The Enhanced Stabilization of the Cubic Phase in Yttria‐Stabilized Zirconia with the Addition of Nickel Oxide

The influence of NiO on the stabilization and microstructure of yittria (Y 2 O 3 )‐stabilized zirconia (ZrO 2 ) (YSZ) is examined. Cold‐pressed powders comprising varying amounts of NiO, 8 mol%Y 2 O 3 , and ZrO 2 were sintered at 1500°C for 4 h. Specimens were subsequently given a 100 h heat treatment at 1500°C. Phase analysis by X‐ray diffraction revealed that the presence of NiO leads to a greater amount of cubic phase ZrO 2 for the sintered specimens compared with the control specimens. The cubic ZrO 2 lattice parameter was significantly smaller for specimens containing NiO, revealing that Ni 2+ ions likely enter the cubic ZrO 2 lattice and play a role in decreasing the time and temperature required for stabilization of the cubic phase. A spherical diffusion model was used to estimate the diffusion of Y 3+ and Ni 2+ into ZrO 2 . These results are discussed in the context of the role of NiO in the synthesis of YSZ.