INTRA-LAYER AND INTER-LAYER STRUCTURES OF LAYERED HYDROXY DOUBLE SALTS, NI1-XZN2X(OH)(2)(CH3CO2)(2X)CENTER-DOT-NH(2)O

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 hydr othermally prepared precipitates, it was found that the brucite-type n ickel hydroxide is formed with partial nickel vacancies, and the zinc ions are stabilized in tetrahedral sites just below and above the nick el vacant sites in hydroxide planes, with three hydroxide and one acet ate ligands. The X-ray diffraction patterns indicate that the hydrothe rmally prepared precipitates exhibit an evolution of the interlayer di stance with respect to air-drying time at 25 degrees C, while such a c hange could not be observed for precipitates obtained by coprecipitati on. Such a different behavior arises from the difference in their posi tive layer charges and the contents of inserted acetate anion. From th e FT-IR spectroscopic study, it is concluded that the reversible struc tural 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.