Influence of NiO on phase stabilization in 6 mol% yttria-stabilized zirconia

Yttria (6 mol%)-stabilized zirconia powders with addition of 0, 5 and 10 mol% NiO were prepared by means of radio frequency plasma synthesis. As-prepared and sintered (up to 1600°C) samples have been investigated by x-ray diffraction. The dissolution of NiO is found to enhance the formation of the cubic zirconia during plasma synthesis. Single-phase cubic zirconia solid solution forms if samples doped with 5 and 10 mol% NiO are heat treated at elevated temperatures. The cubic phase is stable at 1600°C, but undergoes a cubic-to-tetragonal phase transformation on cooling.