The present work shows an approach to monitor the evolution of the dislocation arrangement of a metallic material caused by cyclic plastic strain using white X-ray radiation in combination with an energy-dispersive detector. The method is demonstrated by single-shot experiments performed on polycrystalline nickel and alpha-brass, representing the pure wavy and the pure planar dislocation slip behavior. To correlate the resulting diffraction patterns with various dislocation arrangements of both metals, fatigue tests were carried out up to certain numbers of cycles and at predetermined plastic strain amplitudes. The differences in dislocation microstructure and internal stress distributions give rise to an appreciable change in the peak shape of Laue reflections, leading to unique characteristics in the respective diffraction patterns. Nickel reflections are elongated due to the high amount of cell structures leading to bending and misorientation of the lattice, whereas the present stacking faults in alpha-brass result in powder-like diffraction.

The topic of data storage, traceability, and data use and reuse in the years following experiments is becoming an important topic in Europe and across the world. Many scientific communities are striving to create open data by the FAIR principles. This is a requirement from the European Commission for EU-funded projects and experiments at EU-funded research infrastructures (RIs) and from many national funding agencies. This is challenging for users of large-scale RIs such as neutron, photon, synchrotron and free-electron laser facilities. Users of photon and neutron (PaN) RIs employ a wide range of scattering, imaging and spectroscopic methods investigating the behaviour of matter with a broad scientific base across physics, chemistry and biology, including engineering, environmental, cultural heritage and medical applications. They produce large data volumes of up to 1 PByte per day in some cases. To ensure all these data are FAIR requires an enormous effort from PaN RIs. It requires not only the expansion of data storage capacity, but also the development and deployment of software for effective data storage, metadata schemes and implementation of effective data pipelines at each individual experiment across RIs. FAIR data also affect the carbon footprint related to large amounts of data and raise questions related to user authentication, rights of access and cyber security. The RIs alone cannot achieve such a transformational process. For successful open science, cooperation of the user communities is essential as they need to create and utilize existing tools to deliver FAIR data. In this white paper, the European PaN community outline and discuss the role and responsibilities of the users and RIs and their common accountability to achieve FAIR data. This paper shall serve as a starting point for a common user and RI approach on the European scale to achieve FAIR data.

We report on the fabrication of a novel design of GaAs/(In,Ga)As/GaAs radial nanowire heterostructures on a Si 111 substrate, where, for the first time, the growth of inhomogeneous shells on a lattice mismatched core results in straight nanowires instead of bent. Nanowire bending caused by axial tensile strain induced by the (In,Ga)As shell on the GaAs core is reversed by axial compressive strain caused by the GaAs outer shell on the (In,Ga)As shell. Progressive nanowire bending and reverse bending in addition to the axial strain evolution during the two processes are accessed byin situby x-ray diffraction. The diameter of the core, thicknesses of the shells, as well as the indium concentration and distribution within the (In,Ga)As quantum well are revealed by 2D energy dispersive x-ray spectroscopy using a transmission electron microscope. Shell(s) growth on one side of the core without substrate rotation results in planar-like radial heterostructures in the form of free standing straight nanowires.

Polyvinyl alcohol (PVA) composite thin films were prepared using graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) as carbon fillers (CFs). The resulting electrical, optical, mechanical, and structural changes caused by adding the CFs to the pure PVA matrix were characterized. The improvement of electrical, optical, and mechanical properties was interpreted in terms of the percolation theory. Depending on this interpretation, the percolation threshold values, and the critical exponential values of the related properties were calculated. It turns out that the measured mechanical and optical changes were compatible with the site percolation theory while the electrical conductivity was compatible with the classical percolation theory. X-ray diffraction (XRD) measurements were performed to correlate the physical properties with the structure of the PVA composite films. They revealed that the degree of crystallinity of the composites increased with the CF reinforcement and that MWCNT was more effective in improvement of the crystallinity of the PVA composites than GNP.

We showcase the application of a 2-dimensional detector for observing energy and momentum-correlated x-ray pairs. This detector introduces novel possibilities for applications in quantum x-ray optics.

