Intermetallic phases are known to significantly influence the evolution of the local microstructure in Al alloys during processing and thus affect their mechanical properties. However, non-destructively mapping the local orientation and strain fields around intermetallic particles remains technically challenging. Here, we present a multi-modal synchrotron X-ray study on an Al2050 alloy to map the orientations and strains in both Al grains and secondary-phase particles as a function of tensile loading in the elastic regime. Combined with phase contrast tomography (PCT), we visualize the spatial distribution of the secondary phases and pre-existing pores together with the 3D Al grain structure characterized by diffraction contrast tomography (DCT), while higher resolution mappings of orientations and strains for both Al and secondary phase particles (Al7Cu2Fe) are resolved by scanning 3D X-ray diffraction (s3DXRD). This multi-modal approach not only allows comprehensive microstructure characterization, but also cross-validates the grain orientation reconstruction. The results show that during tensile loading, the intermetallic particles undergo a compressive strain and induce a high stress gradient and unexpected lattice rotation in a local area of an Al grain. This highlights the presence of grain plasticity at only 55% of the yield stress influenced by the intermetallic particles. We demonstrate that studying the evolution of the matrix-precipitates microstructure greatly benefits from the multi-modal approach of combining PCT, DCT and s3DXRD.

Boron carbide is a material of choice for multiple industries, e.g., aerospace, as a lightweight structural ceramic due to its high hardness, high melting temperature, and low density. However, its mechanical properties have been observed to radically degrade under shockwave compression, presumably as a consequence of stress-induced phase transitions resulting in its partial amorphization. So far, the physical mechanism underpinning this behavior remains unclear. Here, we report a pressure-induced phase transition in boron carbide occurring between 78 and 90 GPa during static compression in diamond anvil cells, both at room temperature and after quenching from high temperatures. The crystal structure of the new phase was solved and refined via synchrotron single-crystal x-ray diffraction measurements and further investigated by Raman spectroscopy as well as density functional theory calculations. The discovered high-pressure polymorph, mC60-B13C2, has strong resemblance with the known ambient conditions phase, hR45-B13C2, with the important distinction that the linear C-B-C chain linking B12 icosahedra in hR45-B13C2 is bent in mC60-B13C2. Such bending of the C-B-C chain has been hypothesized as key to explain boron carbide's drop in strength, phase transitions, and amorphization. The observed reversibility of the phase transition, as well as the formation of covalent bonds between B12 icosahedra and the bent C-B-C chains, are assessed to decipher the C-B-C chain's bending importance on the amorphization and mechanical properties of boron carbide.

We discover a rare structural manifestation of the Goldstone paradigm in a hexagonal polytype of the prototypical ferroelectric BaTiO_{3}. First-principles calculations confirm the Goldstone character of the order parameter, while our high-resolution diffraction measurements unveil an unusual reentrant Goldstone regime manifesting as a quasicontinuous domain texture in the vicinity of the ferroelectric transition. We develop a minimal Landau model that encapsulates these observations, illustrating how U(1) symmetry can be restored at the ferroelectric transition. Our findings demonstrate how exotic Goldstone physics can be unlocked in systems dominated by highly anharmonic interactions, presenting a promising pathway to stabilize emergent polar topologies in bulk materials.

Battery research increasingly relies on advanced imaging, yet open access to such data remains rare, scattered across various sources, and difficult to find. The Battery Imaging Library (BIL) is the...

Metallization layers play a key role in the performance and reliability of modern power semiconductor devices. During short-circuit events, rapid heating of power metallization layers induces thermomechanical incompatibility stresses, which may contribute to material degradation and impact device performance. In this work, potential degradation hotspots associated with thermomechanical loading in Cu power metallization are investigated using a combined experimental–computational approach. Scanning three-dimensional X-ray diffraction measurements are coupled with thermomechanical crystal plasticity simulations to probe the evolution of grain-resolved plastic deformation during rapid cyclic loading. This integrated approach provides insight into the microstructural processes governing degradation hotspot formation, laying the groundwork for future microstructure-informed, physics-based reliability assessment of Cu metallization.

High-pressure synthesis provides unique pathways to materials with unprecedented structures and properties. Here we report the synthesis and structural characterization of novel rare-earth (La, Sm, Gd, Dy) chlorides, chloride carbides, and oxychloride phases obtained due to complex chemical reactions in diamond anvil cells after laser heating of rare-earth metals and NaCl at pressures of 39-127 GPa and temperatures of 2500-2800 K. Synchrotron single-crystal X-ray diffraction analysis allowed us to solve previously unknown crystal structures of binary (La2Cl, LaCl, LaCl3, DyCl) and ternary (DyNa2Cl5, Sm2ClC2, Gd2ClC2, Dy2ClC2, Sm19ClC18, Gd19ClC18, Dy5Cl3C, DyOCl) compounds. Significantly, we identified trans-polyacetylene-like carbon chains in lanthanide chloride carbides, a structural motif previously hypothesized but not observed experimentally. Our findings highlight the enhanced chemical reactivity of alkali halides under extreme conditions, uncovering novel chemical bonding and expanding the landscape of potential functional materials accessible through high-pressure synthesis.

