Electron Energy Loss Spectroscopy Research Articles

Microstructural and micromechanical characterization of Cr diffusion barrier in ATR irradiated U-10Zr metallic fuel

Chromium (Cr) has been recognized as a promising diffusion barrier candidate to mitigate the Fuel Cladding Chemical Interaction (FCCI) failure in metallic fuels for sodium-cooled fast reactor. This paper, for the first time, conducted an in-depth post-irradiation examination of the microstructure and composition evolution, and micromechanics of the Cr diffusion barrier in U-10Zr fuel/HT9 cladding irradiated in the Advanced Test Reactor (ATR) to 8.7% burnup at an averaged Peak Inner Cladding Temperature of 540–550 °C. Transmission Electron Microscope (TEM) characterization confirmed the preferential intergranular diffusion of Zr and U in the Cr diffusion barrier, suggesting that grain boundaries served as fast path for the diffusion of Zr and U into the Cr diffusion barrier. The interaction zone is dominated by nano crystalline α-ZrCr2 Laves phase. Despite the interaction, there is no microcracks being observed in the preserved Cr diffusion barrier and HT9 cladding, serving as a good barrier to mitigate FCCI under the studied in-reactor irradiation conditions. High density cavities in uniform distribution are observed inside Cr grains, nano particles contains Cr, Mn, and O are confirmed by Electron Energy Loss Spectroscopy (EELS) analysis. However, it is unclear whether the cavities will become an issue to the barrier integrity at higher burnup. In-situ Scanning Electron Microscopy (SEM) micro-tensile testing uncovered mechanical softening in the HT9 cladding nearing the Cr diffusion barrier, possibly due to the coarsening of lath structure and carbides precipitates.

Electron backscattering coefficients for Cr, Co, and Pd solids: A Monte Carlo simulation study

We have calculated electron backscattering coefficients, η(Ep), at primary electron energies Ep of 0.1–100 keV for three elemental and intermediate atomic number solids, Cr, Co and Pd, with an up-to-date Monte Carlo simulation model. A relativistic dielectric functional approach is adopted for the calculation of the electron inelastic cross section, where several different datasets of optical energy loss function (ELF) are adopted. The calculated backscattering coefficient is found to be substantially affected by the ELF, where the influence can be seen to follow the f- and ps-sum rules and the resultant energy dependence of electron inelastic mean free path. To understand the uncertainties involved in a comparison with experimental data both the theoretical uncertainty due to the elastic cross-section model and the experimental systematic error for the contaminated surfaces are investigated. A total of 192 different scattering potentials are employed for the calculation of Mott's electron elastic cross section and this theoretical uncertainty is confirmed to be small. On the other hand, the simulation of contaminated Co and Pd surfaces with several carbonaceous atomic layers can well explain the experimental data. The present results indicate that accurate backscattering coefficient data should be either measured from fully cleaned surfaces or obtained from modern Monte Carlo theoretical calculations involving reliable optical constants data. With the recent progress in the accurate measurement of optical constants by reflection electron energy loss spectroscopy technique, constructing a reliable theoretical database of electron backscattering coefficients for clean surfaces of elemental solids is highly hopeful.

Electron Energy-Loss Spectroscopy Method for Thin-Film Thickness Calculations with a Low Incident Energy Electron Beam

In this study, the thickness of a thin film (tc) at a low primary electron energy of less than or equal to 10 keV was calculated using electron energy-loss spectroscopy. This method uses the ratio of the intensity of the transmitted background spectrum to the intensity of the transmission electrons with zero-loss energy (elastic) in the presence of an accurate average inelastic free path length (λ). The Monte Carlo model was used to simulate the interaction between the electron beam and the tested thin films. The total background of the transmitted electrons is considered to be the electron transmitting the film with an energy above 50 eV to eliminate the effect of the secondary electrons. The method was used at low primary electron energy to measure the thickness (t) of C, Si, Cr, Cu, Ag, and Au films below 12 nm. For the C and Si films, the accuracy of the thickness calculation increased as the energy of the primary electrons and thickness of the film increased. However, for heavy elements, the accuracy of the film thickness calculations increased as the primary electron energy increased and the film thickness decreased. High accuracy (with 2% uncertainty) in the measurement of C and Si thin films was observed at large thicknesses and 10 keV, where tλ≈1. However, in the case of heavy-element films, the highest accuracy (with an uncertainty below 8%) was found for thin thicknesses and 10 keV, where tλ≤0.29. The present results show that an accurate film thickness measurement can be obtained at primary electron energy equal to or less than 10 keV and a ratio of tλ≤2. This method demonstrates the potential of low-loss electron energy-loss spectroscopy in transmission electron microscopy as a fast and straightforward method for determining the thin-film thickness of the material under investigation at low primary electron energies.

