Nickel–alumina nanocomposite powders prepared by novel in situchemical reduction

Nanocomposite powders of Ni–Al₂O₃ (5 and 10 vol% Ni) were prepared from porous alumina preforms with high specific area (100 m² g^?1) impregnated with nickel nitrate. Samples were obtained by reduction under a controlled oxygen partial pressure either directly or through an intermediate step, giving nickel aluminum spinel. In both cases, homogeneous dispersions of nickel particles in the alumina matrix were achieved. The Ni particle size ranged from 10 to 100 nm, depending on the preparation conditions and temperature.