Experimental observation of microscopic strain in functional devices has sparked interest in fields ranging from microelectronics to biotechnology, as strain engineering enables tuning of electronic, optical, or elastic properties. Moreover, lattice strain can trigger phase transitions, giving rise to new physical properties and their coupling phenomena. The study of correlations between structure and function requires an experimental technique to quantify the full deformation state in thin films and microstructures on the length scales relevant for nanotechnology. We highlight the capabilities of four- and five-dimensional scanning x-ray diffraction microscopy to fulfill this role through several showcase experiments, demonstrating spatial resolution below 100 nm, high lattice sensitivity <10−5, and full quantification of all nine independent components of the local deformation tensor. Being model-free, nondestructive, universally applicable to crystalline materials and compatible with operando experiments, this characterization technique has potential to bridge gaps in the field of strain engineering. The possibility to design materials properties by introducing elastic lattice strain is a fundamental approach in semiconductor nanotechnology and materials science that enabled breakthroughs in fields ranging from optoelectronics via quantum computing to energy storage. Because elastic strain is a tensor quantity, each component can be tuned to tailor a materials electronic band structure in a different way. The ability to microscopically and nondestructively map each of these components may thus provide an essential tool to understand the structure–property relationship in these materials. This article showcases five-dimensional scanning x-ray diffraction microscopy (SXDM), a synchrotron-based technique that provides strain maps with nanoscale spatial resolution (below 50 nm) and high strain sensitivity (10–5). Unlike conventional methods, SXDM captures the full deformation tensor, including diagonal and shear components, directly and model-free. Its ability to map strain variations without altering the sample and without the need for modeling assumptions makes SXDM an indispensable and gap-bridging technique for advancing next-generation nanotechnologies. By highlighting applications in InGaN thin films, Si/SiGe quantum devices, GeSn microdisks, perovskite solar cells, and battery cathodes, our review demonstrates SXDM’s potential to transform materials characterization and inspire new experimental approaches that lead to a deeper understanding of crystalline materials.

Bragg coherent diffraction imaging (BCDI) is a lens-less technique capable of imaging the strain in a particle in the size range from 20 nm up to several micrometres. This indirect measurement technique, used in X-ray synchrotrons or free-electron lasers all over the world, requires an inversion step using iterative algorithms in order to recover the real-space complex object encoding the particle shape and deformation field. However, artefacts such as scattering peaks called `aliens' from nearby particles can affect the accuracy of the final reconstruction and require meticulous and time-consuming manual masking of the raw data. This becomes problematic for BCDI reconstructions during an experiment and/or for large volumes of data. Here, we explore the potential of machine learning, and specifically clustering techniques, to speed up this procedure while keeping the maximum spatial resolution of the object reconstruction. We also provide a user-friendly Python Jupyter notebook program available on Github.

Surface acoustic wave devices are key components for processing radio frequency signals in wireless communication because these devices offer simultaneously high performance, compact size and low cost. The optimization of the device structure requires a quantitative understanding of energy conversion and loss mechanisms. Here we use stroboscopic full-field diffraction x-ray microscopy to reveal an unanticipated acoustic loss in a prototypical one-port resonator device. A non-uniform acoustic excitation in the active area was responsible for the substantial end and side leakages observed at the design frequency. Quantitative analysis of the strain amplitude using a wave decomposition method allowed the determination of several key device parameters. This high-resolution high-throughput spatiotemporal strain imaging technique is more generally applicable to the study of dynamic strain modulation in nanoscale acoustic, electronic, optical and quantum devices. The high sensitivity allows precise measurement of the strain modulation with picometer-scale amplitude.