Being a noble metal, silver is known for its chemical inertness. Molecular nitrogen, due to its extremely strong covalent triple bond, is also typically considered unreactive. It is thus unsurprising that no credible report on the formation of a thermodynamically stable silver and nitrogen compound exists. In this study, we report the synthesis of silver pentazolate (AgN5), achieved through the direct reaction of elemental silver with molecular nitrogen at a pressure of 118(3) GPa and a temperature of 2000(200) K. The crystal structure of AgN5 was determined from synchrotron single-crystal X-ray diffraction (SCXRD) data, revealing it to be comprised of cyclo-N5 - anions. Remarkably, this solid's structure does not correspond to any of the silver nitrides previously predicted. Moreover, density functional theory (DFT)-based enthalpy convex hull calculations demonstrate that this AgN5 compound is the only thermodynamically stable Ag-N solid between 10 and 120 GPa while also providing information on its phonon and electron band structures, including its electronic band gap. Both DFT calculations and SCXRD experimental data yield insights into the stability pressure range of AgN5 upon decompression. This study provides yet another example of the capability of high pressure and high temperature to facilitate unprecedented chemical reactions between elements often assumed to be inert, in turn enabling the formation of novel nitrogen-rich compounds.

Understanding the mechanisms controlling brittle rock failure at the grain to sub-grain scale is a fundamental challenge in geosciences. Recent advances in triaxial compression and dynamic shock experiments combined with dynamic X-ray microtomography provide unparalleled insights into the 3D strain field evolution within deforming rocks. However, these methods do not accurately predict the heterogeneous internal stress field prior to failure, which is crucial for predicting microfracture initiation and propagation, leading to macroscopic failure. In the past decade, efforts have focused on developing synchrotron X-ray diffraction techniques leveraging the high penetrative capacity of hard X-rays from the last generations of synchrotron light sources. These techniques offer spatially resolved information on crystal phase orientation and elastic strain within a 3D volume. The local orientation and elastic strain tensor is reconstructed grain-by-grain, with precision down to approximately 10-3 radian for orientation and 10-4 for strain. Stress is then calculated using Hooke's law for anisotropic materials and the elastic constants of the crystal phases. We employed 3D X-ray diffraction to investigate the internal stress field evolution in a rock core sample deformed under triaxial compression in the Hades apparatus. A 5mm-diameter core of Berea sandstone was subjected to axial step loading under constant radial stress of 10 MPa, reaching brittle failure at around 90 MPa differential stress. Elastic strain of individual quartz grains were measured at different load steps, and elastic stresses were calculated, providing maps of the internal strain and stress field in the sample. Results reveal progressive elastic shortening of quartz grains parallel to the compression axis and elongation in orthogonal directions due to the Poisson’s effect. Reorientation of principal stress components is also observed with increasing axial stress, which tend to align with the macroscopic stress field. Internal stresses distribution varies within a range of ca. 300 MPa, suggesting local stress amplifications occurred interpreted as force chains, potentially favoring crack nucleation. This experiment is among the first ones to characterize in-situ the stress distribution in a natural rock under compressive loading, and demonstrates the potential of synchrotron diffraction techniques for investigating strain and stress in geological materials.

All ferromagnetic Fe-based bulk metallic glasses show the Invar effect. It is a magnetic effect that reduces the coefficient of thermal expansion and comes in two forms, a step-type and a peak-type effect. Here, we study the atomic arrangement of an (Fe71.2B24Y4.8)96Nb4 bulk metallic glass as a function of temperature and across more than six orders of magnitude in length scale. Combining various synchrotron-based X-ray scattering techniques we show that the Invar effect originates at the atomic scale within the Fe-Fe network. We find no signs of increased spatial correlations due to the ferromagnetic interactions. This shows that no structural rearrangement occurs at the Curie temperature and that the Invar effect is purely of energetic nature. We conclude that the Invar effect has a fundamental base that results from the magnetic interactions of Fe-Fe bonds. Based on this, we provide a model for the magnetic interactions that create the Invar effect in amorphous materials.

