Abstract

Stabilized bismuth oxide material with fluorite structure (δ-Bi2O3) has been studied as a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to its high oxygen ion conductivity in mediate temperature. Especially; the ternary system Bi2O3–Er2O3–WO3 is widely concerned for its high ionic conductivity and thermal stability. In this study; regarding to its low melting point; the possibility to deposit dense Bi2O3–Er2O3–WO3 ((Bi2O3)0.705 (Er2O3)0.245 (WO3)0.05; EWSB) electrolyte by plasma spraying was examined. It was confirmed that the sintered EWSB bulk presents a high ion conductivity of 0.34 S cm-1 at 750 °C and excellent stability that indicates no structure transformation and conductivity degradation after annealing at 600 °C for 1000 h. The phase structure and cross-sectional microstructure of plasma-sprayed EWSB were characterized by XRD and SEM. Results showed that the as-plasma-sprayed EWSB presents a dense microstructure with well bonded lamellae. The XRD showed the formation of EWSB with δ-phase and a trace of β-phase; while the β-phase disappeared after annealed at 750°C for 10h. The deposited EWSB electrolyte presented the excellent ionic conductivity of 0.26 S cm-1 at 750 °C which can be directly applied to SOFC at intermediate temperature.

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