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, BaPt⁴⁺_1−2x(Pt ²⁺_1−yBa ²⁺_y )_xO_3−3x with x = 0.25, y ≃ 0 and BaZnFe₆O₁₁, 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.