Observation of a new type of nanoscale ferroelectric domains, termed as “bubble domains”—laterally confined spheroids of sub‐10 nm size with local dipoles self‐aligned in a direction opposite to the ...macroscopic polarization of a surrounding ferroelectric matrix—is reported. The bubble domains appear in ultrathin epitaxial PbZr0.2Ti0.8O3/SrTiO3/PbZr0.2Ti0.8O3 ferroelectric sandwich structures due to the interplay between charge and lattice degrees of freedom. The existence of the bubble domains is revealed by high‐resolution piezoresponse force microscopy (PFM), and is corroborated by aberration‐corrected atomic‐resolution scanning transmission electron microscopy mapping of the polarization displacements. An incommensurate phase and symmetry breaking is found within these domains resulting in local polarization rotation and hence impart a mixed Néel–Bloch‐like character to the bubble domain walls. PFM hysteresis loops for the bubble domains reveal that they undergo an irreversible phase transition to cylindrical domains under the electric field, accompanied by a transient rise in the electromechanical response. The observations are in agreement with ab‐initio‐based calculations, which reveal a very narrow window of electrical and elastic parameters that allow the existence of bubble domains. The findings highlight the richness of polar topologies possible in ultrathin ferroelectric structures and bring forward the prospect of emergent functionalities due to topological transitions.
Nanoscale spheroid domains—“bubble domains”—sub‐10 nm in lateral size with local dipoles self‐aligned in a direction opposite to the polarization of the surrounding ferroelectric matrix are reported in ultrathin epitaxial ferroelectric heterostructures. Incommensurate dipolar order and symmetry breaking is found within these domains, which leads to local polarization rotation and consequently mixed Néel–Bloch‐like character to the bubble domain walls.
Current state‐of‐the‐art in situ transmission electron microscopy (TEM) characterization technology has been capable of statically or dynamically nanorobotic manipulating specimens, affording ...abundant atom‐level material attributes. However, an insurmountable barrier between material attributes investigations and device‐level application explorations exists due to immature in situ TEM manufacturing technology and sufficient external coupled stimulus. These limitations seriously prevent the development of in situ device‐level TEM characterization. Herein, a representative in situ opto‐electromechanical TEM characterization platform is put forward by integrating an ultra‐flexible micro‐cantilever chip with optical, mechanical, and electrical coupling fields for the first time. On this platform, static and dynamic in situ device‐level TEM characterizations are implemented by utilizing molybdenum disulfide (MoS2) nanoflake as channel material. E‐beam modulation behavior in MoS2 transistors is demonstrated at ultra‐high e‐beam acceleration voltage (300 kV), stemming from inelastic scattering electron doping into MoS2 nanoflakes. Moreover, in situ dynamic bending MoS2 nanodevices without/with laser irradiation reveals asymmetric piezoresistive properties based on electromechanical effects and secondary enhanced photocurrent based on opto‐electromechanical coupling effects, accompanied by real‐time monitoring atom‐level characterization. This approach provides a step toward advanced in situ device‐level TEM characterization technology with excellent perception ability and inspires in situ TEM characterization with ultra‐sensitive force feedback and light sensing.
An in situ opto‐electromechanical transmission electron microscopy characterization platform is first developed by integrating with an ultra‐flexible piezoresistive molybdenum disulfide micro‐cantilever for device‐level electromechanical and opto‐electromechanical mechanism exploration.
The application of solid polymer electrolytes (SPEs) is still inherently limited by the unstable lithium (Li)/electrolyte interface, despite the advantages of security, flexibility, and workability ...of SPEs. Herein, the Li/electrolyte interface is modified by introducing Li2S additive to harvest stable all‐solid‐state lithium metal batteries (LMBs). Cryo‐transmission electron microscopy (cryo‐TEM) results demonstrate a mosaic interface between poly(ethylene oxide) (PEO) electrolytes and Li metal anodes, in which abundant crystalline grains of Li, Li2O, LiOH, and Li2CO3 are randomly distributed. Besides, cryo‐TEM visualization, combined with molecular dynamics simulations, reveals that the introduction of Li2S accelerates the decomposition of N(CF3SO2)2− and consequently promotes the formation of abundant LiF nanocrystals in the Li/PEO interface. The generated LiF is further verified to inhibit the breakage of CO bonds in the polymer chains and prevents the continuous interface reaction between Li and PEO. Therefore, the all‐solid‐state LMBs with the LiF‐enriched interface exhibit improved cycling capability and stability in a cell configuration with an ultralong lifespan over 1800 h. This work is believed to open up a new avenue for rational design of high‐performance all‐solid‐state LMBs.
Based on the atomic visualization of the lithium (Li)/poly(ethylene oxide) (PEO) interface through cryo‐transmission electron microscopy, Li2S additive is revealed to promote the decomposition of LiN(CF3SO2)2 (LiTFSI) to generate uniform LiF nanocrystals in situ, rendering uniform Li deposition and preventing PEO bond cleavage. This optimized interface is promising for PEO‐electrolyte‐based Li metal batteries with significantly improved cycling lifespan.