We address the identification of grain-corresponding Laue reflections in energy dispersive Laue diffraction (EDLD) experiments by formulating it as a clustering problem solvable through unsupervised machine learning (ML). To achieve reliable and efficient identification of grains in a Laue pattern, we employ a combination of clustering algorithms, namely hierarchical clustering (HC) and K-means. These algorithms allow us to group together similar Laue reflections, revealing the underlying grain structure in the diffraction pattern. Additionally, we utilise the elbow method to determine the optimal number of clusters, ensuring accurate results. To evaluate the performance of our proposed method, we conducted experiments using both simulated and experimental datasets obtained from nickel wires. The simulated datasets were generated to mimic the characteristics of real-world EDLD experiments, while the experimental datasets were obtained from actual measurements.

Here we report on the non-uniform shell growth of InxGa1-xAs on the GaAs nanowire (NW) core by molecular beam epitaxy (MBE). The growth was realized on pre-patterned silicon substrates with the pitch size (p) ranging from 0.1 μm to 10 μm. Considering the preferable bending direction with respect to the MBE cells as well as the layout of the substrate pattern, we were able to modify the strain distribution along the NW growth axis and the subsequent bending profile. For NW arrays with a high number density, the obtained bending profile of the NWs is composed of straight (barely-strained) and bent (strained) segments with different lengths which depend on the pitch size. A precise control of the bent and straight NW segment length provides a method to design NW based devices with length selective strain distribution.

One of the most pioneering advantages of the Energy Dispersive X-ray Laue Diffraction (EDLD) is the one-shot experiment for investigation of polycrystalline materials. Using a 2D energy-dispersive detector, the EDLD is measuring simultaneous position- and energy signals. This makes the EDLD a cutting-edge experiment in Micro Texture (MiTx) characterization of polycrystalline materials. However, real-time analysis of the generated images requires innovative techniques to extract grain-wise structural information. Employing synchrotron radiation, high-performance computing, and data management approaches are required to perform one-shot experiments and on-the-fly analysis. In this article we show how the EDLD experimental analysis can be encapsulated with the fast-computing methodology of the in-memory database system, incorporating the cube architecture, and enhancing data accessibility and warehousing.

Organic materials and blends have received a great deal of interests for application in large area, flexible, and low-cost organic/hybrid electronics. In this work the optical, structural and the electrical behaviors of a new active layer system composed by functionalized gold nanoparticles (AuNPs) and conjugated polymers, were investigated. For this purpose, gold nanoparticles with diameter of about 5 nm were chosen, coated with the bifunctional 7C-conjugated ligand (9,9-didodecyl-2,7-bis(acetylthio)fluorene, FL) for their high stability and easy dispersibility in organic solvents. The blends based on AuNPs and regioregular poly-3-hexylthiophene (P3HT) were prepared by adding an increasing percentage by weight of nanoparticles, i.e. from 10% to 90 wt%, in the P3HT polymeric matrix. The presence of nanoparticles was confirmed by UV-Vis spectroscopy, electron microscopy and X-ray diffraction techniques. The optical characterization of the composites demonstrated the possibility to tune the optical behavior of the P3HT by adding increasing percentages of AuNPs into the polymer matrix. Their inclusion results in a loss of P3HT crystallinity and in a simultaneous increase of the 7C-7C interaction between the polythiophene chain and fluorene ligand. To better investigate the films, Grazing Incident X-ray Diffraction (GIXD) measurements were carried out and the blend containing 30 wt% of AuNPs in P3HT reveals an optimal condition, combining good structural order and interconnectivity in the polymer matrix. The electrical characterization of the AuNPs/P3HT blends reveals an improvement of the electrical conductivity in all the prepared blends, that show higher conductivity values compared to the pristine AuNPs and P3HT materials. The best performance is achieved adding 30 wt% of AuNPs to P3HT resulting in an enhancement of conductivity by about 350% compared to that of the pure polymer. This result could be of great interest for the realization of new conductive film composites to use in opto-electronic devices.

Misfit strain in core-shell nanowires can be elastically released by nanowire bending in case of asymmetric shell growth around the nanowire core. In this work, we investigate the bending of GaAs nanowires during the asymmetric overgrowth by an In x Ga1-x As shell caused by avoiding substrate rotation. We observe that the nanowire bending direction depends on the nature of the substrate's oxide layer, demonstrated by Si substrates covered by native and thermal oxide layers. Further, we follow the bending evolution by time-resolved in situ x-ray diffraction measurements during the deposition of the asymmetric shell. The XRD measurements give insight into the temporal development of the strain as well as the bending evolution in the core-shell nanowire.

