《A Comparison between XRD-Rietveld and EXAFS Results》.pdf

Journal of Solid State Chemistry 167, 126–136 (2002) doi:10.1006/jssc.2002.9634 Structural Investigations of ACu Ru O (A=Na, Ca, Sr, La, Nd)FA 3 4 12 Comparison between XRD-Rietveld and EXAFS Results S. G. Ebbinghaus,n,1 A. Weidenkaff,n and R. J. Cavaw nInstitut fur Physik, Universitat Augsburg, Universitatsstraße 1, D-86159 Augsburg, Germany; an wDepartment of Chemistry, . . . Princeton University, Princeton, New Jersey 8544 symmetry Sr2RuO4 analogue only by a slight rotation of The structures of five perovskite-related oxides with the the IrO6-octahedra (2, 3). general composition ACu3Ru O12 with A =Na, Ca, Sr, La and While a precise determination of oxygen positions can be Nd, have been examined both by XRD-Rietveld refinements and achieved by using neutrons instead of X rays, a more Ru-K EXAFS-spectroscopy. In addition, the behavior on serious problem remains: All diffraction methods rely on reduction was investigated by thermogravimetry (TG). The TG well-crystallized samples with a sufficiently large grain size. measurements revealed that the composition was almost exactly In recent years, new preparation techniques like co- A Cu Ru O for all samples. The inter-atomic distances 1 3 12 precipitation, sol–gel synthesis or microemulsion methods