Nanoscale study on the initial stages of the interdiffusion across the amorphous/crystalline interface of poly(methyl methacrylate)/poly(vinylidene fluoride) (PMMA/PVDF) via STEM plus EDX/EELS

Interdiffusion across the interface of poly(methyl methacrylate)/poly(vinylidene fluoride) (PMMA/PVDF) was investigated thoroughly by scanning transmission electron microscopy (STEM) plus electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectrometry (EDX) and further with the assistance of laser-Raman spectroscopy. The factors of the annealing temperature and the time on the interfacial widths and the concentration profiles of PMMA and PVDF across the interface of PMMA/PVDF have been considered in detail. It was found that the concentration profiles of PMMA and PVDF were determined by the crystallization of PVDF, especially at the high annealing temperature (220 °C) in the PMMA part of the interface. Under the influence of the PVDF crystallization, the concentration profiles of F (from PVDF) and O (from PMMA) monitored by STEM-EDX/EELS changed gradually from parabola-shape to linear-shape in the PMMA part. The activation energy for the interdiffusion across the interface of PMMA/PVDF was calculated to be 51.0 kJ/mol, lower than the other reported pairs like poly(vinyl chloride)/poly(ε-caprolactone) (PVC/PCL) (69.8 kJ/mol) and poly(styrene-ran-acrylonitrile)/poly(methyl methacrylate) (SAN-29/PMMA) (175 ± 15 kJ/mol).

Fabrication of monolayer h-BN/LaB6 heterostructure thin film with low work function and high chemical stability

To expand the applications of low work function materials, high chemical stability is necessary to prevent the surface from unfavorable reactions. We developed a 20-nm-thick lanthanum hexaboride (LaB6) thin film covered by a monolayer hexagonal boron nitride (h-BN), which exhibits not only low work function but also high chemical stability. Results demonstrated that the h-BN/LaB6 heterostructure can be formed by vacuum annealing a nitrogen-doped LaB6 thin film. The formation process was investigated using Auger electron spectroscopy (AES), high-resolution electron energy loss spectroscopy (HREELS), and X-ray absorption near edge structure (XANES) spectroscopy. We have elucidated that the doped nitrogen atoms and boron atoms in the film thermally diffuse into the surface during annealing, thereby forming the monolayer h-BN on the surface. Work function was measured using scanning tunneling microscopy (STM). From a practical perspective, chemical stability was evaluated with a heating temperature necessary for restoring the low work function state after air exposure. The work function was comparable to that of the clean LaB6(100) surface. Moreover, it recovered at a much lower temperature than the cleaning temperature of the LaB6(100) surface. We anticipate that this material development will facilitate implementation of the low work function material.

Visualization of oxygen vacancies and self-doped ligand holes in La3Ni2O7-δ.

The recent discovery of superconductivity in La3Ni2O7-δ under high pressure with a transition temperature around 80 K (ref. 1) has sparked extensive experimental2-6 and theoretical efforts7-12. Several key questions regarding the pairing mechanism remain to be answered, such as the most relevant atomic orbitals and the role of atomic deficiencies. Here we develop a new, energy-filtered, multislice electron ptychography technique, assisted by electron energy-loss spectroscopy, to address these critical issues. Oxygen vacancies are directly visualized and are found to primarily occupy the inner apical sites, which have been proposed to be crucial to superconductivity13,14. We precisely determine the nanoscale stoichiometry and its correlation to the oxygen K-edge spectra, which reveals a significant inhomogeneity in the oxygen content and electronic structure within the sample. The spectroscopic results also reveal that stoichiometric La3Ni2O7 has strong charge-transfer characteristics, with holes that are self-doped from Ni sites into O sites. The ligand holes mainly reside on the inner apical O and the planar O, whereas the density on the outer apical O is negligible. As the concentration of O vacancies increases, ligand holes on both sites are simultaneously annihilated. These observations will assist in further development and understanding of superconducting nickelate materials. Our imaging technique for quantifying atomic deficiencies can also be widely applied in materials science and condensed-matter physics.

