Conductivity and redox stability of new perovskite oxides SrFe0.7TM0.2Ti0.1O3-δ (TM = Mn, Fe, Co, Ni, Cu)

Cowin, Peter Ian and Lan, Rong and Petit, Christophe T. G. and Du, Dongwei and Xie, Kui and Wang, Huanting and Tao, Shanwen (2017) Conductivity and redox stability of new perovskite oxides SrFe0.7TM0.2Ti0.1O3-δ (TM = Mn, Fe, Co, Ni, Cu). Solid State Ionics, 301. pp. 99-105. ISSN 0167-2738

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    Abstract

    New perovskite oxides SrFe0.7TM0.2Ti0.1O3-δ (TM = Mn, Fe, Co, Ni, Cu) were synthesised by sol-gel processes. Their redox stability and conductivity in both air and 5%H2/Ar were investigated in details. The cubic perovskite structure was also observed for all dopants with variation in the lattice parameters associated with different dopant environments and charge compensation mechanisms. Improvement of the electronic conductivity over SrFe0.9Ti0.1O3-δ was observed for all dopants in air, attributed to increasing charge carrier concentrations. Reduction in 5% H2/Ar exhibited minimal a material properties for SrFe0.7Cu0.2Ti0.1O3-δ, with a significant reduction in conductivity was observed for SrFe0.7Mn0.2Ti0.1O3-δ. All doped compounds exhibited a single phase cubic perovskite structure after reduction in 5%H2/Ar at 700 °C with the exception of SrFe0.7Ni0.2Ti0.1O3-δ and SrFe0.7Co0.2Ti0.1O3-δ which displays secondary nickel and cobalt phases respectively upon reduction. SrFe0.7Cu0.2Ti0.1O3-δ is redox stable at a temperature below 700 °C and highly conductive with conductivities around 10 S cm− 1 in both air and reducing atmosphere which are about five times higher than those of pure SrFe0.9Ti0.1O3-δ. In terms of conductivity and redox stability, it is a potential redox stable electrode material for reversible and symmetrical solid oxide fuel cells as well.