Preparation and Properties of Cobalt(II) Hydroxide–(Sodium Fluoride Tetrasilicic Mica) Intercalation Complexes and of Highly Dispersed Cobalt on Mica

Abstract Cobalt(II) hydroxide–(sodium fluoride tetrasilicic mica) intercalation complexes were prepared by titrating cobalt(II) nitrate solutions in the presence of mica with sodium hydroxide under oxygen-free conditions. These complexes were characterized by chemical analysis, XRD, DTA-TGA, IR, and surface area measurements. These confirmed that the brucite-like cobalt(II) hydroxide sheet developed within the interlayer of the silicate. Cobalt atoms reduced at 400–700 °C by H2 migrated from the interlayer of the silicate to the external surface of these where highly dispersed cobalt particles were formed. Ultra-fine cobalt metals (50–200 Å) with a hexagonal close-packed form were prepared at 400 °C by H2. The degree of reduction and the grain diameter of cobalt increased with an increase of the reducing temperature and/or the reducing time.