Synchrotron Measurements Research Articles

Influence of Scanning Strategy on Residual Stresses in Laser-Based Powder Bed Fusion Manufactured Alloy 718: Modeling and Experiments.

In additive manufacturing, the presence of residual stresses in produced parts is a well-recognized phenomenon. These residual stresses not only elevate the risk of crack formation but also impose limitations on in-service performance. Moreover, it can distort printed parts if released, or in the worst case even cause a build to fail due to collision with the powder scraper. This study introduces a thermo-mechanical finite element model designed to predict the impact of various scanning strategies in order to mitigate the aforementioned unwanted outcomes. The investigation focuses on the deformation and residual stresses of two geometries manufactured by laser-based powder bed fusion (PBF-LB). To account for relaxation effects during the process, a mechanism-based material model has been implemented and used. Additionally, a purely mechanical model, based on the inherent strain method, has been calibrated to account for different scanning strategies. To assess the predicted residual stresses, high-energy synchrotron measurements have been used to obtain values for comparison. The predictions of the models are evaluated, and their accuracy is discussed in terms of the physical aspects of the PBF-LB process. Both the thermo-mechanical models and the inherent strain method capture the trend of experimentally measured residual stress fields. While deformations are also adequately captured, there is an overall underprediction of their magnitude. This work contributes to advancing our understanding of the thermo-mechanical behavior in PBF-LB and provides valuable insights for optimizing scanning strategies in additive manufacturing processes.

Mapping sensitivity of CVD diamond detector using synchrotron micro-beam

In this project, we conducted micro-beam sensitivity mapping using the Diamond Light Source (DLS) synchrotron. We fabricated three samples with distinct metal contacts: Platinum (HPS-Pt) and Aluminium/Platinum (HPS-Al/Pt) on high-quality single crystal CVD diamond, and Platinum (VS-Pt) on lower purity single crystal CVD diamond. Our objective was to identify the most suitable sample for synchrotron measurements, particularly focusing on the lower purity sample due to its unique characteristics, such as thin nitrogen lines and substrate area.High spatial resolution sensitivity maps were obtained for the lower purity sample using a micro step displacement of up to 10 μm, revealing detailed nitrogen lines. We observed that bias polarity significantly influenced the photocurrent, with negative bias yielding higher photocurrents, possibly due to polarisation effects. Near nitrogen lines, we noted a slow rise time and an increased stabilization time with bias, alongside a prolonged decay to dark current.For the HPS-Al/Pt sample, we found no improvement in current response homogeneity, therefore reliability, with bias; instead, we recorded high dark currents and unstable signals, particularly at negative bias. Conversely, the HPS-Pt sample exhibited a uniform response at both +50V and −50V in the central region of the sensitivity maps. This response became increasingly homogeneous at 100V and further improved up to 200V, suggesting that HPS-Pt is the most suitable candidate for synchrotron measurements.

Comparative study of phyllosilicate surface and sub-surface interlamellar water adsorption through crystal truncation rod modelling

Phyllosilicates are essential materials for novel implementations in two-dimensional based optoelectronic technologies. These naturally occurring minerals exhibitproperties that can be tuned by atomic species proportions, phase coexistence and chemical inclusions. Among these structural modifications, interlamellar water plays a special role in determining those properties, providing physical stability but also ruling out some conditions that are mandatory for device development, such as spatial chemical homogeneity and dielectric figures of merit. In this sense, it is mandatory to examine whether interlamellar water is restricted to surfaces or can also affect the bulk of multi-layered structures. Here, we provide a concise scenario by cross-correlating results from infrared spectroscopy, Kelvin probe microscopy (both bulk-sensitive for insulating samples), and crystal truncation rod synchrotron measurements (sensitive to the topmost layers, with a few lattice parameter thickness). We show that a comparison of talc, phlogopite and clinochlore can be drawn by considering surface, sub-surface and bulk water content provided by our measurements, indicating the role of ionic layers and lateral water segregation to few-layer non-swelling phyllosilicate systems. Our results can directly impact chemical and structural phyllosilicate choices for device implementation, depending on the required functionality.