Engineering a Hierarchy of Disorder: A New Route to Synthesize High-Performance 3D Nanoporous All-Carbon Materials*.

A new nanoporous amorphous carbon (NAC) structure that achieves both ultrahigh strength and high electrical conductivity, which are usually incompatible in porous materials is reported. By using modified spark plasma sintering, three amorphous carbon phases with different atomic bonding configurations are created. The composite consisted of an amorphous sp2-carbon matrix mixed with amorphous sp3-carbon and amorphous graphitic motif. NAC structure has an isotropic electrical conductivity of up to 12000Sm-1, Young's modulus of up to ≈5GPa, and Vickers hardness of over 900MPa. These properties are superior to those of existing conductive nanoporous materials. Direct investigation of the multiscale structure of this material through transmission electron microscopy, electron energy loss spectroscopy, and machine learning-based electron tomography revealed that the origin of the remarkable material properties is the well-organized sp2/sp3 amorphous carbon phases with a core-shell-like architecture, where the sp3-rich carbon forms a resilient core surrounded by a conductive sp2-rich layer. This research not only introduces novel materials with exceptional properties but also opens new opportunities for exploring amorphous structures and designing high-performance materials.

Atomic and electronic structures of domain boundaries in LaTiO3 thin films

Domain boundaries in perovskite oxides often exhibit abundant physical properties and phenomena. Here, epitaxial LaTiO3 thin films on (100) SrTiO3 substrates are prepared by pulsed-laser deposition. X-ray diffraction and transmission electron microscopy investigations reveal that the epitaxial LaTiO3 thin films have good crystallinity but a high density of domain boundaries. Atomic-scale scanning transmission electron microscopy observations reveal that two types of domain boundaries are formed in the LaTiO3 thin films. The type I domain boundaries are formed on the {100} crystal planes, while the type II domain boundaries on the {110} crystal planes. Electron energy-loss spectroscopy analyses suggest that the valence states of Ti ions at the type I domain boundaries are +3, while those at the type II domain boundaries are +4. First-principles calculations reveal that the bandgap decreases at both domain boundaries compared to the bulk. The carrier concentration at the type I domain boundaries is significantly higher than that of the bulk, while the carrier concentration at the type II domain boundaries is lower. These findings suggest that domain boundaries play an important role in tailoring the electrical properties of the LaTiO3 thin films, thereby promoting the potential applications and property modulation of related materials and devices.

Single atoms and metal nanoclusters anchored to graphene vacancies

Fabricating dispersed single atoms and size-controlled metal nanoclusters remains a difficult challenge due to sintering. Here, we demonstrate that atoms and clusters can be immobilized using atomically clean defect-engineered graphene as the matrix. The graphene is first cleaned of surface contamination with laser heating, after which low-energy Ar irradiation is used to create spatially well-separated vacancies into it. Metal atoms are then evaporated either via thermal or ebeam evaporation onto graphene, where they diffuse until being trapped into a vacancy. The density of embedded structures can be controlled through irradiation dose, and the size of the structures through evaporation time. The resulting structures are confirmed through atomic-resolution scanning transmission electron microscopy and electron energy loss spectroscopy. We demonstrate here incorporation of Al, Ti, Fe, Ag and Au single atoms or nanoclusters, but the method should work equally well for other elements.

Chemical Environment and Structural Variations in High Entropy Oxide Thin Film Probed with Electron Microscopy.

We employ analytical transmission electron microscopy (TEM) to correlate the structural and chemical environment variations within a stacked epitaxial thin film of the high entropy oxide (HEO) Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (J14), with two layers grown at different substrate temperatures (500 and 200 °C) using pulsed laser deposition (PLD). Electron diffraction and atomically resolved STEM imaging reveal the difference in out-of-plane lattice parameters in the stacked thin film, which is further quantified on a larger scale using four-dimensional STEM (4D-STEM). In the layer deposited at a lower temperature, electron energy loss spectroscopy (EELS) mapping indicates drastic changes in the oxidation states and bonding environment for Co ions, and energy-dispersive X-ray spectroscopy (EDX) mapping detects more significant cation deficiency. Ab initio density functional theory (DFT) calculations validate that vacancies on the cation sublattice of J14 result in significant electronic and structural changes. The experimental and computational analyses indicate that low temperatures during film growth result in cation deficiency, an altered chemical environment, and reduced lattice parameters while maintaining a single phase. Our results demonstrate that the complex correlation of configurational entropy, kinetics, and thermodynamics can be utilized for accessing a range of metastable configurations in HEO materials without altering cation proportions, enabling further engineering of functional properties of HEO materials.

