Study on conductivity and redox stability of iron orthovanadate

• Published in: Materials chemistry and physics Vol. 126; no. 3; pp. 614 - 618
• Main Authors: Cowin, Peter I., Lan, Rong, Zhang, Lei, Petit, Christophe T.G., Kraft, Arno, Tao, Shanwen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2011
• Subjects: Ceramics; Electrodes; Electronic materials; Electronics; Impedance measurement; Inorganic compounds; Oxide; Powder diffraction; Reducing atmospheres; Semiconductors; Silver; Solid oxide fuel cells; Solid state; Stability; Oxide; Electronic materials; Powder diffraction; Inorganic compounds; Ceramics
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2011.01.009

▶ FeVO 4 is not redox stable. ▶ Conductivity of FeVO 4 is high in a reducing atmosphere. ▶ FeVO 4 reacts with silver above 350 °C. ▶ FeVO 4 is not suitable as anode for solid oxide fuel cells. FeVO 4 was synthesised by conventional solid state technique. Impedance measurements using a silver electrode were unsuccessful due to a solid state reaction between FeVO 4 and Ag, forming α-AgVO 3 and α-Fe 2O 3 at the interface. Impedance measurements, with a platinum electrode, reaffirmed that FeVO 4 exhibits semiconductor behaviour in air. In a reducing atmosphere, 5% H 2/Ar, high electronic conductivity, from 1 S cm −1 at 300 °C to 2 S cm −1 at 700 °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 FeV 2O 4 and α-Fe 2O 3. It is believed that the conduction was due to electron hopping between vanadium d-orbitals. Neither FeVO 4 nor FeV 2O 4 are deemed suitable as anode materials for solid oxide fuel cells, due to redox instability.