The "In Situ" Research of the Synthesis of NiMoO4

Abstract

The formation of the crystal structure of the NiMoO4 high temperature phase the solid phase reaction NiO+α-MoO3→β-NiMoO4 at 600 C has been in situ studied with the high temperature synchrotron technique. We have performed the measurements of the Extended X-ray Absorption Fine Structure (EXAFS) and the X-ray Absorption Near Edge Structure (XANES) at the K-edge of Ni atom during the -niMoO4synthesis. The 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 the final production reaction has got an unique geometry that differs from the octahedral oxygen surrounding of Ni atoms the both structures of NiO and β-NiMoO4. At the initial stage of the β-NiMoO4 synthesis there is not the final product of the synthesis, but the formation of the β-NiMoO4 crystal structure takes place essentially later, contrary to how it has been considered so far. We have concluded that at the original stage of the β-NiMoO4 synthesis the some intermediate phase is formed that is characterized with the low concentration of nickel and the low symmetrical geometry for the nearest oxygen surrounding of Ni atoms.