Titania doped YSZ for SOFC anode Ni-cermet

The influence of doping YSZ (8 mol%YttriaStabilizedZirconia) with 5 and 10 mol% TiO₂ on the electrical conductivity and the microstructure was examined for different YSZ-Ni cermets as a function of Ni-content. For the 5 mol%TiO₂-doped cermets the electrical conductivity was always better than that of the undoped, exhibiting a lower degradation rate at 1000 °C. Microstructure examination of the samples showed a lower tendency for agglomeration of the Ni-particles of the doped cermets compared to the Ni/YSZ cermet. The 10 mol%TiO₂-doped cermets exhibited lower conductivity values and this was attributed to the significantly higher porosity which resulted from a reaction taking place during sintering between the insoluble TiO₂ in YSZ and NiO. This reaction results in the formation of a NiO-TiO₂ spinel phase, which leads to the expansion of the samples causing microstructural defects. Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.