A nanoscale investigation of the formation of mesostructured zeolites FAU and LTL

Nanostructured materials can be utilised as potential catalysts for the production of platform chemicals and renewable biofuels from biomass derived molecules. The formation of hierarchical meso-microporous zeolites LTL and FAU via the surfactant assisted tandem acid-base post-synthesis treatment has been investigated by time-resolved in situ synchrotron SAXS and WAXS, providing a new insight into the mechanism of the mesostructuring treatment. Based on the results of TEM and in situ synchrotron measurements, a model for the formation of the core-shell structure of LTL zeolite crystals is proposed. Complementary evaluation using FTIR, NMR and nitrogen adsorption, in conjunction with reaction studies on mesostructured zeolites, demonstrated a potential for enhanced catalytic performance of these materials owing to the increased accessibility of the active sites and reduced transport limitations.

In-situ synchrotron diffraction analysis of deformation mechanisms in an AA5083 sheet metal processed by modified equal-channel angular pressing

Severe plastic deformation (SPD) is a process to significantly improve the mechanical properties of materials by grain refinement. For forming at room temperature (RT), higher strengths can thus be achieved; for increased temperatures (HT), greater elongations can be achieved. This great potential has been chiefly applied only on laboratory scale due to a lack of industrial process design. Equal-channel angular pressing (ECAP) offers the possibility to integrate these advantages in industrial processes. This paper investigates a modified ECAP process for aluminum AA5083 sheet metal. Two passes of ECAP for sheet metal and an additional heat treatment were used. To study the material deformation on a micro-scale, in-situ synchrotron measurements at DESY (Hamburg) were performed to analyze the evolution of lattice strains and dislocation densities during tensile testing. The mechanical properties of the ECAP-processed sheet material reveal an increase in yield strength and a decrease in elongation at RT. Higher strains can be measured for the processed material at elevated test temperatures. In-situ diffraction results show a changed behavior of the ECAP sheet material compared to the reference material for both temperature regimes. These changes are based on the increased defect density in the material, which leads to increased strength at RT. At HT, dynamic recrystallization occurs during tensile testing, and the prevailing deformation mechanisms reconfigure. Electron backscatter diffraction (EBSD) and micrographs are used to interpret and supplement the observations. The findings provide the basis for the in-depth understanding of the deformation behavior of the material and help to apply the ECAP process on an industrial scale.

All-Solid-State Battery Safety Investigation in Calorimeter Coupled with Fast X-Ray Radiography

All-solid-state battery (ASSB) are expected to be a solution to increase energy density in Li-ion technology. However, high-energy storage capacities make the safety a crucial issue. The main reactions leading to thermal runaway in conventional LiB are anode/electrolyte at 110 °C, electrolyte decomposition at 150 °C and cathode/electrolyte at 300 °C. Therefore, without liquid electrolyte, it can be expected that ASSB are less likely to have a thermal runaway.To assess safety of such non-fully mature battery technologies, a new methodology is proposed and a closed calorimeter was designed to perform operando experiments in abuse conditions with high-speed synchrotron X-ray radiography and measurement of temperature, pressure and energy. The data and image of thermal runaway of all-solid-state batteries are presented and compared to the result of Li-ion batteries with liquid electrolyte. An 11 % decrease of heat release was measured for cell with solid electrolyte. Gas volume, amount of matter that reacts in the cell and reaction kinetics have also been compared.Such a methodology allows deepening hypotheses on associated material degradation and that can assist in development of new battery technologies, by evaluating battery safety from the start of the design from battery composition to cell shape.

MiniMelt: An instrument for real-time tracking of electron beam additive manufacturing using synchrotron x-ray techniques.

The development of a sample environment for in situ x-ray characterization during metal Electron Beam Powder Bed Fusion (PBF-EB), called MiniMelt, is presented. The design considerations, the features of the equipment, and its implementation at the synchrotron facility PETRA III at Deutsches Elektronen-Synchrotron, Hamburg, Germany, are described. The equipment is based on the commercially available Freemelt ONE PBF-EB system but has been customized with a unique process chamber to enable real-time synchrotron measurements during the additive manufacturing process. Furthermore, a new unconfined powder bed design to replicate the conditions of the full-scale PBF-EB process is introduced. The first radiography (15kHz) and diffraction (1kHz) measurements of PBF-EB with a hot-work tool steel and a Ni-base superalloy, as well as bulk metal melting with the CMSX-4 alloy, using the sample environment are presented. MiniMelt enables time-resolved investigations of the dynamic phenomena taking place during multi-layer PBF-EB, facilitating process understanding and development of advanced process strategies and materials for PBF-EB.

