Formability of metastable tetragonal solid solution in nanocrystalline NiO-ZrO2 powders

Nanocrystalline zirconia (ZrO2) powders doped with 10, 20, and 30 mol% nick el oxide (NiO) were prepared by chemical precipitation method. X-ray diffra ction (XRD) analysis reveals that the concentration of dopant NiO influence s the grain size and the variation in grain size seems to influence the for mation of the metastable tetragonal solid solution of NiO-ZrO2. Irrespectiv e of the dopant concentration, the as-prepared powders show only a monoclin ic phase even though the average grain size is less than the critical size for the tetragonal phase. This may be due to the dominance of the effect of lattice defects such as lattice strain. (C) 2000 Elsevier Science B.V. All rights reserved.