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Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge-lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature ([Formula: see text]93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale ([Formula: see text]6 pm to 11 pm) transverse displacements, suggesting that charge-lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative "incommensurate" order in hole-doped oxides.

Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge-lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature ([Formula: see text]93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale ([Formula: see text]6 pm to 11 pm) transverse displacements, suggesting that charge-lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative "incommensurate" order in hole-doped oxides.

The charge density wave material 1T-TaS2 exhibits a pulse-induced insulator-to-metal transition, which shows promise for next-generation electronics such as memristive memory and neuromorphic hardware. However, the rational design of TaS2 devices is hindered by a poor understanding of the switching mechanism, the pulse-induced phase, and the influence of material defects. Here, we operate a 2-terminal TaS2 device within a scanning transmission electron microscope at cryogenic temperature, and directly visualize the changing charge density wave structure with nanoscale spatial resolution and down to 300 μs temporal resolution. We show that the pulse-induced transition is driven by Joule heating, and that the pulse-induced state corresponds to the nearly commensurate and incommensurate charge density wave phases, depending on the applied voltage amplitude. With our in operando cryogenic electron microscopy experiments, we directly correlate the charge density wave structure with the device resistance, and show that dislocations significantly impact device performance. This work resolves fundamental questions of resistive switching in TaS2 devices, critical for engineering reliable and scalable TaS2 electronics. Resistive switching of 1T-TaS2 is promising for next-generation electronics. Here, using in operando electron microscopy, the authors determine that Joule heating drives the switching process, which will aid the engineering of future devices. [ABSTRACT FROM AUTHOR]

Solid-liquid interfaces are important in a range of chemical, physical and biological processes.sup.1-4, but are often not fully understood owing to the lack of high-resolution characterization methods that are compatible with both solid and liquid components.sup.5. For example, the related processes of dendritic deposition of lithium metal and the formation of solid-electrolyte interphase layers.sup.6,7 are known to be key determinants of battery safety and performance in high-energy-density lithium-metal batteries. But exactly what is involved in these two processes, which occur at a solid-liquid interface, has long been debated.sup.8-11 because of the challenges of observing such interfaces directly. Here we adapt a technique that has enabled cryo-transmission electron microscopy (cryo-TEM) of hydrated specimens in biology--immobilization of liquids by rapid freezing, that is, vitrification.sup.12. By vitrifying the liquid electrolyte we preserve it and the structures at solid-liquid interfaces in lithium-metal batteries in their native state, and thus enable structural and chemical mapping of these interfaces by cryo-scanning transmission electron microscopy (cryo-STEM). We identify two dendrite types coexisting on the lithium anode, each with distinct structure and composition. One family of dendrites has an extended solid-electrolyte interphase layer, whereas the other unexpectedly consists of lithium hydride instead of lithium metal and may contribute disproportionately to loss of battery capacity. The insights into the formation of lithium dendrites that our work provides demonstrate the potential of cryogenic electron microscopy for probing nanoscale processes at intact solid-liquid interfaces in functional devices such as rechargeable batteries.Direct observation of the anode-electrolyte interface in a lithium-metal battery, without removing the liquid electrolyte, reveals two types of dendrites, one of which may contribute disproportionately to capacity fade., Author(s): Michael J. Zachman [sup.1] , Zhengyuan Tu [sup.2] , Snehashis Choudhury [sup.3] , Lynden A. Archer [sup.2] [sup.3] , Lena F. Kourkoutis [sup.1] [sup.4] Author Affiliations:(1) School of Applied [...]

Charge-density waves (CDWs) and their concomitant periodic lattice distortions (PLDs) govern the electronic properties in several layered transition-metal dichalcogenides. In particular, 1T-TaS2 undergoes a metal-to-insulator phase transition as the PLD becomes commensurate with the crystal lattice. Here we directly image PLDs of the nearly commensurate (NC) and commensurate (C) phases in thin, exfoliated 1T-TaS2 using atomic resolution scanning transmission electron microscopy at room and cryogenic temperature. At low temperatures, we observe commensurate PLD superstructures, suggesting ordering of the CDWs both in- and out-of-plane. In addition, we discover stacking transitions in the atomic lattice that occur via one-bond-length shifts. Interestingly, the NC PLDs exist inside both the stacking domains and their boundaries. Transitions in stacking order are expected to create fractional shifts in the CDW between layers and may be another route to manipulate electronic phases in layered dichalcogenides. [ABSTRACT FROM AUTHOR]

With nearly complete spin polarization, the ferromagnetic semiconductor europium monoxide could enable next-generation spintronic devices by providing efficient ohmic spin injection into silicon. Spin injection is greatly affected by the quality of the interface between the injector and silicon. Here, we use atomic-resolution scanning transmission electron microscopy in conjunction with electron energy loss spectroscopy to directly image and chemically characterize a series of EuO|Si and EuO|YAlO3 interfaces fabricated using different growth conditions. We identify the presence of europium silicides and regions of disorder at the EuO|Si interfaces, imperfections that could significantly reduce spin injection efficiencies via spin-flip scattering. [ABSTRACT FROM AUTHOR]

