USE OF ANOMALOUS DIFFRACTION, DAFS AND DANES TECHNIQUES FOR SITE-SELECTIVE SPECTROSCOPY OF COMPLEX OXIDES

The diffraction anomalous fine structure (DAFS) technique is applied t o highly absorbing 'real' crystals of arbitrary shape containing sever al heavy atoms. A multiwavelength refinement procedure of DAFS signals is demonstrated on two different oxides, BaPt1-2x4+(Pt1-y2+Bay2+)(x)O -3-3x with x = 0.25, y similar or equal to 0 and BaZnFe6O11, which hav e complex crystallographic structures. In these compounds, anomalous s catterers are located in different crystallographic sites and thus a m ultiwavelength refinement is necessary to separate out the site-select ive 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.