LaNbO 4 –NiO–Y 2 O 3 Stabilized ZrO 2 Anode‐Support Materials for Solid Oxide Fuel Cells

As anode‐support materials for solid oxide fuel cells, porous LaNbO 4 –NiO–Y 2 O 3 stabilized ZrO 2 ( YSZ ) composites ( LNY ), containing 0, 5, 10, 15, and 20 wt% of LaNbO 4 and designated as 0 LNO , 5 LNO , 10 LNO , 15 LNO , and 20 LNO , respectively, are prepared by tape casting and sintering. They are investigated for their microstructure and mechanical, electrical and thermal expansion properties. The porosity of as‐sintered LNY is around 30%, and that of reduced LNY cermets decreases from 47% for reduced 0 LNO to 43% for reduced 20 LNO . The fracture strength (σ f ) of LNY is higher than that of the reduced form; however, both of them are not rather sensitive to the amount of LaNbO 4 , depending on crack‐originating flaws in the specimens. The fracture toughness ( K IC ) of LNY increases with LaNbO 4 content and is 1.87 MPa·m 1/2 for 20 LNO , which is more than 20% increase from that of 0 LNO ; however the K IC for reduced LNY is higher than that of LNY , and decreases with increasing LaNbO 4 content due to the decreased amount of ductile metallic Ni phase. The conductivity of reduced LNY depends on Ni content and is higher than 289 S/cm at temperatures below 900°C. The coefficient of thermal expansion ( CTE ) of both LNY and reduced LNY is in the range between 12.4 and 11.4 × 10 −6  K −1 ; which is closely matched with that of YSZ electrolyte.