The palladium-hydrogen system plays a crucial role in catalysis, hydrogen production and storage, hydrogen embrittlement, and sensing technologies. Understanding the transition of palladium nanocrystals (NCs) from the hydrogen-poor (α) phase to the hydrogen-rich (β) phase is crucial for elucidating hydrogen absorption/desorption mechanisms as well as related phenomena such as hydrogen trapping. In this study, we carefully minimized undesired X-ray beam effects and used in situ Bragg coherent diffraction imaging under electrochemical control to map the strain and lattice parameter distribution within individual palladium NCs across electrochemical potentials relevant to hydrogen absorption and desorption. Lattice parameter changes in both α and β phases are tracked, and reversible strain inversion during the α-to-β phase transition is observed. Through strain and reciprocal space analysis and molecular simulations, a model for the α-to-β phase transition is proposed, which includes a hydrogen-saturated subsurface shell, hydrogen depletion from the α phase during β phase nucleation, and propagation of the β phase in a spherical-cap fashion.

Sample and diffractometer alignment for grazing-incidence X-ray measurements become ever more crucial once the beam and surface area of interest reach the nanometre scale. Here we show how a point of interest on a surface can be kept in the beam while measuring X-ray reflectivity, even if it is not in the centre of rotation, either because of systematic errors or additional unwanted angle-dependent sample movement. This can be achieved by a 1D trajectory scan varying the angle of incidence (θ), the detector angle (2θ) and the position of the sample along one axis in the scattering plane. As an example, we show the results of X-ray reflectivity measured from a 10 × 10 µm Au island using a 90 nm beam. Data analysis is presented which considers the angle-dependent X-ray beam footprint illuminating both the Au island and the surrounding support.

We report a detailed investigation into the response of single BaTiO3 (BTO) nanocrystals under applied electric fields (E-field) using Bragg Coherent Diffraction Imaging (BCDI). Our study reveals pronounced domain wall migration and expansion of a sample measure in situ under applied electric field. The changes are most prominent at the surface of the nanocrystal, where the lack of external strain allows greater domain wall mobility. The observed domain shifts are correlated to the strength and orientation of the applied E-field, following a side-by-side domain model from Suzana et al. Notably, we identified a critical voltage threshold at +10 V, which leads to irreversible structural changes, suggesting plastic deformation. The findings highlight how surface effects and intrinsic defects contribute to the enhanced dielectric properties of BTO at the nanoscale, in contrast to bulk materials, where strain limits domain mobility. These findings deepen our understanding of nanoscale dielectric behaviour and inform the design of advanced nanoelectronic devices.

Palladium hydrogen is a useful model in the study of both hydrogen absorption for energy storage, and lattice gas systems for fundamental thermodynamic models. Using in situ time-resolved X-ray nanodiffraction at the fourth generation Extremely Brilliant Source of the European Synchrotron (ESRF-EBS), the kinetics of hydrogen absorption in individual alpha phase Pd nanoparticles is examined. Hydrogen absorption kinetics in a gas reactor and an electrochemical cell are compared. Combining the individual nanoparticle X-ray measurements with chronoamperometry measurements, the kinetics of the ensemble of Pd nanoparticles on the glassy carbon substrate is compared with kinetics at the single nanoparticle level. Hydrogen absorption in alpha phase Pd in the electrochemical system is found to be slower than that of the gas system. Furthermore, the absorption in the electrochemical system slows down as the electrochemical potential is lowered. This slow down is found to be directly related to the increasing hydrogen absorption per step in electrode potential. Furthermore, differences between absorbed-quantity normalized absorption times is seen between the hydrogen and deuterium absorbates. Sieverts's law of absorption is also shown to hold for individual Pd nanoparticles in the alpha phase.

