SIMULTANEOUS 2 ENERGIES ANOMALOUS SCATTERING FOR THE STUDY OF THE DYNAMICS OF STRUCTURAL TRANSFORMATION

In this work the wiggler of VEPP-3 is used for the generation of two b eams of synchrotron radiation. After the focusing monochromator, both beams have an energy near the Ni K-edge; they differ by 20 eV. At the sample position the two beams are separated by 2.3 mm. The simultaneou s registration of two X-ray diffraction patterns at different energies was made by two position sensitive detectors OD-2. A comparison of th e two diffraction patterns, registered at different energies, clearly shows the anomalous scattering effect for the test sample NiO. This me thod was used for the investigation of the behavior of the Ni atom dur ing the solid state chemical reaction NiO + MoO3 --> NiMoO4 at T = 600 -800 degrees C. This method gives an anomalous scattering signal when the Ni atoms appear in the molybdenum oxide phase. The kinetics of for mation of beta-NiMoO4 was obtained. At different temperatures the Ni a toms occupied different positions in the beta-NiMoO4 structure, at 650 degrees C they were at the sites of the crystal lattice, at 690 degre es C they were in the interstitial positions.