Niobium-doped strontium titanates as SOFC anodes

• Sr-vacancy compensated Nb-doped SrTiO3 with the nominal composition Sr0.94Ti09Nb0.1O3 has been evaluated as part of a solid oxide fuel cell (SOFC) anode material in terms of redox stability, electrical conductivity, as well as electrochemical properties. Sr0.94Ti0.9Nb0.1O3 has been synthesized with a recently developed modified glycine-nitrate process. The synthesized powders have been calcined and sintered in air or in 9% H 2 / N2 between 800 - 1400 °C After calcination the samples were single phase Nb-doped strontium titanate with grain sizes of less than 100 nm in diameter on average. The phase purity, defect structure, and microstructure of the materials have been analyzed with SEM, XRD, and TGA. The electrical conductivity of the Nb-doped titanate decreased with increasing temperature and showed a phonon scattering conduction mechanism with σ > 120 S/cm at 1000 °C (in 9 % H2 / N2). The electrochemical properties of Sr0.94Ti0.9Nb 0.1O3 and a composite electrode of Sr 0.94Ti0.9Nb0.1O3/YSZ have been investigated by using a symmetrical cell configuration. The tests indicated that the electrodes were redox stable and showed a potential ability of the Nb-doped titanates to be used as a part of a SOFC anode. However, the catalytic activity of the materials was not sufficient and it needs to be improved if titanate based materials are to be realized as constituents in SOFC anodes.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Keramteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Ceramics (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

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