Determination of the distribution of elements with similar electron counts: a practical guide for resonant X-ray scattering

Abstract

This article attempts to present straightforward and easy-to-understand guidelines for the determination of element distribution in compounds lacking X-ray scattering contrast because they have similar electron counts. Different sources of anomalous dispersion correction terms (especially Áf 0 values) are compared with respect to their suitability, reliability and quality. Values from databases are compared with Áf values calculated from fluorescence spectra and those refined from single-crystal diffraction data, using both reference crystals without scattering contrast problems and crystals containing elements with similar electron counts. The number of data sets required to determine reliably the element distribution and the optimum wavelengths to be used are discussed. Joint multiple data set refinements are suitable for the refinement of multiply mixed occupancies of elements lacking scattering contrast. The most straightforward method of obtaining Áf 0 values depends on the complexity of the problem to be solved and the precision required.

Nondestructive Method for the Determination of the Electric Polarization Orientation in Thin Films: Illustration on Gallium Ferrite Thin Films

“…This approach, which can be identified as diffraction anomalous fine structure or diffraction anomalous near‐edge structure (DANES), combines diffraction with X‐ray absorption fine structure or X‐ray absorption near edge structure methods. It is both sensitive to the local environment of the absorbing atom though the anomalous process and to the long range order involved in the diffraction process and has been widely used to investigate the local environment of the cations in oxides and locating metal atoms on different sites, even in cases of small occupancies, and even in mixed metal situations . In a previous study, we have demonstrated the possibility to unambiguously determine the cationic distribution in oxide thin films from the simultaneous fit of a set of resonant diffraction spectra using a dedicated Python code.…”

“…It is both sensitive to the local environment of the absorbing atom though the anomalous process and to the long range order involved in the diffraction process and has been widely used to investigate the local environment of the cations in oxides [22][23][24][25][26][27][28][29] and locating metal atoms on different sites, even in cases of small occupancies, and even in mixed metal situations. [30][31][32][33] In a previous study, [34] we have demonstrated the possibility to unambiguously determine the cationic distribution in oxide thin films from the simultaneous fit of a set of resonant diffraction spectra using a dedicated Python code. Here, we show that this approach can be used to determine the polarization state in multiferroic GFO thin films of various orientations.…”

The Influence of Nanoscale Heterostructures on the Thermoelectric Properties of Bi-substituted Tl5Te3

“…Therefore, the experimental determination of site occupancies has to be carried out by resonant X‐ray scattering. By utilizing anomalous dispersion at the absorption edges of each element, one can distinguish elements with similar electron counts , …”

“…By utilizing anomalous dispersion at the absorption edges of each element, one can distinguish elements with similar electron counts. [15,16] Figure 1. Crystal structures of (a) Tl 4.5 Bi 0.5 Te 3 [12] and (b) TlInTe 2 [26] with characteristic coordination polyhedra (gray; a: centered by Bi/Tl, b: centered by In) and predominant bonds (dark red).…”

Solid Solution Series between CdIn2Te4 and AgInTe2 Investigated by Resonant X‐ray Scattering

“…It is crucial to find a suitable source for ΔfЈ and to perform joint refinements on datasets at various wavelengths in order to determine the element distribution. [9] Recently, resonant X-ray scattering was successfully applied to determine the element distribution in single crystals of a broad range of comparable chalcogenide systems like Ge/Sn/Sb/Te, [10,11] Ge 3 SbInTe 6 , [12] or SnSb 2 Te 4 . [13] In such layered compounds, for example, the [14] were also investigated concerning their element distribution.…”