Electronic effect on the L3,2 edges generated by Cu 3d and O 1s orbitals in CuO nanofibers, pure and doped with Mn.

The present work reports a comparative study on CuO and 3.0% Mn-doped CuO nanofibers (NFs) produced by the electrospinning method. State-of-the-art characterization techniques such as Electron Energy Loss Spectroscopy (EELS) and X-Ray photoelectron Spectroscopy (XPS) have been employed to determine the multivalent states and elucidate their electronic structure at the Cu-L3,2 (2p) edge. The CASTEP code has been used to model CuO (P1) and Mn-doped (C 2/c) with the GGA-PBE functional on the supercomputing system with the Xeon10 module (10 nuclei). Structural characterization was done by using a CM 200 Philips Transmission Electron Microscope (TEM) and the chemical state of surfaces with ESCALAB 250Xi XPS Thermoscientific TM. The NFs present an indirect energy bandgap, Eg = 2.03 eV and 2.85 eV, respectively. The results show that the Cu-L3,2 edge presents degenerate states associated with Cu 2p - O and Cu 3d - O hybridization, indicated as Cu3+.

Tilting and Distortion in the Multiferroic Aurivillius Phase Bi6Ti3Fe1.5Mn0.5O18.

Aurivillius structured Bi6Ti3Fe1.5Mn0.5O18 (B6TFMO) has emerged as a rare room temperature multiferroic, exhibiting reversible magnetoelectric switching of ferroelectric domains under cycled magnetic fields. This layered oxide presents exceptional avenues for advancing data storage technologies owing to its distinctive ferroelectric and ferrimagnetic characteristics. Despite its immense potential, a comprehensive understanding of the underlying mechanisms driving multiferroic behavior remains elusive. Herein, we employ atomic resolution electron microscopy to elucidate the interplay of octahedral tilting and atomic-level structural distortions within B6TFMO, associating these phenomena with functional properties. Fundamental electronic features at varying bonding environments within this complex system are scrutinized using electron energy loss spectroscopy (EELS), revealing that the electronic nature of the Ti4+ cations within perovskite BO6 octahedra is influenced by position within the Aurivillius structure. Layer-by-layer EELS analysis shows an ascending crystal field splitting (Δ) trend from outer to center perovskite layers, with an average increase in Δ of 0.13 ± 0.06 eV. Density functional theory calculations, supported by atomic resolution polarization vector mapping of B-site cations, underscore the correlation between the evolving nature of Ti4+ cations, the extent of tetragonal distortion and ferroelectric behavior. Integrated differential phase contrast imaging unveils the position of light oxygen atoms in B6TFMO for the first time, exposing an escalating degree of octahedral tilting toward the center layers, which competes with the magnitude of BO6 tetragonal distortion. The observed octahedral tilting, influenced by B-site cation arrangement, is deemed crucial for juxtaposing magnetic cations and establishing long-range ferrimagnetic order in multiferroic B6TFMO.

Reduced-Dimensionality Al Nanocrystals: Nanowires, Nanobars, and Nanomoustaches.

Aluminum nanocrystals created by catalyst-driven colloidal synthesis support excellent plasmonic properties, due to their high level of elemental purity, monocrystallinity, and controlled size and shape. Reduction in the rate of nanocrystal growth enables the synthesis of highly anisotropic Al nanowires, nanobars, and singly twinned "nanomoustaches". Electron energy loss spectroscopy was used to study the plasmonic properties of these nanocrystals, spanning the broad energy range needed to map their plasmonic modes. The coupling between these nanocrystals and other plasmonic metal nanostructures, specifically Ag nanocubes and Au films of controlled nanoscale thickness, was investigated. Al nanocrystals show excellent long-term stability under atmospheric conditions, providing a practical alternative to coinage metal-based nanowires in assembled nanoscale devices.