Here we report on non-uniform shell growth of In(x)Ga(1-x)As onto GaAs nanowire (NW) core by molecular beam epitaxy (MBE). The growth was realized on pre-patterned silicon substrates with pitch size (p) ranging from 0.1 um to 10 um. Considering the preferable bending direction with respect to the MBE cells as well as the layout of the substrate pattern, we are able to modify the strain distribution along the NW growth axis and the subsequent bending profile. For NW arrays with high number density, the obtained bending profile of the NWs is composed of straight (barely-strained) and bent (strained) segments with different lengths which depend on the pitch size. A precise control of the bent and straight NW segment length provides a recipe to design NW based devices with length selective strain distribution.

This article reports on energy-dispersive micro Laue (mu Laue) diffraction of an individual gold nanowire that was mechanically deformed in three-point bending geometry using an atomic force microscope. The nanowire deformation was investigated by scanning the focused polychromatic X-ray beam along the nanowire and recording mu Laue diffraction patterns using an energy-sensitive pnCCD detector that permits measurement of the angular positions of the Laue spots and the energies of the diffracted X-rays simultaneously. The plastic deformation of the nanowire was shown by a bending of up to 3.0 +/- 0.1 degrees, a torsion of up to 0.3 +/- 0.1 degrees and a maximum deformation depth of 80 +/- 5 nm close to the position where the mechanical load was applied. In addition, extended Laue spots in the vicinity of one of the clamping points indicated the storage of geometrically necessary dislocations with a density of 7.5 x 10(13) m(-2). While mu Laue diffraction with a non-energy-sensitive detector only gives access to the deviatoric strain, the energy sensitivity of the employed pnCCD offers absolute strain measurements with a resolution of 1%. Here, the residual strain after complete unloading of the nanowire amounted to maximum tensile and compressive strains of the order of +1.2 and -3%, which is comparable to the actual resolution limit. The combination of white-beam mu Laue diffraction using an energy-sensitive pixel detector with nano-mechanical testing opens up new possibilities for the study of mechanical behavior at the nanoscale.

The present finding illuminates the physics of the formation of interfaces of metal based hetero-structures near layer continuous limit as an approach to develop high-efficiency W/B4C multilayer (ML) optics with ML periodicity varying d = 1.86-1.23 nm at a fixed number of layer pairs N = 400. The microstructure of metal layers is tailored near the onset of grain growth to control the surface density of grains resulting in small average sizes of grains to sub-nanometers. This generates concurrently desirable atomically sharp interfaces, high optical contrast, and desirable stress properties over a large number of periods, which have evidence through the developed ML optics. We demonstrate significantly high reflectivities of ML optics measured in the energy range 10-20 keV, except for d = 1.23 nm due to quasi-continuous layers. The reflectivities at soft gamma-rays are predicted.

We investigate the strain evolution and relaxation process as function of increasing lattice mismatch between the GaAs core and surrounding In x Ga1−x As shell in core–shell nanowire heterostructures grown on Si(111) substrates. The dimensions of the core and shell are kept constant whereas the indium concentration inside the shell is varied. Measuring the 224¯ and 22¯0 in-plane Bragg reflections normal to the nanowire side edges and side facets, we observe a transition from elastic to plastic strain release for a shell indium content x > 0.5. Above the onset of plastic strain relaxation, indium rich mounds and an indium poor coherent shell grow simultaneously around the GaAs core. Mound formation was observed for indium contents x = 0.5 and 0.6 by scanning electron microscopy. Considering both the measured radial reflections and the axial 111 Bragg reflection, the 3D strain variation was extracted separately for the core and the In x Ga1−x As shell.

Residual stresses (RSs) in the very high cycle fatigue regime have to be evaluated, as in some cases they are comparable with the applied stress, affecting the fatigue behaviour. In this work, the evolution of RSs in terms of types I, II, and III was investigated for a duplex stainless steel (DSS) during cyclic loading in high and very high cycle fatigue regimes. The results showed that the type I RS can increase the fatigue strength and prolong the fatigue life remarkably while the types II and III RSs varying in micro-scale dominate the micro-crack initiation mechanism of the DSS.