Exploring high-throughput synchrotron X-Ray powder diffraction for the structural analysis of pharmaceuticals

Synchrotron radiation offers a host of advanced properties, surpassing conventional laboratory sources with its high brightness, tunable phonon energy, photon beam coherence for advanced X-ray imaging, and a structured time profile, ideal for capturing dynamic atomic and molecular processes. However, these benefits come at the cost of operational complexity and expenses. Three decades ago, synchrotron radiation facilities, while technically open to all scientists, primarily served a limited community. Despite substantial accessibility improvements over the past two decades, synchrotron measurements still do not qualify as routine analyses. The intrinsic complexity of synchrotron science means experiments are pursued only when no alternatives suffice. In recent years, strides have been made in technology transfer offices, intermediate synchrotron-based analytical service companies, and the development of high-throughput synchrotron systems at various facilities, reshaping the perception of synchrotron science. This article investigates the practical application of synchrotron X-Ray Powder Diffraction (s-XRPD) techniques in pharmaceutical analysis. By utilizing concrete examples, we demonstrate how high-throughput systems have the potential to revolutionize s-XRPD applications in the pharmaceutical industry, rapidly generating XRPD patterns of comparable or superior quality to those obtained in state-of-the-art laboratory XRPD, all in less than 5 s. Additional cases featuring well-established pharmaceutical active ingredients (API) and excipients substantiate the concept of high throughput in pharmaceuticals, affirming data quality through structural refinements aligned with literature-derived unit cell parameters. Synchrotron data need not always be state-of-the-art to compete with lab-XRPD data. The key lies in ensuring user-friendliness, reproducibility, accessibility, cost-effectiveness, and the streamlined efforts associated with synchrotron instrumentation to remain highly competitive with their laboratory counterparts.

Photoionization of Se2+ and S4+ ions using the screening constant per unit nuclear charge method

Photoionization of Se2+ and S4+ ions are studied in this paper. Accurate resonance energies and quantum defects of the 4s4p2 (3P2, 1D2) 4 s → 4s4p2(2D5/2)np, and 4s24p (3P1, 3P2,1D2) 4p → 4s24p(2P3/2)nd Rydberg transitions in Se2+ are reported. In addition precise energies and quantum defects belonging to the resonances arising from 2p → nd (1P1, 3D1) and 2p → ns (1P1, 3D1) excitations in ground state (1S0) S4+ and to the 1s22s22p63s2 1S0 → 1s22s2p63s2np 1P1 transitions in S4+are tabulated. Calculations are performed in the framework of the Screening constant per unit nuclear charge (SCUNC) method. The SCUNC semi-empirical formulas reproduce excellently the existing synchrotron radiation measurements on Se2+ [Esteves et al., 2015. Phys. Rev. A. 92, 063424]. Furthermore, the present results agree excellently with the synchrotron measurements and MCDF and R-matrix calculations on S4+ [Mosnier et al., 2022. Phys. Rev. A. 106, 033113]. The new SCUNC data tabulated up to n = 50 may be useful reference data suitable for incorporation into astrophysical modeling codes.

An in-Situ Study of the Transformation of Hybrid Layered Hydroxides into Metallic Nanocomposites with Interest in Energy Storage Systems

The high increase of energy demand in recent decade and the necessity of reduce the fossil fuel consumption have triggered the interest of the scientific community in the search of 'green' alternatives. Due to the characteristic intermittence of solar and wind technologies, there is a huge effort on the development energy storage systems. Among them hybrid capacitors (HCs) are promising systems due its high energy and power density values, in comparison with Li-ion batteries, that make them ideal for industrial and automobile applications. Battery-like materials such as nanocomposites (NCs) based on metallic nanoparticles (working as pseudo-capacitor based in redox reactions) with a carbon matrix (working as electric double layer capacitors) are key HCs systems itself. These NCs exhibits a notorious enhancement on their electrochemical performance by applying an external magnetic field. [1] Typically, NCs are obtained by the thermal decomposition of hybrid materials under inert atmosphere, as it has been demonstrated for the case of layered double hydroxides (LDHs), layered hydroxides (α-LHs) and metal organic frameworks (MOFs). [1-3] However, there is a lack of information in terms how the thermal transformation takes places.In this work, we present for the first-time an in-situ study about the transformation of hybrid layered hydroxides into NCs. For that, synchrotron measurements of X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) are performed for different hybrid layered hydroxides to follow the transformation in terms of oxidation state and crystallinity. These hybrid layered hydroxides will variate on: (i) the layered hydroxide structure and the anion-layer interactions (LDHs vs α-LHs + electrostatic vs covalent), (ii) the cation nature, and (iii) the identity of the organic linkers, to name a few. For instance, in the case of α-LHs, while the LHs structure defines the thermal decomposition, and the organic molecule length controls the quality and quantity of the final carbon matrix at the NCs.[4] Interestingly, in function of the amount of carbon present on the organic molecule, the oxidation state and the formation of the carbon matrix on the final material are conditioned, which imply that there is a minimum amount of carbon to obtain the NCs. In the other hand, for the previous NCs obtained, the electrochemical characterization is performed in pouch cells, applying an external magnetic field throughout the galvanostatic cycles. This assembly prevents the loss of material along the time and during the process, where it is evidenced how the magnetic field improves the electrochemical performance with an increase in the specific capacity of the NCs. In overall, this work introduces fundamental knowledge on the rational design of hybrid layered hydroxides and the subsequent nanocomposites and its performance in energy storage systems.

