energy of 0.13(1) eV. X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry data determined that the change in electronic conductivity was due to the degradation of the material into FeV2O4 and alpha-Fe2O3. It is believed that the conduction was due to electron hopping between vanadium d-orbitals. Neither FeVO4 nor FeV2O4 are deemed suitable as anode materials for solid oxide fuel cells, due to redox instability.

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