Microstructure of austenitic-ferritic duplex stainless steel loaded in the Very High Cycle Fatigue regime was investigated using microbeam energy-dispersive X-ray Laue diffraction. Scanning electron microscopy analysis of the surface shows that damage in the form of fatigue cracks is initiated at grain boundaries assisted by slip bands observed in austenite grains. Energy-dispersive X-ray Laue diffraction was then used to scan a damaged area containing both a fatigue crack and slip bands, in order to measure the changes in microstructure. Results from the X-ray data from the austenite grain indicates slip activation of the most favored slip system tilted by 45° with respect to the external loading direction, dividing the grain into two regions on either side of the slip band. In the ferrite phase, in front of the crack, variations in the angle and energy spectra of the diffraction peaks indicate the presence of lattice curvature and a strain gradient. In regions around the crack, diffraction peaks spatially split into several sub-peaks indicating the presence of fine granular areas separated by polarized dislocation walls. Possible reasons for the observed structural evolution are discussed and the advantages of using energy-dispersive X-ray Laue diffraction in fatigue damage analysis are illustrated.

The impact of electrical current on the structure of single free‐standing Be‐doped GaAs nanowires grown on a Si 111 substrate is investigated. Single nanowires have been structurally analyzed by X‐ray nanodiffraction using synchrotron radiation before and after the application of an electrical current. The conductivity measurements on single nanowires in their as‐grown geometry have been realized via W‐probes installed inside a dual‐beam focused ion beam/scanning electron microscopy chamber. Comparing reciprocal space maps of the 111 Bragg reflection, extracted perpendicular to the nanowire growth axis before and after the conductivity measurement, the structural impact of the electrical current is evidenced, including deformation of the hexagonal nanowire cross section, tilting, and bending with respect to the substrate normal. For electrical current densities below 30 A mm−2, the induced changes in the reciprocal space maps are negligible. However, for a current density of 347 A mm−2, the diffraction pattern is completely distorted. The mean cross section of the illuminated nanowire volume is reconstructed from the reciprocal space maps before and after the application of electrical current. Interestingly, the elongation of two pairs of opposing side facets accompanied by shrinkage of the third pair of facets is found. The variations in the nanowire diameter, as well as their tilt and bending, are confirmed by scanning electron microscopy. To explain these findings, material melting due to Joule heating during voltage/current application accompanied by anisotropic deformations induced by the W‐probe is suggested.

Self-catalyzed GaAs nanowires (NWs) on Si substrates are one of the superior candidates for future electronics and optoelectronics integrated with a silicon electronic platform. To bring the NWs from laboratories to industry, it is essential to further develop their basic science and engineering. In situ growth monitoring plays an important role in understanding the fundamental growth mechanisms influencing the resulting properties of NWs. We report on monitoring the growth of an individual self-catalyzed GaAs NW on a patterned Si substrate by molecular beam epitaxy utilizing a micro X-ray diffraction (XRD) setup. For the first time, the full growth run of a single NW was monitored by XRD over a time span of about 1 h. It was found that the NW growth follows two stages. In the first stage, the NW axial growth is dominant while the NW oscillates within 1 degrees tilt angle with respect to the substrate normal. In the second stage, the NW starts to grow radially maintaining a stable orientation. These findings are explained within a dedicated model. From a technical point of view, our results demonstrate the feasibility of in situ growth experiments with NWs/nanoparticles using synchrotron radiation.

Misfit strain in core-shell nanowires can be elastically released by nanowire bending in case of asymmetric shell growth around the nanowire core. In this work, we investigate the bending of GaAs nanowires during the asymmetric overgrowth by an InxGa1-xAs shell caused by avoiding substrate rotation. We observe that the nanowire bending direction depends on the nature of the substrate's oxide layer, demonstrated by Si substrates covered by native and thermal oxide layers. Further, we follow the bending evolution by time-resolvedin situx-ray diffraction measurements during the deposition of the asymmetric shell. The XRD measurements give insight into the temporal development of the strain as well as the bending evolution in the core-shell nanowire.