Use of Anomalous Diffraction, DAFS and DANES Techniques for Site-Selective Spectroscopy of Complex Oxides.

The diffraction anomalous fine structure (DAFS) technique is applied to highly absorbing ;real' crystals of arbitrary shape containing several heavy atoms. A multiwavelength refinement procedure of DAFS signals is demonstrated on two different oxides, BaPt(4+)(1-2x)(Pt( 2+)(1-y)Ba( 2+)(y) )(x)O(3-3x) with x = 0.25, y approximately 0 and BaZnFe(6)O(11), which have complex crystallographic structures. In these compounds, anomalous scatterers are located in different crystallographic sites and thus a multiwavelength refinement is necessary to separate out the site-selective information. An accurate absorption correction procedure for small, highly absorbing single crystals necessary for the DAFS analysis of this kind of samples is also presented.