Effect of thermal depolarization on the poling‐induced domain texture and piezoelectric properties in Mg‐doped NBT‐6BT

AbstractRecently, poled Na0.50Bi0.50TiO3‐BaTiO3 (NBT‐BT)‐based polycrystalline materials have been characterized as possessing a high degree of poling‐induced domain texture in their remanent state. This finding is suggested to be the reason for their stable mechanical quality factor at high‐vibration velocity, making them promising candidates for high‐power applications. The materials in consideration are prone to self‐heating and thermal run‐away, particularly at slightly elevated temperatures. Therefore, this paper evaluates the temperature dependence of the poling‐induced domain texture of (Na0.47Bi0.47Ba0.06)TiO3 (NBT‐6BT) doped with 0.5 mol% of Mg as compared to undoped NBT‐6BT. Its influence on small‐signal, large‐signal, and high‐power properties was investigated. To obtain a fundamental understanding of crystal structure, in‐situ synchrotron measurements were conducted as function of temperature to establish a relationship between structure and piezoelectric properties of both Mg‐doped and undoped NBT‐6BT materials.

Time resolved insights into abnormal grain growth by in situ synchrotron measurements

Large oligo-crystalline or single-crystalline metallic materials are of great interest for numerous applications, and a recently developed strategy for promoting abnormal grain growth induced by a cyclic heat treatment opens up new opportunities to manufacture single crystals with a size of several centimeters. So far, the entire available knowledge on this kind of abnormal grain growth has been elaborated based on time discrete observations and, thus, detailed insights into the interplay of elementary mechanisms are still lacking in open literature. The present study reveals time resolved insights into this kind of abnormal grain growth for the first time. It was possible to break down the influence of the individual heat treatment phases by in situ synchrotron high energy X-ray diffraction analysis during cyclic heat treatment. The results obtained not only help to gain a deep understanding of the abnormal grain growth mechanisms, they will also be the basis for an adjustment of the cyclic heat treatment process to improve its efficiency and to eventually obtain even larger single crystals.

Synchrotron radiation-based microcomputed tomography for three-dimensional growth analysis of Aspergillus niger pellets.

Filamentous fungi produce a wide range of relevant biotechnological compounds. The close relationship between fungal morphology and productivity has led to a variety of analytical methods to quantify their macromorphology. Nevertheless, only a µ-computed tomography (µ-CT) based method allows a detailed analysis of the 3D micromorphology of fungal pellets. However, the low sample throughput of a laboratory µ-CT limits the tracking of the micromorphological evolution of a statistically representative number of submerged cultivated fungal pellets over time. To meet this challenge, we applied synchrotron radiation-based X-ray microtomography at the Deutsches Elektronen-Synchrotron[German Electron Synchrotron Research Center], resulting in 19,940 3D analyzed individual fungal pellets that were obtained from 26 sampling points during a 48 hAspergillus niger submerged batch cultivation. For each of the pellets, we were able to determine micromorphological properties such as number and density of spores, tips, branching points, and hyphae. The computed data allowed us to monitor the growth of submerged cultivated fungal pellets in highly resolved 3D for the first time. The generated morphological database from synchrotron measurements can be used to understand, describe, and model the growth of filamentous fungal cultivations.

