We have investigated amorphous GeTe by anomalous X‐ray scattering coupled with reverse Monte Carlo modeling. Experiments were conducted at the two K‐absorption edges in order to determine differential structure factors for both elements. The results indicate that simple models like the 8−N bonding rule cannot accurately rationalize the atomic structure. Te atoms are found to be over‐coordinated with a mean coordination number of about 2.5. Moreover, evidence is given for a high level of intermediate‐range order based on Ge, which has not been reported previously. This order has a pronounced effect on the ring statistics observed in the amorphous network, and thereby on the phase‐change speed of GeTe.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have demonstrated a very strong application potential. In order to realize it, the synthesis of stoichiometric 2D TMDCs on a large scale is crucial. Here, we consider a typical TMDC representative, MoS 2 , and present an approach for the fabrication of well-ordered crystalline films via the crystallization of a thin amorphous layer by annealing at 800 °C, which was investigated in terms of long-range and short-range orders. Strong preferential crystal growth of layered MoS 2 along the ⟨002⟩ crystallographic plane from the as-deposited 3D amorphous phase is discussed together with the mechanism of the crystallization process disclosed by molecular dynamic simulations using the Vienna Ab initio Simulation Package. We believe that the obtained results may be generalized for other 2D materials. The proposed approach demonstrates a simple and efficient way to fabricate thin 2D TMDCs for applications in nanoand optoelectronic devices.

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The first direct valence‐selective structure determination by X‐ray fluorescence holography is reported. The method is applied to investigate an epitaxial thin film of the rare earth monoxide YO, which has recently been synthesized by pulsed laser deposition. The surface of the sample is easily oxidized to Y2O3. In order to separate the structural information connected with the two different valence states of Y, the X‐ray fluorescence holography measurements were performed close to the Y K absorption edge. Using the shift of the absorption edge for the different valence states, very different relative contributions of YO and Y2O3 are obtained. Thus, it is possible to distinguish the crystal structures of YO and Y2O3 in the thin‐film sample.