This paper reports the preparation, microstructures and electrical properties of a Ni (55 vol%)/Sm-doped ceria cermet. A nickel powder of median size 14 μm or a NiO powder of median size 2.5 μm was mixed with Sm-doped ceria (SDC) powder (median size 0.87 μm) with a composition of Ce0.8Sm0.2O1.9, which was produced by the calcination of an oxalate solid solution (Ce0.8Sm0.2)2(C2O4)3 at 600°C. The mixtures of Ni/SDC (sample A) and NiO/SDC (sample B) were sintered at 1300°C in air to a relative density of 58.6% and 97.3%, respectively. During the sintering of the cermet, the Ni powder was oxidized to NiO in sample A. The NiO component in the as-sintered cermet was reduced to Ni in a H2-H2O atmosphere of an oxygen partial pressure ~10−20 atm at 700°C. Both the cermets showed a high stability of high electronic conduction to 100 h of heating at 700°C in a low oxygen partial pressure atmosphere. Sample A with large Ni particles was too brittle to handle after the heating. Sintering of the fine Ni grains in sample B proceeded at 700°C.

Keywords: Ni/Sm-doped ceria cermet, Anode material, Solid oxide fuel cell, Electronic conduction, Microstructure