LaNbO4 toughened NiO–Y2O3 stabilized ZrO2 composite for the anode support of planar solid oxide fuel cells

NiO–Y2O3 stabilized ZrO2 (YSZ) composite is the state-of-the-art material for the anode support of planar solid oxide fuel cells (SOFCs). To improve its fracture toughness (KC), lanthanum orthoniobate LaNbO4 is synthesized by the method of solid state reaction and added to the mixture of YSZ and NiO at the weight ratio of 47:53. The content of LaNbO4 in the composite is in the range between 5 and 30 wt%. The microstructure of the composites is examined by scanning electron microscopy (SEM); and the chemical compatibility among the components is evaluated by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Vickers hardness test is performed for estimating the KC of the composites. The results indicate that the KC increases with the addition of LaNbO4 in the composites; and the toughening effect is associated with the grain-refinement in the composite and the domain switch in the monoclinic LaNbO4.