Intra- and inter-layer structures of layered hydroxy double salts, Ni1-xZn2x(OH)2(CH3CO2)2x•nH2O

Layered nickel and zinc hydroxy double acetates have been prepared by both hydrothermal and coprecipitation methods. According to the X-ray absorption spectroscopic analyses at the Ni and Zn K-edge for the hydrothermally prepared precipitates, it was found that the brucite-type nickel hydroxide is formed with partial nickel vacancies, and the zinc ions are stabilized in tetrahedral sites just below and above the nickel vacant sites in hydroxide planes, with three hydroxide and one acetate ligands. The X-ray diffraction patterns indicate that the hydrothermally prepared precipitates exhibit an evolution of the interlayer distance with respect to air-drying time at 25 degrees C, while such a change could not be observed for precipitates obtained by coprecipitation. Such a different behavior arises from the difference in their positive layer charges and the contents of inserted acetate anion. From the FT-IR spectroscopic study, it is concluded that the reversible structural phase transformation is resulting from the change of orientation of intercalated acetates depending on the type of ligation, chelating or unidentate ones. (C) 1998 Elsevier Science B.V.