Reduction of interlayer Co2+ ions in fluorine mica using diethylene glycol

Reduction of interlayer Co2+ ions in expandable fluorine mica has been attempted. The polyol process using diethylene glycol as a reducing agent was employed. The Co2+ -exchanged mica was refluxed at about 225-235 degrees C in liquid diethylene glycol for 10-120 minutes. Consequently, zero-valence Co metal (Co-0) intercalated mica having a metallic grey colour was obtained by in situ reduction of interlayer Co2+ ions, showing different properties from Co2+ -exchanged mica as a precursor. The layer charge of Co-metal-intercalated mica is compensated by protons which are produced through the course of reduction of interlayer Co2+ ions. The reduced sample heated at 350 degrees C, which had no organic molecules, exhibited a basal spacing of 1.28 nm, indicating the presence of 0.34 nm cobalt metal clusters after subtracting the thickness of the host silicate layer. During the process of reduction in diethylene glycol, cobalt metal particles were expelled from the interlayers which grew to about 0.5 mu m onto the external surfaces of host mica crystals with increasing refluxing time. (C) 1998 Chapman & Hall.