Spontaneous formation of an ordered interstratification upon Ni-exchange of Na-fluorohectorite

Abstract Interstratified structures are a common phenomenon in layered silicates and the differentiation between random and ordered interstratifications might be in some cases difficult. Atypical basal spacings observed for Ni-exchanged fluorohectorites could be related to such an ordered interstratified structure. Applying powder X-ray diffraction, thermal gravimetric analysis, and various spectroscopic techniques, an ordered interstratification of smectite-like [Ni(H2O)6]2+ and condensed, chlorite-like [Ni(OH)2−y(H2O)y]xy+interlayers, where x refers to the degree of condensation, was observed. By simple ion exchange a corrensite-like structure was obtained with a structural formula of {[Ni(OH)0.83(H2O)1.17]0.371.17+}Int. 1{[Ni(H2O)6]0.282+}Int. 2[Mg5Li] O20F4. Improving the contrast between the two distinct d-spacings and between the electron densities of the interlayers by partial ion exchange with a long chain alkylammonium cation or thermal annealing, helped to increase the intensity of superstructure reflections rendering the ordered interstratified structures more clearly visible.