The lithium‐conducting, rare‐earth halides, Li₃MX₆ (M = Y, Er; X = Cl, Br), have garnered significantly rising interest recently, as they have been reported to have oxidative stability and high ionic conductivities. However, while a multitude of materials exhibit a superionic conductivity close to 1 mS cm⁻¹, the exact design strategies to further improve the ionic transport properties have not been established yet. Here, the influence of the employed synthesis method of mechanochemical milling, compared to subsequent crystallization routines as well as classic solid‐state syntheses on the structure and resulting transport behavior of Li₃ErCl₆ and Li₃YCl₆ are explored. Using a combination of X‐ray diffraction, pair distribution function analysis, density functional theory, and impedance spectroscopy, insights into the average and local structural features that influence the underlying transport are provided. The existence of a cation defect within the structure in which Er/Y are disordered to a new position strongly benefits the transport properties. A synthetically tuned, increasing degree of this disordering leads to a decreasing activation energy and increasing ionic conductivity. This work sheds light on the possible synthesis strategies and helps to systematically understand and further improve the properties of this class of materials.

Over the last decade, some studies with laboratory pair distribution function (PDF) data emerged. Yet, limited Q_max or instrumental resolution impeded in-depth structural refinements. With more advanced detector technologies, the question arose how to design novel PDF equipment for laboratories that will allow decent PDF refinements over r = 1–70 Å. It is crucial to reflect the essential requirements, namely, monochromatic X-rays, suppression of air scattering, instrumental resolution, and overall measurement times. The result is a novel PDF setup based on a STOE STADI P powder diffractometer in transmission-/Debye-Scherrer geometry with monochromatic Ag Kα₁ radiation, featuring a MYTHEN2 4K detector covering a Q range of 0.3–20.5 Å⁻¹. PDF data are collected in a moving PDF mode within 6 h. Structural signatures of liquids can be satisfactorily resolved in the PDF as shown for the ionic liquid hmimPF₆. The high instrumental resolution is mirrored in low q_damp values determined from LaB₆ measurements. PDF data from a powder sample of ca. 7 nm TiO₂ nanoparticles were successfully refined over up to 70 Å with goodness-of-fit values R_w < 0.22 (respectively R_w = 0.18 over 30 Å), thanks to the low background and high instrumental resolution, hereby enlarging the accessible r range by several tens of Angstroms compared to previous laboratory PDF studies.

Thermal decomposition of metal–organic framework (MOF) precursors is a recent method to create well-dispersed metal centers within active catalyst materials with enhanced stability, as required for dynamic operation conditions in light of challenges caused by the renewable energy supply. Here, we use a hard X-ray-based toolbox of pair distribution function (PDF) and X-ray absorption spectroscopy (XAS) analysis combined with X-ray diffraction and catalytic activity tests to investigate structure–activity correlations of methanation catalysts obtained by thermal decomposition of a Ni(BDC)(PNO) MOF precursor. Increasing the decomposition temperature from 350 to 500 °C resulted in Ni_fcc nanoparticles with increasing particle sizes, alongside a decrease in Ni²⁺ species and strain-induced peak broadening. For lower temperatures and inert atmosphere, Ni₃C and NiO phases co-existed. A graphitic shell stabilized the Ni particles. Compared to an inert atmosphere, reducing conditions led to larger particles and a faster decomposition of the MOF precursor. Catalytic studies revealed that the decomposition at an intermediate temperature of 375 °C in 5% H₂/He is the best set of parameters to obtain high specific surface areas while maintaining particle sizes that feature many active Ni centers for the formation of CH₄.

The synthesis of Mg‐substituted copper hydroxycarbonates by constant‐pH co‐precipitation with subsequent ageing of the precipitate has been studied in detail. This allowed the retrieval of crystalline magnesian malachite samples, which showed a “radical‐sign‐shaped” pH drop and the blue/green color change during ageing that is well‐known from the analogous Cu/Zn system. The crystallization of Cu‐rich samples has been studied elaborately by means of powder diffraction, pair distribution function (PDF), and infrared spectroscopy, thus elucidating the ageing chemistry of Cu,Mg hydroxycarbonates in general. It was found that up to 17 % Mg can be incorporated into the crystalline malachite using a synthesis route comparable to that established for Cu/ZnO catalysts, but with drastically elongated precipitate ageing times. For higher Mg contents, a step‐like pH drop was observed instead, and an amorphous variant of the hydroxycarbonate, referred to as “magnesian georgeite”, could be isolated. From such a Mg‐rich sample (Cu/Mg 70 : 30 at. %), a Cu/MgO catalyst has been prepared that shows high activity and good stability in CO hydrogenation to methanol over 800 hrs. time on stream.

The replacement of noble metal catalysts by abundant iron as an active compound in CO oxidation is of ecologic and economic interest. However, improvement of their catalytic performance to the same level as state-of-the-art noble metal catalysts requires an in depth understanding of their working principle on an atomic level. As a contribution to this aim, a series of iron oxide catalysts with varying Fe loadings from 1 to 20 wt% immobilized on a γ-Al₂O₃ support is presented here, and a multidimensional structure–activity correlation is established. The CO oxidation activity is correlated to structural details obtained by various spectroscopic, diffraction, and microscopic methods, such as PXRD, PDF analysis, DRUVS, Mössbauer spectroscopy, STEM-EDX, and XAS. Low Fe loadings lead to less agglomerated but high percentual amounts of isolated, tetrahedrally coordinated iron oxide species, while the absolute amount of isolated species reaches its maximum at high Fe loadings. Consequently, the highest CO oxidation activity in terms of turnover frequencies can be correlated to small, finely dispersed iron oxide species with a large amount of tetrahedrally oxygen coordinated iron sites, while the overall amount of isolated iron oxide species correlates with a lower light-off temperature.