The core principles and nanoscale mechanisms of ion deintercalation in battery cathode materials remain poorly understood, in particular, the relationship between crystallographic defects (dislocations, small angle grain boundaries, vacancies, etc.) and microscopic features of Li deintercalation. Here, we used operando scanning X-ray diffraction microscopy (SXDM) to investigate the local strain and lattice tilt inhomogeneities inside Li1−xMn1.5Ni0.5O4 cathode crystals (diameter from 1 to 2 µm) during electrochemical delithiation and lithiation. The technique has been combined to operando multi crystal X-ray diffraction (MCXD) to differentiate between inter- and intra-particle heterogeneity in the sample. Operando SXDM revealed three distinct domains within the crystal that displayed metastable angular rotations of the lattice during both of the phase transitions. These rotations, reaching up to 0.4°, likely arise due to a dynamic lattice mismatch between phases with different unit cell parameters coexisting within the particle. The persistent location of tilt boundaries implies the presence of inherent structural defects locally facilitating the defect formation. Residual misorientations were observed in the particle even after the full discharge suggesting an irreversible change of the lattice structure. Tilt boundaries, affecting ionic conductivity, may impede the rate capability and lead to localized strain, stress, and potential capacity fade due to cracking. However, the observed self-healing angular lattice reorganization could enable the coexistence of two phases in a single crystal. Understanding this phenomenon can optimize cathode material microstructure.

Bragg coherent diffraction imaging struggles to phase data from nanocrystals exhibiting large strain inhomogeneities, which significantly limits its applicability across many scientific scenarios. Here, we demonstrate the experimental realization of Bragg coherent modulation imaging, an approach that incorporates wavefront modulation into the diffracted beam, enabling unambiguous structure recovery and resolving highly strained crystals. This method provides a more robust tool for three-dimensional lattice strain measurements in nanocrystals.

The necessity of mapping crystal defects in battery materials after synthesis is crucial in understanding heterogeneity within a single crystal domain and among particles to develop superior crystal quality materials. Numerous imaging techniques have been developed over the past years to study these materials at the nanoscale. However, most of them use electron beams which demand many hours of sample preparation, and they are incompatible with the investigation of batteries under realistic working conditions. Techniques such as Scanning X-ray Diffraction Imaging (Scanning X-ray Diffraction Microscopy) or Bragg Coherent Diffraction Imaging are increasingly available on the latest generation synchrotron sources. Their progressive deployment will allow for a standardized method for imaging crystal lattice imperfections such as lattice tilt and strain in individual particles without any prior sample preparation. In this paper, we exploited Scanning X-ray Diffraction Microscopy to probe the strain variation in single crystals and polycrystalline particles and Bragg Coherent Diffraction Imaging to reconstruct the volume of a single crystal particle. Presented case studies were performed on particles of different active cathode materials ($$ \rm{LiNi_{0.6}Mn_{0.2}Co_{0.2}O_{2}} $$ , $$ \rm{LiNiO_{2}} $$ and $$ \rm{LiMn_{1.5}Ni_{0.5}O_{4}} $$ ); however, these techniques can also be employed on other battery components for a more holistic structural understanding of used materials and (de)lithiation dynamics on the microscale.

The observation of unexpected polarisation textures such as vortices, skyrmions and merons in various oxide heterostructures has challenged the widely accepted picture of ferroelectric domain walls as being Ising-like. Bloch components in the 180 domain walls of PbTiO3 have recently been reported in PbTiO3/SrTiO3 superlattices and linked to domain wall chirality. While this opens exciting perspectives, the ubiquitous nature of this Bloch component remains to be further explored. In this work, we present a comprehensive investigation of domain walls in PbTiO3/SrTiO3 superlattices, involving a combination of first- and second-principles calculations, phase-field simulations, diffuse scattering calculations, and synchrotron based diffuse x-ray scattering. Our theoretical calculations highlight that the previously predicted Bloch polarisation in the 180 domain walls in PbTiO3/SrTiO3 superlattices might be more sensitive to the boundary conditions than initially thought and is not always expected to appear. Employing diffuse scattering calculations for larger systems we develop a method to probe the complex structure of domain walls in these superlattices via diffuse x-ray scattering measurements. Through this approach, we investigate depolarization-driven ferroelectric polarization rotation at the domain walls. Our experimental findings, consistent with our theoretical predictions for realistic domain periods, do not reveal any signatures of a Bloch component in the centres of the 180 domain walls of PbTiO3/SrTiO3 superlattices, suggesting that the precise nature of domain walls in the ultrathin PbTiO3 layers is more intricate than previously thought and deserves further attention.

