Evaluation of Ni and Ti-doped Y2O3 stabilized ZrO2 cermet as an anode in high-temperature solid oxide fuel cells

The compatibility of nickel and Ti-doped 8 mol% Y2O3 stabilized ZrO2 (Ni-Ti-YSZ) cermets has been discussed for use as an anode in high-temperature solid oxide fuel cells (SOFC). The solubility limit of TiO2 in the YSZ fluorite was estimated to be at least 10 mol%. With increasing Ti content in the Ti-YSZ samples, the average linear thermal expansion coefficient was found to decrease when measured in an H-2 atmosphere. In an H-2 atmosphere, the oxygen vacancy concentration was observed to increase with increasing Ti content and temperature, and its value in the 8 mol% Ti-doped YSZ (8Ti-YSZ) sample was 0.0056 at 1000degreesC. Although electronic conduction appeared in the Ti-YSZ samples at temperatures greater than similar to600degreesC in the H-2 atmosphere, their electrical conductivities had a tendency to decrease with increasing Ti content. The mechanical strength of the Ni-Ti-YSZ cermets at room temperature were found to increase with increasing Ti content; Anodic polarization of the 40 vol.% Ni-8Ti-YSZ cermet at 1000degreesC was 60 mV at 300 mA cm(-2) in the H-2 atmosphere after firing at 1400degreesC for 10 h. (C) 2003 Elsevier Science B.V. All rights reserved.