A new release of the CrysTBox software is introduced. The original toolbox allows for an automated analysis of transmission electron microscope (TEM) images and for crystallographic visualization. ...The existing tools, which are capable of highly precise analyses of high‐resolution TEM images, as well as spot, disc and ring diffraction patterns, are extended to include a tool for automatically measuring TEM sample thickness using convergent beam electron diffraction in a two‐beam approximation. An implementation of geometric phase analysis is newly available, employing one of the existing tools to identify parameters and indices of crystallographic planes depicted in the input image and allowing easier and more accurate analysis. The crystallographic visualization capabilities are extended as well. Along with the simulated diffraction pattern and atomic structure, a stereographic projection and inverse pole figure tool is newly offered. A new tool able to visualize the atomic structure of two different phases and their interface is also introduced.
CrysTBox is a suite of four tools for automated quantitative analysis of transmission electron microscope images and two crystallographic visualization tools. The recent development of this freely available package is described.
The surface oxidation of aluminum is still poorly understood despite its vital role as an insulator in electronics, in aluminum–air batteries, and in protecting the metal against corrosion. Here we ...use atomic resolution imaging in an environmental transmission electron microscope (TEM) to investigate the mechanism of aluminum oxide formation. Harnessing electron beam sputtering we prepare a pristine, oxide-free metal surface in the TEM. This allows us to study, as a function of crystallographic orientation and oxygen gas pressure, the full oxide growth regime from the first oxide nucleation to a complete saturated, few-nanometers-thick surface film.
A new microwave‐enhanced synthesis method for the production of tellurium nanostructures is reported—with control over products from the 1D regime (sub‐5 nm diameter nanowires), to nanoribbons, to ...the 2D tellurene regime—along with a new methodology for local statistical quantification of the crystallographic parameters of these materials at the nanometer scale. Using a direct electron detector and image‐corrected microscope, large and robust 4D scanning transmission electron microscopy datasets for accurate structural analysis are obtained. These datasets allow the adaptation of quantitative techniques originally developed for X‐ray diffraction (XRD) refinement analyses to transmission electron microscopy, enabling the first demonstration of sub‐picometer accuracy lattice parameter extraction while also obtaining both the size of the coherent crystallite domains and the nanostrain, which is observed to decrease as nanowires transition to tellurene. This new local analysis is commensurate with global powder XRD results, indicating the robustness of both the new synthesis approach and new structural analysis methodology for future scalable production of 2D tellurene and characterization of nanomaterials.
Microwave chemistry is demonstrated to be an efficient means to produce 2D tellurium. More impressively, a new characterization technique and analysis methodology are developed which are capable of observing the dimensional transition locally. This transition is evidenced in a marked reduction in nanostrain and recovery of the isotropic strain profile.
Three tools for an automated analysis of electron diffraction pattern and crystallographic visualization are presented. Firstly, diffractGUI determines the zone axis from selected area diffraction, ...convergent beam diffraction or nanodiffraction patterns and allows for indexing of individual reflections. Secondly, ringGUI identifies crystallographic planes corresponding to the depicted rings in the ring diffraction pattern and can select the sample material from a list of candidates. Both diffractGUI and ringGUI employ methods of computer vision for a fast, robust and accurate analysis. Thirdly, cellViewer is an intuitive visualization tool which is also helpful for crystallographic calculations or educational purposes. diffractGUI and cellViewer can be used together during a transmission electron microscopy session to determine the sample holder tilts required to reach a desired zone axis. All the tools offer a graphical user interface. The toolbox is distributed as a standalone application, so it can be installed on the microscope computer and launched directly from DigitalMicrograph (Gatan Inc.).
Ni‐rich LiNi1−x−yMnxCoyO2 (NMC) layered compounds are the dominant cathode for lithium ion batteries. The role of crystallographic defects on structure evolution and performance degradation during ...electrochemical cycling is not yet fully understood. Here, we investigated the structural evolution of a Ni‐rich NMC cathode in a solid‐state cell by in situ transmission electron microscopy. Antiphase boundary (APB) and twin boundary (TB) separating layered phases played an important role on phase change. Upon Li depletion, the APB extended across the layered structure, while Li/transition metal (TM) ion mixing in the layered phases was detected to induce the rock‐salt phase formation along the coherent TB. According to DFT calculations, Li/TM mixing and phase transition were aided by the low diffusion barriers of TM ions at planar defects. This work reveals the dynamical scenario of secondary phase evolution, helping unveil the origin of performance fading in Ni‐rich NMC.
The structural evolution of a Ni‐rich NMC cathode in a solid‐state cell was investigated by in situ transmission electron microscopy. Antiphase boundary (APB) and twin boundary (TB) separating layered phases played an important role in the phase change. Upon Li depletion, the APB extended across the layered structure, while Li/transition metal (TM) ion mixing in the layered phases induced rock‐salt phase formation along the coherent TB.
Nanocrystal Dynamics
In article number 2206911, Feng Yang, Rongming Wang, and co‐workers summarize the state of the art of in situ and environmental transmission electron microscopy (TEM) and recent ...advances in structure dynamics of nanocrystals from three aspects: nucleation and growth, structure evolution, and dynamics in reaction conditions. The mechanistic insights gained by in situ TEM for the evolution of nanocrystals are expected to be useful for the preparation of nanomaterials.
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