Agglomeration behavior of nickel particles on YSZ and TiO2-doped YSZ electrolytes

Agglomeration behavior of nickel thin films on the yttria stabilized zirconia (YSZ) and TiO2 doped-YSZ electrolytes under a reducing condition and at solid oxide fuel cell (SOFC) operating temperatures was investigated by scanning electron microscopy (SEM) and scanning probe microscopy (SPM) to clarify whether this method is appropriate to investigate fundamental physicochemical properties that determine the microstructure of nickel/zirconia cermet anodes. Nickel agglomeration is enhanced with increasing annealing temperature and with decreasing the thickness of nickel films. Nickel agglomeration behavior was found to be essentially the same between YSZ and TiO2-doped YSZ electrolytes, forming small nickel particles with average diameter of less than 550 nm. Nonetheless, the effect by TiO2 doping to YSZ appeared for larger nickel particles formed due to enhancement in wettability of nickel metal on the electrolyte. It is demonstrated that the present method is actually an useful and powerful tool to investigate fundamental physicochemical properties in metal/oxide systems.

► Nickel agglomeration behavior on YSZ electrolyte is experimentally examined to validate an agglomeration analysis method proposed in the present study.
► Effects of TiO2 doping in the YSZ electrolyte are compared with that for YSZ by the proposed “agglomeration technique”.
► The energy balance of surface is different between small and large nickel particles on the TiO2 doped YSZ.