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1. Imaging defects in vanadium( iii ) oxide nanocrystals using Bragg coherent diffractive imaging

   https://doi.org/10.1039/D1CE00736J  

   Barringer, Zachary; Jiang, Jie; Shi, Xiaowen; Schold, Elijah; Pateras, Anastasios; Cipiccia, S.; Rau, C.; Shi, Jian; Fohtung, Edwin (January 2021, CrystEngComm)

   null (Ed.)

   Defects in strongly correlated materials such as V 2 O 3 play influential roles on their electrical properties. Understanding the defects' structure is of paramount importance. In this project, we investigate defect structures in V 2 O 3 grown via a flux method. We use AFM to see surface features in several large flake-like particles that exhibit characteristics of spiral growth. We also use Bragg coherent diffractive imaging (BCDI) to probe in 3 dimensions a smaller particle without flake-like morphology and note an absence of the pure screw dislocation characteristic of spiral growth. We identified and measured several defects by comparing the observed local displacement of the crystal, measured via BCDI to well-known models of the displacement around defects in the crystal. We identified two partial dislocations in the crystal. We discuss how defects of different types influence the morphology of V 2 O 3 crystals grown via a flux method. 

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2. Operando Interaction and Transformation of Metastable Defects in Layered Oxides for Na‐Ion Batteries

   https://doi.org/10.1002/aenm.202203654  

   Gorobtsov, Oleg_Yu; Hirsh, Hayley; Zhang, Minghao; Sheyfer, Dina; Nguyen, Long_Hoang_Bao; Matson, Stephanie_D; Weinstock, Daniel; Bouck, Ryan; Wang, Ziyi; Cha, Wonsuk; et al (April 2023, Advanced Energy Materials)

   Abstract Non‐equilibrium defects often dictate the macroscopic properties of materials. They largely define the reversibility and kinetics of processes in intercalation hosts in rechargeable batteries. Recently, imaging methods have demonstrated that transient dislocations briefly appear in intercalation hosts during ion diffusion. Despite new discoveries, the understanding of impact, formation and self‐healing mechanisms of transient defects, including and beyond dislocations, is lacking. Here, operando X‐ray Bragg Coherent Diffractive Imaging (BCDI) and diffraction peak analysis capture the stages of formation of a unique metastable domain boundary, defect self‐healing, and resolve the local impact of defects on ionic diffusion in Na_xNi_1−yMn_yO₂intercalation hosts in a charging sodium‐ion battery. Results, applicable to a wide range of layered intercalation materials due to the shared nature of framework layers, elucidate new dynamics of transient defects and their connection to macroscopic properties, and suggest how to control the nanostructure dynamics. 

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3. Real‐Time Tracking of Nanoscale Morphology and Strain Evolution in Bi ₂ WO ₆ via Operando Coherent X‐Ray Imaging

   https://doi.org/10.1002/adma.202504445  

   Anderson, Jackson; Nazirkar, Nimish P; Ndiaye, Atoumane; Barringer, Julie; Tran, Viet; Bassène, Pascal; Cha, Wonsuk; Jiang, Jie; Shi, Jian; Harder, Ross; et al (September 2025, Advanced Materials)

   Nanostructuring photocatalytic and catalytic materials substantially increases the surface‐to‐volume ratio, thereby exposing a greater number of active sites essential for enhanced catalytic efficiency. However, optimizing these efficiencies requires the non‐destructive,operandointerrogation of individual nanocrystals under realistic catalytic conditions—a capability that has long remained elusive. Here, this challenge is addressed by reporting three‐dimensional imaging of defects, crystal morphology, and strain dynamics in individual Bi₂WO₆(BWO) nanoflakes using Bragg coherent diffractive imaging (BCDI) underoperandotemperature, gas, and light‐driven conditions. It is demonstrated that maintaining a constant temperature of 40°C thermally activates charge carriers, likely enhancing their mobility and reducing recombination rates. Furthermore, an Argon (Ar) gas flow stabilizes the reaction environment, while a mixed Hydrogen–Nitrogen (H₂+ N₂) flow induces a hydrogen‐triggered semiconducting‐to‐metallic (SM) electronic phase transition accompanied by a structural transformation, as supported by density functional theory (DFT) calculations. Both DFT and BCDI analyses reveal that during the SM phase transition, a new structural phase nucleates near defects and propagates inhomogeneously. Notably, the onset of nanoscale cracking is observed, driven by localized strain accumulation and environmental cycling, which increases surface area and potentially introduces new reactive sites. These findings illustrate that combining advanced nanostructuring withoperandoimaging techniques can provide critical insights into the local structural features that govern photocatalytic performance, paving the way for the rational design of next‐generation photocatalytic materials. 

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4. Atomic-Scale Tracking of Topological Defect Motion and Incommensurate Charge Order Melting

   https://doi.org/10.1103/PhysRevX.15.011007  

   Schnitzer, Noah; Goodge, Berit H; Powers, Gregory; Kim, Jaewook; Cheong, Sang-Wook; El_Baggari, Ismail; Kourkoutis, Lena F (January 2025, Physical Review X)

   Charge order pervades the phase diagrams of quantum materials where it competes with superconducting and magnetic phases, hosts electronic phase transitions and topological defects, and couples to the lattice generating intricate structural distortions. Incommensurate charge order is readily stabilized in manganese oxides, where it is associated with anomalous electronic and magnetic properties, but its nanoscale structural inhomogeneity complicates precise characterization and understanding of its relationship with competing phases. Leveraging atomic-resolution variable-temperature cryogenic scanning transmission electron microscopy, we characterize the thermal evolution of charge order as it transforms from its ground state in a model manganite system. We find that mobile networks of discommensurations and dislocations generate phase inhomogeneity and induce global incommensurability in an otherwise lattice-locked modulation. Driving the order to melt at high temperatures, the discommensuration density grows, and regions of order locally decouple from the lattice periodicity. Published by the American Physical Society2025 

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5. Engineering and probing atomic quantum defects in 2D semiconductors: A perspective

   https://doi.org/10.1063/5.0065185  

   Robinson, Joshua A; Schuler, Bruno (October 2021, Applied Physics Letters)

   Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDs) are considered a key materials class to scale microelectronics to the ultimate atomic level. The robust quantum properties in TMDs also enable new device concepts that promise to push quantum technologies beyond cryogenic environments. Mission-critical capabilities toward realizing these goals are the mitigation of accidental lattice imperfections and the deterministic generation of desirable defects. In this Perspective, the authors review some of their recent results on engineering and probing atomic point defects in 2D TMDs. Furthermore, we provide a personal outlook on the next frontiers in this fast evolving field. 

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