FORMATION OF EXPANDABLE MICA FROM TALC USING THE INTERCALATION PROCEDURE

To investigate the transformation process from talc to expandable mica s, mixtures of talc and Na2SiF6 were heated from 600 degrees to 900 de grees C and air-quenched at 50 degrees C intervals, The air-quenched p roduct at 800 degrees C mainly consisted of expandable micas with a ba sal spacing of 1.25 nm, nonexpandable materials with a basal spacing o f 0.96 nm, and a small amount of talc used as the starting material, A lattice fringe image by HRTEM of the product shows that the layer spa cing at the edges surfaces is about 1.2 nm, but the layer spacing insi de of the particles is close to that of talc, Such a nanostructure ind icates a topotactic reaction from talc to expandable micas and confirm s that Na+ ions intercalate into the structure from the edge to the co re.