Construction of the model radial distribution curves with regard to the features of X-ray diffraction experiment

Structure of Copper Oxide Species Supported on Monoclinic Zirconia

“…Structural features of supported copper species were determined by analyzing the Fourier transformation of normalized X-ray diffraction scattering, which yields the radial distribution function of electron density 4πr 2 ρ­(r) − or the pair distribution function 4πr­[ρ­( r ) – ρ 0 ] (where ρ­( r ) is the electron density at distance r and ρ 0 is the average electron density corresponding to a random atom distribution). The used calculation technique is described elsewhere. ,, The procedure allows interatomic distances ( r ) and coordination numbers (CN) to be determined from position and area of peaks in the RDF curve. The analysis of RDF provides information about the local atomic structure and makes it possible to identify phases with a CSD size smaller than 3 nm.…”

“…The analysis of RDF provides information about the local atomic structure and makes it possible to identify phases with a CSD size smaller than 3 nm. A comparison between the experimental and model RDFs is usually performed. , The data required for modeling RDF, such as interatomic distances and coordination numbers, were calculated from structural data available in the ICSD database . The XRD patterns required for the RDF calculations were obtained using a high-resolution diffractometer at the Siberian Synchrotron and Terahertz Radiation Centre (SSTRC, Budker Institute of Nuclear Physics, Novosibirsk, Russia).…”

Effect of structural defects in alumina supports on the formation and catalytic properties of the active component of reforming catalysts

“…Data collection covered a in the 2h angle range of 5-135°. PDF curves of the samples were calculated by a technique reported by Moroz et al [5,19,20] and then compared with the model curves for c-Al 2 O 3 presented in [6,19]. Considering the possible formation of oxide phases upon exposure of the catalysts to air, we plotted model curves for H 2 Pt(OH) 6 crystal phases and various platinum oxides using structural data from the ICSD/Retrieve database [21].…”

“…A previous PDF study [20] revealed the presence of isolated sections on the surface of the spinel-like alumina phase where octahedral vacancies are occupied by platinum ions, which are the formation sites for disperse zero valent platinum. It has been demonstrated [8,9] that due to a strong interaction with the support, the platinum is present as complexes of platinum(II) built into the surface layers of the alumina at the sites of its structural defects.…”

“…In this context, it becomes necessary to compare experimental PDF curves with the model curves plotted for an expected phase composition [19,20]. This may not only refine the phase composition (for X-ray amorphous and finely dispersed materials) but may also reveal structural features of the phases present in the material.…”