Oxygen-conducting Composites Based on Me2(WO4)3 (Me = Sm, Al)

Abstract

Composites Sm2(WO4)3-WO3 and Al2(WO4)3-WO3 were prepared by the solid-state method and a systematic study of their electrotransport properties has been carried out. A sharp increase in the oxygen-ion conductivity is observed in composites Sm2(WO4)3–WO3 at small WO3 values (about 10 mol.%). This effect is probably caused by formation of the non-autonomous interface phase covering grain boundaries of Sm2(WO4)3. These composite O2− – electrolytes are perspective materials for high temperature fuel cells. Тhe composite effect is absent in the Al2(WO4)3–WO3 system. This is probably due to the negative thermal expansion coefficient of Al2(WO4)3, which prevents the formation of a continuous high-conducting microphase film.


Keywords: composites, ionic conductivity, heterogeneous doping, microphase

References
[1] Ishihara, T. (2009). Perovskite Oxide for Solid Oxide Fuel Cells, p. 302. Boston, MA: Springer.


[2] Tarancón, A. (2009). Strategies for lowering Solid Oxide Fuel Cells operating temperatures. Energies, vol. 2, pp. 1130–1150.


[3] Neiman, A. Ya., Pestereva, N. N., Sharafutdinov, A. R., et al. (2005). Conduction and transport numbers in metacomposites MeWO4–WO3 (Me = Ca, Sr, Ba). Russian Journal of Electrochemistry, vol. 41, no. 6, pp. 598–611.


[4] Neiman, A. Ya., Uvarov, N. F., and Pestereva, N. N. (2007). Solid state surface and interface spreading: An experimental study. Solid State Ionics, vol. 177, pp. 3361– 3369.


[5] Pestereva, N., Zhukova, A., and Neiman, A. (2007). Transport numbers and ionic conduction of eutectic methacomposites {(1–x)MeWO4–xWO3} (Me=Sr, Ba; x=0- 0.55). Russian Journal of Electrochemistry, vol. 43, no. 11, pp. 1305–1313.


[6] Pestereva, N. N., Safonova, I. G., Nokhrin, S. S., et al. (2010). Effect of MWO4 (M = Ca, Sr, Ba) dispersion on the interfacial processes in (+/–)WO3|MWO4|WO3(–/+) cells and transport properties of metacomposite phases. Zhurnal Neorganicheskoi Khimii, vol. 55, no. 6, pp. 876–882.


[7] Neiman, A. Ya., Pestereva, N. N., Zhou, Y., et al. (2013). The nature and the mechanism of ion transfer in tungstates Me2+{WO4} (Ca, Sr, Ba) and Me2 3+{WO4}3 (Al, Sc, In) according to the data acquired by the tubandt method. Russian Journal of Electrochemistry, vol. 49, no. 9, pp. 895–907.


[8] Pestereva, N., Guseva, А., Vyatkin, I., et al. (2017). Electrotransport in tungstates Ln2(WO4)3 (Ln = La, Sm, Eu, Gd). Solid State Ionics, vol. 301, pp. 72–77.