Experimental Analysis of the Stability of Retained Austenite in a Low‐Alloy 42CrSi Steel after Different Quenching and Partitioning Heat Treatments

Quenching and partitioning (Q&P) steels are characterized by an excellent combination of strength and ductility, opening up great potentials for advanced lightweight components. The Q&P treatment results in microstructures with a martensitic matrix being responsible for increased strength whereas interstitially enriched metastable retained austenite (RA) contributes to excellent ductility. Herein, a comprehensive experimental characterization of microstructure evolution and austenite stability is carried out on a 42CrSi steel being subjected to different Q&P treatments. The microstructure of both conditions is characterized by scanning electron microscopy as well as X‐ray diffraction (XRD) phase analysis. Besides macroscopic standard tensile tests, RA evolution under tensile loading is investigated by in situ XRD using synchrotron and laboratory methods. As a result of different quenching temperatures, the two conditions considered are characterized by different RA contents and morphologies, resulting in different strain hardening behaviors as well as strength and ductility values under tensile loading. In situ synchrotron measurements show differences in the transformation kinetics being rationalized by the different morphologies of the RA. Eventually, the evolution of the phase specific stresses can be explained by the well‐known Masing model.

Implementation of grain mapping by diffraction contrast tomography on a conventional laboratory tomography setup with various detectors.

Laboratory-based diffraction contrast tomography (LabDCT) is a novel technique used to resolve grain orientations and shapes in three dimensions at the micrometre scale using laboratory X-ray sources, allowing the user to overcome the constraint of limited access to synchrotron facilities. To foster the development of this technique, the implementation of LabDCT is illustrated in detail using a conventional laboratory-based X-ray tomography setup, and it is shown that such implementation is possible with the two most common types of detectors: CCD and flat panel. As a benchmark, LabDCT projections were acquired on an AlCu alloy sample using the two types of detectors at different exposure times. Grain maps were subsequently reconstructed using the open-source grain reconstruction method reported in the authors' previous work. To characterize the detection limit and the spatial resolution for the current implementation, the reconstructed LabDCT grain maps were compared with the map obtained from a synchrotron measurement, which is considered as ground truth. The results show that the final grain maps from measurements by the CCD and flat panel detector are similar and show comparable quality, while the CCD gives a much better contrast-to-noise ratio than the flat panel. The analysis of the grain maps reconstructed from measurements with different exposure times suggests that a grain map of comparable quality could be obtained in less than 1 h total acquisition time without a significant loss of grain reconstruction quality and indicates a clear potential for time-lapse LabDCT experiments. The current implementation is suggested to promote the generic use of the LabDCT technique for grain mapping on conventional tomography setups.

Monitoring Amine Intercalation in H3Sb3P2O14 Thin Films Based on Real-Time X-ray Diffraction Data Analysis

Thin films comprised of 2D materials have attracted significant attention, as they can be assembled into novel functional materials. However, to further enhance their application scope, it is necessary to harvest the large property space of 2D materials by fine-tuning them on a molecular level, e.g., by intercalation. In order to fully exploit the potential of intercalated 2D materials and design their properties, it is vital to gain a fundamental understanding of the underlying intercalation mechanism. In this work, we present a method for the quantitative analysis of changes in the peak profile and position observed by in situ synchrotron measurements upon the intercalation of the guest molecule into the layered host. We do this by monitoring the intercalation of n-butylamine (3 M in ethanol) into a H3Sb3P2O14 thin film in real time. Our approach includes a state-of-the-art recursive supercell approach that accounts for peak broadening and shifting caused by randomly occurring intercalation, which enabled quantitative Rietveld refinements of the XRD patterns obtained during the interstratification process. This allowed us to reveal the transient formation of intermediates and the critical role of ethanol, which acts as a vehicle for amine intercalation into the layered host.

Superconductivity arising from pressure-induced emergence of a Fermi surface in the kagome-lattice chalcogenide Rb2Pd3Se4

According to the Bardeen-Cooper-Schrieffer theory, superconductivity usually needs well-defined Fermi surface(s) with strong electron-phonon coupling and moderate quasiparticle density of states. A kagome lattice can host flat bands and topological Dirac bands; meanwhile, due to the parallel Fermi surfaces and saddle points, many interesting orders are expected. Here, we report the observation of superconductivity by pressurizing a kagome compound ${\mathrm{Rb}}_{2}{\mathrm{Pd}}_{3}{\mathrm{Se}}_{4}$ using a diamond-anvil-cell. The parent compound shows an insulating behavior; however, it gradually becomes metallic and turns to a superconducting state when high pressure is applied. High-pressure synchrotron measurements show that there is no structural transition occurring during this process. The density-functional-theory calculations illustrate that the insulating behavior of the parent phase is due to the crystalline field splitting of the partial $\mathrm{Pd}\text{\ensuremath{-}}4d\phantom{\rule{0.16em}{0ex}}{t}_{\text{2g}}$ bands and the Se-derivative $4p$ band. However, the threshold of metallicity and superconductivity are reached when the Lifshitz transition occurs, leading to the emergence of a tiny Fermi surface at the $\mathrm{\ensuremath{\Gamma}}$ point. Our results point to an unconventional superconductivity and shed light on understanding the electronic evolution of a kagome material.

