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

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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.