Singular and Nonsingular Transitions in the Infrared Plasmons of Nearly Touching Nanocube Dimers.

Narrow gaps between plasmon-supporting materials can confine infrared electromagnetic energy at the nanoscale, thus enabling applications in areas such as optical sensing. However, in nanoparticle dimers, the nature of the transition between touching (zero gap) and nearly nontouching (nonzero gap ≲15 nm) regimes is still a subject of debate. Here, we observe both singular and nonsingular transitions in infrared plasmons confined to dimers of fluorine-doped indium oxide nanocubes when moving from touching to nontouching configurations depending on the dimensionality of the contact region. Through spatially resolved electron energy-loss spectroscopy, we find a continuous spectral evolution of the lowest-order plasmon mode across the transition for finite touching areas, in excellent agreement with the simulations. This behavior challenges the widely accepted idea that a singular transition always emerges in the near-touching regime of plasmonic particle dimers. The apparent contradiction is resolved by theoretically examining different types of gap morphologies, revealing that the presence of a finite touching area renders the transition nonsingular, while one-dimensional and point-like contacts produce a singular behavior in which the lowest-order dipolar mode in the touching configuration, characterized by a net induced charge in each of the particles, becomes unphysical as soon as they are separated. Our results provide valuable insights into the nature of dimer plasmons in highly doped semiconductors.

Investigation of the thermal decomposition of Pu(IV) oxalate: a transmission electron microscopy study

The degradation of the internal structure of plutonium (IV) oxalate during calcination was investigated with Transmission Electron Microscopy (TEM), electron diffraction, Electron Energy-Loss Spectroscopy (EELS), and 4D Scanning TEM (STEM). TEM lift-outs were prepared from samples that had been calcined at 300°C, 450°C, 650°C and 950°C. The resulting phase at all calcination temperatures was identified as PuO2 with electron diffraction. The grain size range was obtained with high-resolution TEM. In addition, 4D STEM images were analyzed to provide grain size distributions. In the 300°C calcined sample, the grains were <10 nm in diameter, at 650°C, the grains ranged from 10 to 20 nm, and by 950°C, the grains were 95–175 nm across. Using the Kolmogorov-Smirnov (K-S) two sample test, it was shown that morphological measurements obtained from 4D-STEM provided statistically significant distributions to distinguish samples at the different calcination conditions. Using STEM-EELS, carbon was shown to be present in the low temperature calcined samples associated with oxalate but had formed carbon (possibly graphite) deposits in the 950°C calcined sample. This work highlights the new methods of STEM-EELS and 4D-STEM for studying the internal structure of special nuclear materials (SNM).

Unveiling Variations in Electronic and Atomic Structures Due to Nanoscale Wurtzite and Zinc Blende Phase Separation in GaAs Nanowires.

Phase separation is an intriguing phenomenon often found in III-V nanostructures, but its effect on the atomic and electronic structures of III-V nanomaterials is still not fully understood. Here we study the variations in atomic arrangement and band structure due to the coexistence of wurtzite (WZ) and zinc blende (ZB) phases in single GaAs nanowires by using scanning transmission electron microscopy and monochromated electron energy loss spectroscopy. The WZ lattice distances are found to be larger (by ∼1%), along both the nanowire length direction and the perpendicular direction, than the ZB lattice. The band gap of the WZ phase is ∼20 meV smaller than that of the ZB phase. A shift of ∼70 meV in the conduction band edge between the two phases is also found. The direct and local measurements in single GaAs nanowires reveal important effects of phase separation on the properties of individual III-V nanostructures.

Fast computational approach with prior dimension reduction for three-dimensional chemical component analysis using CT data of spectral imaging.

