"In situ" INVESTIGATION OF THE INTERMEDIATE STATE FORMED AT THE NiO/MoO³ REACTION INTERFACE. Boris P. Tolochko, Alexei V Bessergenev, Nikolay Z. Lyakhov, Vladimir Boldyrev, Sergei V.Chernov, *Sergei G. Nikitenko Institute of Solid State Chemistry, Novosibirsk-128, Russia *Institute of catalysis, Novosibirsk-90, Russia.

We planned to study the behavior of the Ni and Mo in the process of the NiMoO⁴ synthesis by new method - Simultaneous two energies anomalous scattering method ^[1]. We planned to receive information about position of the Ni in the Mo oxide at the initial stage of the reaction, about structure forming at the next stage and how it transforms to the [[alpha]]-NiMoO⁴.

EXAFS and XANES methods also used for the investigation of the crystal position of the Ni and Mo near NiO/MoO³ interface at the high temperature. The computational programs on the base of the self-consisting field Xa-multiple scattering wave method used for calculating of the XANES structures of Mo in the Na²MoO⁴, MoO³ and NiMoO⁴ and intermediate phase.

The diffraction date from Mo oxides near K-edge Ni received by the STEAS method during the solid state chemical reaction NiO+MoO³ at T=600-800 C. This method gives an anomalous scattering signal when the Ni atoms appear in the molybdenum oxide phase. At first stage of the interaction (at the interface) the small increasing d(060) of the MoO³ was observed. The kinetics of formation of intermediate phase obtained. At different temperatures the Ni atoms occupied different positions in the new structure, at 650 C they were at the sites of the crystal lattice, at 690 C they were in the interstitial positions.

The experimental data received by STEAS, EXAFS and XANES have show, that at the first stage is forming solid solution MoO³/NiO, than very quickly Mo4O11/NiO solution and then ß-NiMoO⁴.

1. A.V.Bessergenev, B. P.Tolochko, et al, in Nuclear Instruments and Methods in Physics Research, A 359(1995), pp 160-164.