THE IN-SITU RESEARCH OF THE SYNTHESIS OF NIMOO4

The formation of the crystal structure of the NiMoO4 high temperature phase in the solid phase reaction NiO+alpha-MoO3-->beta-NiMoO4 at 600 C has been ''in situ'' studied with the high temperature synchrotron t echnique. We have performed the measurements of the Extended X-ray Abs orption Fine Structure (EXAFS) and the X-ray Absorption Near Edge Stru cture (XANES) at the K-edge of Ni atom in during the beta-NiMoO4 synth esis. Tile analysis of the XANES data and the Fourier transformants of the EXAFS data has led us to the conclusion that at the initial stage of synthesis the nearest oxygen surrounding of Ni atoms in the final production reaction has got an unique geometry that differs from the o ctahedral oxygen surrounding of Ni atoms in the both structures of NiO and beta-NiMoO4. At the initial stage of the beta-NiMoO4 synthesis th ere is not the final product of the synthesis, bur the formation of th e beta-NiMoO4 crystal structure takes place essentially later, contrar y to how it has been considered so far. We have concluded that at the original stage of the beta-NiMoO4 synthesis the some intermediate phas e is formed that is characterized with the low concentration of nickel and the low symmetrical geometry for the nearest oxygen surrounding o f Ni atoms.