Gas hydrates are considered fundamental building blocks of giant icy planets like Neptune and similar exoplanets. The existence of these materials in the interiors of giant icy planets, which are subject to high pressures and temperatures, depends on their stability relative to their constituent components. In this study, we reexamine the structural stability and hydrogen content of hydrogen hydrates, (H2O)(H2)n, up to 104 GPa, focusing on hydrogen-rich materials. Using synchrotron single-crystal X-ray diffraction, Raman spectroscopy, and first-principles theoretical calculations, we find that the C2-filled ice phase undergoes a transformation to C3-filled ice phase over a broad pressure range of 47 - 104 GPa at room temperature. The C3 phase contains twice as much molecular H2 as the C2 phase. Heating the C2-filled ice above approximately 1500 K induces the transition to the C3 phase at pressures as low as 47 GPa. Upon decompression, this phase remains metastable down to 40 GPa. These findings establish new stability limits for hydrates, with implications for hydrogen storage and the interiors of planetary bodies.

Despite their electronic dominance, cubic diamond structured Si and Ge, are optoelectronically deficient. Recent work indicates, however, that a volume-expanded hexagonal Ge modification can exhibit intensely sought, superior optoelectronic characteristics. If larger Sn could form a hexagonal solid solution with Ge, this would achieve this expansion. But this was not expected because Ge and Sn are unreactive at ambient conditions, Sn does not have an ambient hexagonal symmetry, and only cubic or tetragonal binary modifications could be prepared under any conditions including thin film processing. This state of affairs is categorically changed here by subjecting Ge and Sn to pressures of 9 and 10 GPa and temperatures up to 1500 K using large-volume press methods. Synchrotron angle-dispersive X-ray diffraction, precession electron diffraction and chemical analysis using electron microscopy reveal ambient pressure recovery of hexagonal 2H, 4H and 6H Ge-Sn solid solutions (P63/mmc). Formation of this new binary materials landscape is correlated with Sn uptake, with the hexagonal symmetry being accessible below 21 atom % Sn and the cubic diamond symmetry at or above this value. The findings form fertile routes to advanced materials, by in tandem creating reactivity with pressure and directing production of needed crystal symmetries with composition, as well as opportunity to tune properties based on crystal symmetry, composition, and stacking sequence for optoelectronic applications.

The microscopic distribution of strain and stress plays a crucial role for the performance, safety, and lifetime of components in aeronautics, automotive and critical infrastructure [1]. While non-destructive methods for measuring the stress close to the surface have long been long established, only a limited number of approaches for depth-resolved measurements based on x-rays or neutrons are available [2]. These feature significant limitations, including long scan times, intricate experimental set-ups, limited spatial resolution or anisotropic gauge volumes with aspect ratios of 1:10 or worse. Here, we present a method that overcomes these limitations and obtains tomographic reconstructions of the full six-dimensional strain and stress tensor components. Using a simple and wide spread experimental set-up that combines x-ray powder diffraction with single axis tomography, we achieve non-destructive determination of depth-resolved strain and stress distributions with isotropic resolution. The presented method could be of interest for additive manufacturing of metals [3,4], battery research [5], in-situ metallurgy [6] and the experimental validation of finite element simulations [7].

Measuring and understanding brittle failure at the (sub)‐grain scale is a key challenge to unravel the initiation of system‐size failure in rocks. Recent developments in synchrotron X‐ray diffraction techniques enable non‐destructive in situ measurements of crystal lattice orientation, elastic strain, and stress at grain to intra‐grain scales. We used scanning three‐dimensional X‐ray diffraction to study the stress evolution in Berea and Fontainebleau sandstone cores deformed under triaxial compression. Experiments were conducted at the European Synchrotron Radiation Facility using the Hades apparatus, which allows simultaneous triaxial compression testing and X‐ray data acquisition. Stepwise axial loading was applied to the samples while maintaining a constant 10 MPa confinement. Diffraction scans in quartz provided time‐series stress maps across a core transect with a 50 µm resolution. Results reveal progressive internal stress buildup consistent with macroscopic loading, accompanied by reorientation of local stress tensors that increasingly align with the bulk macroscopic stress. Significant stress heterogeneity is observed, reflecting non‐uniform load distribution across the sample and the presence of initial residual stress. This heterogeneity grows with increasing loading and forms spatially persistent patterns that resemble force‐chain networks in granular materials. The increasing heterogeneity and spatial persistence of the stress field may control the development of tensile microfractures, ultimately leading to macroscopic failure. Used in combination with dynamic X‐ray microtomography that captures the three‐dimensional strain field evolution, scanning three‐dimensional X‐ray diffraction emerges as a powerful tool for quantifying heterogeneous internal stress and provides additional constraints on stress at the onset of microfracture initiation and propagation.

