J. Phys. IV France 7 (1997) C2-179-C2-181
Identification of Atom Displacement Directions in ABO3 Compounds by EXAFSL. Bugaev1, V. Shuvaeva1, I. Alekseenko1, K. Zhuchkov2 and E. Husson3
1 Department of Physics, Rostov University, Zorge. str. 5, Rostov-on-Don 344090, Russia
2 Department of Physics, Rostov University, Zorge. str. 5, Rostov-on-Don 344090 Russia
3 LPMM, ESEM, Université d'Orléans, 45072 Orléans cedex 2, France
Ab initio simulations of Nb K-XAFS in crystals with well known structures - LiNbO3, NaNbO3 at T=300 K, rhombohedral KNbO3 and the analysis of their Fourier-transformants (FT) permit to propose the probe for identification of Nb displacements from the centre of oxygen-octahedron for two typical types of the ideal perovskite structure distortions. The stability of the obtained probe under the variations of DW-factors is revealed. The application of this probe provides the regular approach to choose the model of radial atomic distribution function used then for precise determination of structure parameters. With its help the Nb displacement in orthorhombic phase of KNbO3 is identified removing the contradiction between X-ray diffraction and EXAFS data.
© EDP Sciences 1997