Synchrotron-based techniques for characterizing STCH water-splitting materials

Understanding the role of oxygen vacancy–induced atomic and electronic structural changes to complex metal oxides during water-splitting processes is paramount to advancing the field of solar thermochemical hydrogen production (STCH). The formulation and confirmation of a mechanism for these types of chemical reactions necessitate a multifaceted experimental approach, featuring advanced structural characterization methods. Synchrotron X-ray techniques are essential to the rapidly advancing field of STCH in part due to properties such as high brilliance, high coherence, and variable energy that provide sensitivity, resolution, and rapid data acquisition times required for the characterization of complex metal oxides during water-splitting cycles. X-ray diffraction (XRD) is commonly used for determining the structures and phase purity of new materials synthesized by solid-state techniques and monitoring the structural integrity of oxides during water-splitting processes (e.g., oxygen vacancy–induced lattice expansion). X-ray absorption spectroscopy (XAS) is an element-specific technique and is sensitive to local atomic and electronic changes encountered around metal coordination centers during redox. While in operando measurements are desirable, the experimental conditions required for such measurements (high temperatures, controlled oxygen partial pressures, and H2O) practically necessitate in situ measurements that do not meet all operating conditions or ex situ measurements. Here, we highlight the application of synchrotron X-ray scattering and spectroscopic techniques using both in situ and ex situ measurements, emphasizing the advantages and limitations of each method as they relate to water-splitting processes. The best practices are discussed for preparing quenched states of reduction and performing synchrotron measurements, which focus on XRD and XAS at soft (e.g., oxygen K-edge, transition metal L-edges, and lanthanide M-edges) and hard (e.g., transition metal K-edges and lanthanide L-edges) X-ray energies. The X-ray absorption spectra of these complex oxides are a convolution of multiple contributions with accurate interpretation being contingent on computational methods. The state-of-the-art methods are discussed that enable peak positions and intensities to be related to material electronic and structural properties. Through careful experimental design, these studies can elucidate complex structure–property relationships as they pertain to nonstoichiometric water splitting. A survey of modern approaches for the evaluation of water-splitting materials at synchrotron sources under various experimental conditions is provided, and available software for data analysis is discussed.

Phase Transition Dynamics in a Complex Oxide Heterostructure.

Understanding the behavior of defects in the complex oxides is key to controlling myriad ionic and electronic properties in these multifunctional materials. The observation of defect dynamics, however, requires a unique probe-one sensitive to the configuration of defects as well as its time evolution. Here, we present measurements of oxygen vacancy ordering in epitaxial thin films of SrCoO_{x} and the brownmillerite-perovskite phase transition employing x-ray photon correlation spectroscopy. These and associated synchrotron measurements and theory calculations reveal the close interaction between the kinetics and the dynamics of the phase transition, showing how spatial and temporal fluctuations of heterointerface evolve during the transformation process. The energetics of the transition are correlated with the behavior of oxygen vacancies, and the dimensionality of the transformation is shown to depend strongly on whether the phase is undergoing oxidation or reduction. The experimental and theoretical methods described here are broadly applicable to insitu measurements of dynamic phase behavior and demonstrate how coherence may be employed for novel studies of the complex oxides as enabled by the arrival of fourth-generation hard x-ray coherent light sources.

Monitoring of the recovery of ion-damaged 4H-SiC with in situ synchrotron X-ray diffraction as a tool for strain-engineering

In situ thermal annealing (673-1273 K) during X-ray diffraction synchrotron measurements was performed to monitor the strain level as a proxy to follow the recovery of 300 keV Ar ion irradiated 4H-SiC single crystals. Results show that, when exposed to Ar ions at a fluence of 6.7 $$\times$$ 10 $$^{14}$$ ions/cm $$^2$$ (0.7 dpa), the material suffers a maximum strain of 12 $$\%$$ that reduces to 2 $$\%$$ after the final anneal at 1273 K. In the same time, the disorder derived from the XRD data also demonstrates a thermal recovery of the crystalline structure. Hence, this work presents ion irradiation as a means to induce specific crystalline order and depth-controlled strain states within a few 100 s of nm window in 4H-SiC.