The observation of unexpected polarization textures such as vortices, skyrmions, and merons in The observation of unexpected polarization textures such as vortices, skyrmions, and merons in various oxide heterostructures has challenged the widely accepted picture of ferroelectric domain various oxide heterostructures has challenged the widely accepted picture of ferroelectric domain walls as being Ising-like. Bloch components in the 180 degrees domain walls of PbTiO3 have recently been walls as being Ising-like. Bloch components in the 180 degrees domain walls of PbTiO3 have recently been reported in PbTiO3/SrTiO3 superlattices and linked to domain wall chirality. While this opens reported in PbTiO3/SrTiO3 superlattices and linked to domain wall chirality. While this opens exciting perspectives, the ubiquity of this Bloch component remains to be further explored. In this exciting perspectives, the ubiquity of this Bloch component remains to be further explored. In this work, we present a comprehensive investigation of domain walls in PbTiO3/SrTiO3 superlattices, work, we present a comprehensive investigation of domain walls in PbTiO3/SrTiO3 superlattices, involving a combination of first- and second-principles calculations, phase-field simulations, diffuse involving a combination of first- and second-principles calculations, phase-field simulations, diffuse scattering calculations, and synchrotron-based diffuse x-ray scattering. Our theoretical calculations scattering calculations, and synchrotron-based diffuse x-ray scattering. Our theoretical calculations highlight that the previously predicted Bloch polarization in the 180 degrees domain walls in PbTiO3/SrTiO3 highlight that the previously predicted Bloch polarization in the 180 degrees domain walls in PbTiO3/SrTiO3 superlattices might be more sensitive to the boundary conditions than initially thought and is not superlattices might be more sensitive to the boundary conditions than initially thought and is not always expected to appear. Employing diffuse scattering calculations for larger systems, we develop always expected to appear. Employing diffuse scattering calculations for larger systems, we develop a method to probe the complex structure of domain walls in these superlattices via diffuse x-ray a method to probe the complex structure of domain walls in these superlattices via diffuse x-ray scattering measurements. Through this approach, we investigate depolarization-driven ferroelectric scattering measurements. Through this approach, we investigate depolarization-driven ferroelectric polarization rotation at the domain walls. Our experimental findings, consistent with our theoretical polarization rotation at the domain walls. Our experimental findings, consistent with our theoretical predictions for realistic domain periods, do not reveal any signatures of a Bloch component in the predictions for realistic domain periods, do not reveal any signatures of a Bloch component in the centers of the 180 degrees domain walls of PbTiO3/SrTiO3 superlattices, suggesting that the precise nature centers of the 180 degrees domain walls of PbTiO3/SrTiO3 superlattices, suggesting that the precise nature of domain walls in the ultrathin PbTiO3 layers is more intricate than previously thought and deserves of domain walls in the ultrathin PbTiO3 layers is more intricate than previously thought and deserves further attention. further attention.

A deep-learning algorithm is proposed for the inpainting of Bragg coherent diffraction imaging (BCDI) patterns affected by detector gaps. These regions of missing intensity can compromise the accuracy of reconstruction algorithms, inducing artefacts in the final result. It is thus desirable to restore the intensity in these regions in order to ensure more reliable reconstructions. The key aspect of the method lies in the choice of training the neural network with cropped sections of diffraction data and subsequently patching the predictions generated by the model along the gap, thus completing the full diffraction peak. This approach enables access to a greater amount of experimental data for training and offers the ability to average overlapping sections during patching. As a result, it produces robust and dependable predictions for experimental data arrays of any size. It is shown that the method is able to remove gap-induced artefacts on the reconstructed objects for both simulated and experimental data, which becomes essential in the case of high-resolution BCDI experiments.

