BIMEVOX ceramics as an intermediate temperature SOFC electrolyte : another look

Titelangaben

Fuierer, Paul ; Ring, Kevin ; Exner, Jörg ; Moos, Ralf:
BIMEVOX ceramics as an intermediate temperature SOFC electrolyte : another look.
2015
Veranstaltung: 11th International Conference on Ceramic Materials and Components for Energy and Environmental Applications , 14.-19.06.2015 , Vancouver, Canada.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Vortrag )

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Abstract

Bismuth vanadate (Bi4V2O11) ceramics, stabilized by partial substitution of V5+ with transition metal (eg. Co, Cu, Ti) ions, exhibit high ionic conductivity and ionic transference number at temperatures below 500°C. For use as SOFC electrolyte, the ceramic has been dismissed by some due to reports of mixed conduction at higher temperature and low pO2. The 2-D conductivity of the oxide vacancies within the perovskite-like layers of the Aurivillius type structure also poses challenges. In the current study, select doping and unique processing schemes were used to produce near theoretical density and in some cases textured polycrystalline ceramics. Hot forging (HF) was used for bulk ceramics. Aerosol deposition (AD) was used for thick films. Bulk ceramics show high oxide ion conductivity (0.1 S/cm) at 500°C, with small anisotropy. Long term stability of the conductivity at temperature and low pO2 has been demonstrated. Measured thermal expansion (16-20 ppm/°C), also showing small anisotropy, may be compatible with metals in SOFC design. AD thick films deposited on alumina substrates are nano-crystalline, with a microstructure that appears to be stable to 500°C. Once annealed, the films have high conductivity over 0.01 S/cm, within an order of magnitude of the bulk. The results suggest that further investigation of BIMEVOX ceramics, for consideration as intermediate temperature SOFCs, is warranted.