Cu(II)-intercalated muscovite: An infrared spectroscopic study

Diffuse reflectance infrared spectroscopy (DRIFT) has proved to be a useful tool for the investigation of migration paths of intercalated metal cations within the layered structure of phyllosilicates like muscovite. While the fixation of small cations like lithium or copper in clay minerals and their migration paths have been studied extensively, they never have been reported for muscovite. Therefore, the aim of this study was to investigate the effects of a treatment with a supersaturated Cu-nitrate solution on the structure of muscovite. Additional X-ray diffractometric (XRD) data showed the formation of new d(0 0 l) and d(0 0 2) peaks, and thus proved that the new cations already were intercalated into the muscovite interlayers, although the concentration of the original interlayer cation potassium was nearly not affected. This suggested the simultaneous occurrence of both potassium and copper in the interlayers, resulting in an expansion along the c-axis and in a decrease of the a and b parameters. The spectroscopic investigations proved a migration of the cations deep into the tetrahedral sheets. As all bands which can be assigned to vibrations of the octahedral sheet (e.g. at 713 or 903 cm−1) were strongly affected by the treatment, a fixation of Cu close to the OH-groups of the octahedral sheets was suggested.