Solid-state reactions play a key role in materials science. The evolution of the structure of a single 350 nm Ni3Fe nanoparticle, i.e., its morphology (facets) as well as its deformation field, has been followed by applying multireflection Bragg coherent diffraction imaging. Through this approach, we unveiled a demixing process that occurs at high temperatures (600 degrees C) under an Ar atmosphere. This process leads to the gradual emergence of a highly strained core-shell structure, distinguished by two distinct lattice parameters with a difference of 0.4%. Concurrently, this transformation causes the facets to vanish, ultimately yielding a rounded core-shell nanoparticle. This final structure comprises a Ni3Fe core surrounded by a 40 nm Ni-rich outer shell due to preferential iron oxidation. Providing in situ 3D imaging of the lattice parameters at the nanometer scale while varying the temperature, this study & horbar;with the support of atomistic simulations & horbar;not only showcases the power of in situ multireflection BCDI but also provides valuable insights into the mechanisms at work during a solid-state reaction characterized by a core-shell transition.

Understanding the strain dynamic behavior of catalysts is crucial for the development of cost-effective, efficient, stable, and long-lasting catalysts. Using time-resolved Bragg coherent diffraction imaging at the fourth generation Extremely Brilliant Source of the European Synchrotron (ESRF-EBS), we achieved subsecond time resolution during operando chemical reactions. Upon investigation of Pt nanoparticles during CO oxidation, the three-dimensional strain profile highlights significant changes in the surface and subsurface regions, where localized strain is probed along the [111] direction. Notably, a rapid increase in tensile strain was observed at the top and bottom Pt {111} facets during CO adsorption. Moreover, we detected oscillatory strain changes (6.4 s period) linked to CO adsorption during oxidation, where a time resolution of 0.25 s was achieved. This approach allows for the study of adsorption dynamics of catalytic nanomaterials at the single-particle level under operando conditions, which provides insight into nanoscale catalytic mechanisms.

Imposing and controlling strain in materials such as semiconductors or ferroelectrics is a promising way to obtain new or enhance existing properties. Although the field of strain engineering has seen a rapid expansion over the last two decades, straining semiconductor membranes over large areas remains a challenge. A generic way of tuning strain and hence band structure and electric or magnetic properties of any crystalline material can be obtained by compression of a composite structure involving poorly compressible elastomers. Mechanically similar to the principle of a hydraulic press, this work proposes a device and describes analytically a methodology to easily strain macroscopic membranes up to unprecedented values. Using in-situ X-ray diffraction and Raman spectroscopy, we tuned the biaxial strain in silicon membranes up to a value of 2.1 %, paving the way for new studies in the field of strain related physics, from semiconductors to perovskite oxide multiferroics.

Nanoscale strain networks are reported in BaTiO3 (BTO) crystals of 300 nm size using Bragg coherent diffractive imaging. BTO nanocrystals with clear facets were chosen to identify the crystallographic directions, allowing the strain field direction and periodicity to be studied in detail. Stripes of strain were observed, which were both stable and preserved in tetragonal and cubic phases at elevated temperatures, above the tetragonalto-cubic phase transition. A finite element analysis approach was used to simulate the domain structures inside a BTO crystal and to understand the origins of the strain stripes as piezoelectric blocks. A 180 degrees domain model gives a better qualitative match to the experimental images.

A sample environment and manipulation tool is presented for single-particle X-ray experiments in an aqueous environment. The system is based on a single water droplet, positioned on a substrate that is structured by a hydrophobic and hydrophilic pattern to stabilize the droplet position. The substrate can support several droplets at a time. Evaporation is prevented by covering the droplet by a thin film of mineral oil. In this windowless fluid which minimizes background signal, single particles can be probed and manipulated by micropipettes, which can easily be inserted and steered in the droplet. Holographic X-ray imaging is shown to be well suited to observe and monitor the pipettes, as well as the droplet surface and the particles. Aspiration and force generation are also enabled based on an application of controlled pressure differences. Experimental challenges are addressed and first results are presented, obtained at two different undulator endstations with nano-focused beams. Finally, the sample environment is discussed in view of future coherent imaging and diffraction experiments with synchrotron radiation and single X-ray free-electron laser pulses.