Improved mechanical properties and thermal expansion behavior of NiO–Y2O3 stabilized ZrO2 composite by addition of LaNbO4 for anode-support of planar solid oxide fuel cells

LaNbO 4 –NiO–Y 2 O 3 stabilized ZrO 2 (YSZ) composites are prepared and investigated as an anode-support material for solid oxide fuel cells. To tailor the coefficient of thermal expansion (CTE), electrical conductivity, fracture strength σ and fracture toughness K IC of the composite, various amounts of LaNbO 4 from 0 to 30   wt.% are added into 53   wt.% NiO–47   wt.% YSZ composite. With LaNbO 4 addition into the NiO–YSZ, σ changes insignificantly, whereas CTE decreases and K IC increases monotonously. For 30   wt.% LaNbO 4 –NiO–YSZ, the CTE is 12.4   ×   10 − 6   K − 1 (250–1000   °C), which is much closer to that of YSZ, and the K IC is 3.1   MPa-m 1/2 , which is 42% increase compared with that of the NiO–YSZ. The increase in fracture toughness is possibly due to the domain switch within LaNbO 4 and the overall grain refinement of the composite. The electrical conductivity of the reduced composites decreases with increasing the amount of LaNbO 4 and shows metallic conducting behavior with temperature.