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The amorphous structure of (Ga2Se3)0.25(GeSe2)0.75 is investigated using a combination of anomalous X-ray scattering (AXS) and Reverse-Monte-Carlo (RMC) modeling. It was confirmed that the Ga and Ge atoms can be found exclusively in the tetrahedral configuration. The average coordination number of the Se atoms is found to be 2.34(3) due to the presence of dative bonds. The formation of Ga/Ge-Ga/Ge so-called "wrong bonds" is discussed based on a set of RMC simulations. A strong Ga-Ga second neighbor correlations indicates the formation of Ga-Se clusters within the Ga-Ge-Se glass. [ABSTRACT FROM AUTHOR]

We have investigated the local atomic structures of several compositions of the amorphous phase of the system Cu x Ge50-xTe 50 (0⩽x⩽33.3), based on extended x-ray absorption fine-structure as well as anomalous x-ray scattering experiments, and discuss the unusual trend regarding their thermal stability as a function of the Cu content. At low concentrations (x⩽15), Cu atoms tend to agglomerate in flat nanoclusters reminiscent of the crystalline phase of metallic Cu, leading to a more and more Ge-deficient Ge-Te host network structure with growing Cu content and an increasing thermal stability. At higher Cu concentrations (x⩾25), Cu is incorporated into the network, leading to an overall weaker bonding situation which is associated with a decreasing thermal stability., (© 2023 IOP Publishing Ltd.)