We applied synchrotron x-ray diffraction in a diamond-anvil cell at 48-51 GPa, alongside first-principles theoretical calculations, to study the crystal structure of solid atomic iodine at high pressure. We report the synthesis of two phases of atomic iodine at 48-51 GPa via laser heating of iodine (I) in nitrogen (N2) or neon (Ne) media. Unlike the familiar monatomic I4/mmm structure, which consists of crystallographically equivalent atoms, a previously unobserved Pm3n structure determined by single-crystal and powder x-ray diffraction is of an inclusion type, featuring two distinct types of atoms: a central, detached atom and peripheral atoms that form linear chains. Additionally, we observe crystallization of the familiar high-pressure fcc structure, albeit at much lower pressures compared to cold-compressed iodine. The discovery of the Pm3n structure in iodine marks an important step in understanding the pressure-induced phase transition sequence in halogens.

Metallic glasses and their resulting nanocrystalline composites reveal very favorable properties that have been recognized from the early stage of their development. Of vital importance is the structure at the nanoscale and the possibility of tailoring it. Controlled nanocrystallization is one prerequisite for metallic glass functionalization, but this method cannot be extensively applied without a priori knowledge of the phase formation. Moreover, in the case of well-established characterization methods only a very small amount of material is generally analyzed, where it is questionable whether the bulk material properties are addressed. In this study we apply in situ synchrotron X-ray diffraction to achieve accurate details on the structural relaxation and evolution of an (Fe, Co)-based bulk Finemet-type alloy. Via comprehensive analysis of both the reciprocal- and direct-space data, we show that the Fe35.8Co35.8B19.1Si4.8Nb4.0Cu0.5 BMG rods with 2 mm diameter reveal just minimal structural relaxation prior to the glass transition (Tg). In turn, immediately above Tg, alpha-Fe-like nanocrystals start to form and undergo a continuous change in their chemical composition. Upon temperature increase, the first atomic shell does not expand as long as the alloy is still in the amorphous state, but shrinks as nanocrystallization proceeds.

The hydrous borocarbonate B[μ-H(CO3)2] was synthesized in a laser-heated diamond anvil cell at moderate pressures (∼20 GPa) and temperatures (∼1500(200) K) by a reaction between B2O3, CO2 and H2O. The crystal structure was obtained from synchrotron single-crystal X-ray diffraction and confirmed by a combination of density functional theory (DFT) calculations and Raman spectroscopy. Second harmonic generation (SHG) measurements corroborated the acentric space group, while DFT calculations provided the complete SHG tensor. In the [μ-H(CO3)2]3- building block two [CO3]2- groups are connected by sharing a hydrogen atom, which is bound in a nearly linear and symmetric O-H-O arrangement. B[μ-H(CO3)2] is a hydrous borocarbonate without further cations, combining interesting chemical and physical properties such as symmetric hydrogen bonds and a significant SHG intensity.

The authors report a combination of multimodal scanning three-dimensional X-ray diffraction (S3DXRD), X-ray diffraction computed tomography (XRD-CT), and X-ray fluorescence computed tomography (XRF-CT) used for the first time to provide multiscale (spanning the size regime 0.15-500 mu m) insight into the aging of a CeO2-ZrO2 solid solution known to exhibit outstanding reversible oxygen storage capacity (OSC). The authors show that using nanobeams is necessary to map in detail the distribution of elements and crystalline phases. In particular, the latter information is derived from two imaging methodologies to capture the diffraction signal originating from single crystals and powder-averaged crystallites, respectively. Ultimately, a decrease in relative OSC by 25% in the aged material could be correlated with a transformation of the cation-ordered pyrochlore Ce2Zr2O7 phase to the cation-disordered CeO2-ZrO2 fluorite structure. This is manifested as a loss in homogeneity of Ce and Zr distribution of the cation-ordered pyrochlore seen by nanoXRF-CT. The diffraction signal in both the S3DXRD and XRD-CT provides evidence that the solid-state transformation between the phases preferentially takes place at the periphery of the catalyst particle, resulting in a pyrochlore-rich core and fluorite on the surface and accompanied by significant sintering.

The anhydrous beryllium carbonate Be[CO3] with calcite-type crystal structure was obtained by a reaction of BeO with CO2 in a laser-heated diamond anvil cell at pressures between 30 GPa and 80 GPa and elevated temperatures. Its calcite-type crystal structure (R3c with Z = 6) is characterized by 6-fold-coordinated beryllium atoms forming [BeO6] octahedra and by trigonal-planar [CO3](2-) groups. The crystal structure was determined by synchrotron-based single-crystal X-ray diffraction and confirmed by density-functional-theory-based calculations in combination with experimental Raman spectroscopy. Calcite-type Be[CO3] was synthesized at significantly lower pressures than the other very few compounds hosting 6-fold-coordinated beryllium, and it is the first beryllium carbonate with this coordination.