Conductivity and redox stability of new double perovskite oxide Sr.sub.1.6K.sub.0.4Fe.sub.1+xMo.sub.1-xO.sub.6-δ

• Published in: Journal of materials science Vol. 51; no. 8; pp. 4115 - 4124
• Main Authors: Cowin, Peter I, Lan, Rong, Petit, Christophe T. G, Wang, Huanting, Tao, Shanwen
• Format: Journal Article
• Language: English
• Published: Springer 01.04.2016
• Subjects: Electric properties; Electrical conductivity; Oxides; Perovskite
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-016-9734-9

A series of new perovskite oxides Sr.sub.1.6K.sub.0.4Fe.sub.1+xMo.sub.1-xO.sub.6-δ (x = 0.2, 0.4, 0.6) were synthesised by solid state reaction method. Synthesis of Sr.sub.1.6K.sub.0.4Fe.sub.1+xMo.sub.1-xO.sub.6-δ (x = 0.2, 0.4, 0.6) was achieved above 700 °C in 5 % H.sub.2/Ar, albeit with the formation of impurity phases. Phase stability upon redox cycling was only observed for sample Sr.sub.1.6K.sub.0.4Fe.sub.1.4Mo.sub.0.6O.sub.6-δ. Redox cycling of Sr.sub.1.6K.sub.0.4Fe.sub.1+xMo.sub.1-xO.sub.6-δ (x = 0.2, 0.4, 0.6) demonstrates a strong dependence on high temperature reduction to achieve high conductivities. After the initial reduction at 1200 °C in 5 %H.sub.2/Ar, then re-oxidation in air at 700 °C and further reduction at 700 °C in 5 %H.sub.2/Ar, the attained conductivities were between 0.1 and 58.4 % of the initial conductivity after reduction 1200 °C in 5 %H.sub.2/Ar depending on the composition. In the investigated new oxides, sample Sr.sub.1.6K.sub.0.4Fe.sub.1.4Mo.sub.0.6O.sub.6-δ is most redox stable also retains reasonably high electrical conductivity, ~70 S/cm after reduction at 1200 °C and 2-3 S/cm after redox cycling at 700 °C, indicating it is a potential anode for SOFCs.