INTERACTION OF NIO WITH YTTRIA-STABILIZED ZIRCONIA

As-prepared and heat treated plasma-produced 8 and 10 mol% yttria-stab ilized zirconia (YSZ) powders doped with 0, 5, 10 and 75 mol% NiO have been investigated by XRD. The as-prepared powders are mixtures of met astable tetragonal and cubic phases but they transform to a single YSZ phase upon heat treatment above 1200 degrees C. The solubility of NiO in yttria-stabilized zirconia is less than 2 mol% at 1600 degrees C a nd varies little within the investigated yttria concentration range. T he solubility increases with increasing temperature and the total NiO concentration. The activation energy of the solubility is about 0.25 e V.