Spectral image (SI) measurement techniques, such as X-ray absorption fine structure (XAFS) imaging and scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS), are useful for identifying chemical structures in composite materials. Machine-learning techniques have been developed for automatic analysis of SI data, and their usefulness has been proven. Recently, an extended measurement technique combining SI with a computed tomography (CT) technique (CT-SI), such as CT-XAFS and STEM-EDS/EELS tomography, was developed to identify the three-dimensional (3D) structures of chemical components. CT-SI analysis can be conducted by combining CT reconstruction algorithms and chemical component analysis based on machine learning techniques. However, this analysis incurs high computational costs owing to the size of the CT-SI datasets. To address this problem, this study proposed a fast computational approach for 3D chemical component analysis in an unsupervised learning setting. The primary idea for reducing the computational cost involved compressing the CT-SI data prior to CT computation and performing 3D reconstruction and chemical component analysis on the compressed data. The proposed approach significantly reduced the computational cost without losing information about the 3D structure and chemical components. We experimentally evaluated the proposed approach using synthetic and real CT-XAFS data, which demonstrated that our approach achieved a significantly faster computational speed than the conventional approach while maintaining analysis performance. As the proposed procedure can be implemented with any CT algorithm, it is expected to accelerate 3D analyses with sparse regularized CT algorithms in noisy and sparse CT-SI datasets.

Plasmonic Characterization of 3D Printable Metal-Polymer Nanocomposites.

Plasmonic polymer nanocomposites (i.e., polymer matrices containing plasmonic nanostructures) are appealing candidates for the development of manifold technological devices relying on light-matter interactions, provided that they have inherent properties and processing capabilities. The smart development of plasmonic nanocomposites requires in-depth optical analyses proving the material performance, along with correlative studies guiding the synthesis of tailored materials. Importantly, plasmon resonances emerging from metal nanoparticles affect the macroscopic optical response of the nanocomposite, leading to far- and near-field perturbations useful to address the optical activity of the material. We analyze the plasmonic behavior of two nanocomposites suitable for 3D printing, based on acrylic resin matrices loaded with Au or Ag nanoparticles. We compare experimental and computed UV-vis macroscopic spectra (far-field) with single-particle electron energy loss spectroscopy (EELS) analyses (near-field). We extended the calculations of Au and Ag plasmon-related resonances over different environments and nanoparticle sizes. Discrepancies between UV-vis and EELS are dependent on the interplay between the metal considered, the surrounding media, and the size of the nanoparticles. The study allows comparing in detail the plasmonic performance of Au- and Ag-polymer nanocomposites, whose plasmonic response is better addressed, accounting for their intended applications (i.e., whether they rely on far- or near-field interactions).

Suppressed thermal transport in silicon nanoribbons by inhomogeneous strain.

Nanoscale structures can produce extreme strain that enables unprecedented material properties, such as tailored electronic bandgap1-5, elevated superconducting temperature6,7 and enhanced electrocatalytic activity8,9. While uniform strains are known to elicit limited effects on heat flow10-15, the impact of inhomogeneous strains has remained elusive owing to the coexistence of interfaces16-20 and defects21-23. Here we address this gap by introducing inhomogeneous strain through bending individual silicon nanoribbons on a custom-fabricated microdevice and measuring its effect on thermal transport while characterizing the strain-dependent vibrational spectra with sub-nanometre resolution. Our results show that a strain gradient of 0.112% per nanometre could lead to a drastic thermal conductivity reduction of 34 ± 5%, in clear contrast to the nearly constant values measured under uniform strains10,12,14,15. We further map the local lattice vibrational spectra using electron energy-loss spectroscopy, which reveals phonon peak shifts of several millielectron-volts along the strain gradient. This unique phonon spectra broadening effect intensifies phonon scattering and substantially impedes thermal transport, as evidenced by first-principles calculations. Our work uncovers a crucial piece of the long-standing puzzle of lattice dynamics under inhomogeneous strain, which is absent under uniform strain and eludes conventional understanding.

Electronic Properties of W’ Twin Walls in Ferroelastic BiVO4

AbstractTopological defects in ferroic materials can exhibit intrinsic properties that differ from the bulk. Here， structural and electronic variations of non‐prominent (W’) ferroelastic twin domain walls are investigated in BiVO4, a widely investigated photocatalytic material. Using aberration‐corrected scanning transmission electron microscopy (STEM), a kink configuration of the sharp ferroelastic twin wall with an altered electronic structure is revealed. Nanoscale conductivity measurements by conductive atomic force microscopy (c‐AFM) show higher conductivity at twin walls compared to non‐conductive bulk domains. Electronic structure investigation by electron energy loss spectroscopy (EELS) shows a higher density of oxygen vacancies and possible polaron accumulation at the wall. These findings reveal the electronic properties of BiVO4 domain walls, which are interesting for nanoscale‐engineered catalytic concepts of BiVO4 and materials design for photochemistry‐relevant applications.