The capacity of soil as a carbon (C) sink is mediated by interactions between organic matter and mineral phases. However, previously proposed layered accumulation of organic matter within aggregate organo–mineral microstructures has not yet been confirmed by direct visualization at the necessary nanometer-scale spatial resolution. Here, we identify disordered micrometer-size organic phases rather than previously reported ordered gradients in C functional groups. Using cryo-electron microscopy with electron energy loss spectroscopy (EELS), we show organo–organic interfaces in contrast to exclusively organo–mineral interfaces. Single-digit nanometer-size layers of C forms were detected at the organo–organic interface, showing alkyl C and nitrogen (N) enrichment (by 4 and 7%, respectively). At the organo–mineral interface, 88% (72–92%) and 33% (16–53%) enrichment of N and oxidized C, respectively, indicate different stabilization processes than at organo–organic interfaces. However, N enrichment at both interface types points towards the importance of N-rich residues for greater C sequestration. Historically it has been maintained that soil organic carbon (SOC) is stabilized through interactions with mineral interfaces. Here the authors use cryo-electron microscopy and spectroscopy to show that SOC interactions can also occur between organic forms in patchy, disordered structure. [ABSTRACT FROM AUTHOR]

While lithium ion batteries with electrodes based on intercalation compounds have dominated the portable energy storage market for decades, the energy density of these materials is fundamentally limited. Today, rapidly growing demand for this type of energy storage is driving research into materials that utilize alternative reaction mechanisms to enable higher energy densities. Transition metal compounds are one such class of materials, with storage enabled by "conversion" reactions, where the material is converted to new compound upon lithiation. MoS2 is one example of this type of material that has generated a large amount of interest recently due to its high theoretical lithium storage capacity compared to graphite. Here, cryogenic scanning transmission electron microscopy techniques are used to reveal the atomic‐scale processes that occur during reaction of a model monolayer MoS2 system by enabling the unaltered atomic structure to be determined at various levels of lithiation. It is revealed that monolayer MoS2 can undergo a conversion reaction even with no substrate, and that the resulting particles are smaller than those that form in bulk MoS2, likely due to the more limited 2D diffusion. Additionally, while bilayer MoS2 undergoes intercalation with a corresponding phase transition before conversion, monolayer MoS2 does not. [ABSTRACT FROM AUTHOR]

Charge-density waves (CDWs) and their concomitant periodic lattice distortions (PLDs) govern the electronic properties in several layered transition-metal dichalcogenides. In particular, 1T-TaS2 undergoes a metal-to-insulator phase transition as the PLD becomes commensurate with the crystal lattice. Here we directly image PLDs of the nearly commensurate (NC) and commensurate (C) phases in thin, exfoliated 1T-TaS2 using atomic resolution scanning transmission electron microscopy at room and cryogenic temperature. At low temperatures, we observe commensurate PLD superstructures, suggesting ordering of the CDWs both in- and out-of-plane. In addition, we discover stacking transitions in the atomic lattice that occur via one-bond-length shifts. Interestingly, the NC PLDs exist inside both the stacking domains and their boundaries. Transitions in stacking order are expected to create fractional shifts in the CDW between layers and may be another route to manipulate electronic phases in layered dichalcogenides. [ABSTRACT FROM AUTHOR]

• Characterization of extracellular vesicle (EV) release from human breast cell lines. • SEM shows vesicular structures budding off of membrane tubes driven by HAS3. • Cryo-TEM reveals two EV sub-populations based upon size and structural detail. • EV surface structure is identified as biomarker for MVs compared to exosomes. As interest in the role of extracellular vesicles in cell-to-cell communication has increased, so has the use of microscopy and analytical techniques to assess their formation, release, and morphology. In this study, we evaluate scanning electron microscopy (SEM) and cryo-SEM for characterizing the formation and shedding of vesicles from human breast cell lines, parental and hyaluronan synthase 3-(HAS3)-overexpressing MCF10A cells, grown directly on transmission electron microscopy (TEM) grids. While cells imaged with conventional and cryo-SEM exhibit distinct morphologies due to the sample preparation process for each technique, tubular structures protruding from the cell surfaces were observed with both approaches. For HAS3-MCF10A cells, vesicles were present along the length of membrane protrusions. Once completely shed from the cells, extracellular vesicles were characterized using nanoparticle tracking analysis (NTA) and cryo-TEM. The size distributions obtained by each technique were different not only in the range of vesicles analyzed, but also in the relative proportion of smaller-to-larger vesicles. These differences are attributed to the presence of biological debris in the media, which is difficult to differentiate from vesicles in NTA. Furthermore, we demonstrate that cryo-TEM can be used to distinguish between vesicles based on their respective surface structures, thereby providing a path to differentiating vesicle subpopulations and identifying their size distributions. Our study emphasizes the necessity of pairing several techniques to characterize extracellular vesicles. [ABSTRACT FROM AUTHOR]