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The structure of evaporated amorphous Ge$_x$Sb$_x$Te$_{100-2x}$ ($x =$ 6, 9, 13) alloys was investigated by neutron diffraction, X-ray diffraction and extended X-ray absorption spectroscopy (EXAFS) at the Ge, Sb and Te K-edges. Large scale structural models were generated by fitting the experimental datasets (5 for each composition) simultaneously in the framework of the reverse Monte Carlo simulation technique. It was found that the alloys are chemically ordered (Ge and Sb have predominantly Te neighbors) and within the experimental uncertainty each component satisfies the $8-N$ rule. A comparison with the pair correlation functions of melt quenched Ge$_{20}$Te$_{80}$ revealed that the first minimum of $g_{\mathrm{TeTe}}(r)$ is shallower in the ternary alloys than in Ge$_{20}$Te$_{80}$. On the other hand, the separation of the first and second coordination environments of Ge atoms is stronger in the Ge-Sb-Te alloys investigated., Comment: 32 pages, submitted to Journal of Alloys and Compounds

Improvement of electrochemical technologies is one of the most popular topics in the field of renewable energy. However, this process requires a deep understanding of the electrode electrolyte interface behavior under operando conditions. X-ray absorption spectroscopy (XAS) is widely employed to characterize electrode materials, providing element-selective oxidation state and local structure. Several existing cells allow studies as close as possible to realistic operating conditions, but most of them rely on the deposition of the electrodes on conductive and X-ray transparent materials, from where the radiation impinges the sample. In this work, we present a new electrochemical flow-cell for operando XAS that can be used with X-ray opaque substrates, since the signal is effectively detected from the electrode surface, as the radiation passes through a thin layer of electrolyte. The electrolyte can flow over the electrode, reducing bubble formation and avoiding strong reactant concentration gradients. We show that high-quality data can be obtained under operando conditions, thanks to the high efficiency of the cell from the hard X-ray regime down to 4 keV. We report as a case study the operando XAS investigation at the Fe and Ni K-edges on Ni-doped maghemite films, epitaxially grown on Pt substrates. The effect of the Ni content on the catalytic performances for the oxygen evolution reaction is discussed., Comment: 11 pages, 9 figures, available supporting information