查看更多>>摘要：Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and gen-erate renewable fuels.This promising process,however,is limited by its sluggish reaction kinetics and high-cost catalysts.The two-dimensional(2D)transition metal dichalcogenides(TMDCs)have presented great potential as electrocatalytic materials due to their tunable bandgaps,abundant defective active sites,and good chemical stability.Consequently,phase engineering,defect engineering and interface engineering have been adopted to manipulate the electronic structure of TMDCs for boosting their exceptional catalytic performance.Particularly,it is essential to clarify the local structure of catalytically active sites of TMDCs and their structural evolution in catalytic reactions using atomic resolution electron microscopy and the booming in situ technologies,which is beneficial for exploring the underlying reaction mechanism.In this review,the growth regulation,characterization,particularly atomic configurations of active sites in TMDCs are summa-rized.The significant role of electron microscopy in the understanding of the growth mechanism,the controlled synthesis and functional optimization of 2D TMDCs are discussed.This review will shed light on the design and synthesis of novel electrocatalysts with high performance,as well as prompt the application of advanced electron microscopy in the research of materials science.
查看更多>>摘要：Metal halide perovskites(MHPs)are excellent semiconductors that have led to breakthroughs in applications in thin-film solar cells,detectors,and light-emitting diodes due to their remarkable optoelectronic properties and defect tolerance.However,the performance and stability of MHP-based devices are significantly influenced by their microstructures includ-ing the formation of defects,composition fluctuations,structural inhomogeneity,etc.Transmission electron microscopy(TEM)is a powerful tool for direct observation of microstructure at the atomic-scale resolution and has been used to cor-relate the microstructure and performance of MHP-based devices.In this review,we highlight the application of TEM techniques in revealing the microstructures of MHP thin films at the atomic scale.The results provide critical understand-ing of the performance of MHP devices and guide the design of strategies for improving the performance and stability of MHP devices.
查看更多>>摘要：The microstructure significantly influences the superconducting properties.Herein,the defect structures and atomic arrangements in high-temperature Bi2Sr2CaCu2O8+δ(Bi-2212)superconducting wire are directly characterized via state-of-the-art scanning transmission electron microscopy.Interstitial oxygen atoms are observed in both the charge reservoir layers and grain boundaries in the doped superconductor.Inclusion phases with varied numbers of CuO2 layers are found,and twist interfaces with different angles are identified.This study provides insights into the structures of Bi-2212 wire and lays the groundwork for guiding the design of microstructures and optimizing the production methods to enhance superconducting performance.
查看更多>>摘要：Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalco-genides(TMDs)materials and improving device performance to desired properties.However,the methods in defect control currently face challenges with overly large operational areas and a lack of precision in targeting specific defects.Therefore,we propose a new method for the precise and universal defect healing of TMD materials,integrating real-time imaging with scanning transmission electron microscopy(STEM).This method employs electron beam irradiation to stimulate the diffu-sion migration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy(MBE),and heal defects within the diffusion range.This approach covers defect repairs ranging from zero-dimensional vacancy defects to two-dimensional grain orientation alignment,demonstrating its universality in terms of the types of samples and defects.These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEM for defect healing,providing valuable experience for achieving atomic-level precise fabrication of TMD materials.
查看更多>>摘要：The functionalities and diverse metastable phases of multiferroic BiFeO3(BFO)thin films depend on the misfit strain.Although mixed phase-induced strain relaxation in multiphase BFO thin films is well known,it is unclear whether a single-crystalline BFO thin film can accommodate misfit strain without the involvement of its polymorphs.Thus,understanding the strain relaxation behavior is key to elucidating the lattice strain-property relationship.In this study,a correlative strain analysis based on dark-field inline electron holography(DIH)and quantitative scanning transmission electron microscopy(STEM)was performed to reveal the structural mechanism for strain accommodation of a single-crystalline BFO thin film.The nanoscale DIH strain analysis results indicated a random combination of multiple strain states that acted as a primary strain relief,forming irregularly strained nanodomains.The STEM-based bond length measurement of the corresponding strained nanodomains revealed a unique strain accommodation behavior achieved by a statistical combination of multiple modes of distorted structures on the unit-cell scale.The globally integrated strain for each nanodomain was estimated to be close to-1.5％,irrespective of the nanoscale strain states,which was consistent with the fully strained BFO film on the SrTiO3 substrate.Density functional theory calculations suggested that strain accommodation by the combination of metastable phases was energetically favored compared to single-phase-mediated relaxation.This discovery allows a comprehensive understanding of strain accommodation behavior in ferroelectric oxide films,such as BFO,with various low-symmetry polymorphs.
查看更多>>摘要：Recent advances in scanning transmission electron microscopy(STEM)have led to increased development of multi-dimensional STEM imaging modalities and novel image reconstruction methods.This interest arises because the main electron lens in a modern transmission electron microscope usually has a diffraction-space information limit that is signif-icantly better than the real-space resolution of the same lens.This state-of-affairs is sometimes shared by other scattering methods in modern physics and contributes to a broader excitement surrounding multidimensional techniques that scan a probe while recording diffraction-space images,such as ptychography and scanning nano-beam diffraction.However,the contrasting resolution in the two spaces raises the question as to what is limiting their effective performance.Here,we examine this paradox by considering the effects of aberrations in both image and diffraction planes,and likewise separate the contributions of pre-and post-sample aberrations.This consideration provides insight into aberration-measurement techniques and might also indicate improvements for super-resolution techniques.
查看更多>>摘要：High-angle annular dark field(HAADF)imaging in scanning transmission electron microscopy(STEM)has become an indispensable tool in materials science due to its ability to offer sub-A resolution and provide chemical information through Z-contrast.This study leverages large language models(LLMs)to conduct a comprehensive bibliometric analysis of a large amount of HAADF-related literature(more than 41000 papers).By using LLMs,specifically ChatGPT,we were able to extract detailed information on applications,sample preparation methods,instruments used,and study conclusions.The findings highlight the capability of LLMs to provide a new perspective into HAADF imaging,underscoring its in-creasingly important role in materials science.Moreover,the rich information extracted from these publications can be harnessed to develop Al models that enhance the automation and intelligence of electron microscopes.
查看更多>>摘要：Counterdiabatic driving(CD)offers a fast and robust route to manipulate quantum systems,which has widespread applications in quantum technologies.However,for higher-dimensional complex systems,the exact CD term involving the spectral properties of the system is difficult to calculate and generally takes a complicated form,impeding its experimental realization.Recently,many approximate methods have been proposed for designing CD passages in many-body systems.In this topical review,we focus on the CD formalism and briefly introduce several experimental constructions and applications of approximate CD driving in spin-chain models with nuclear magnetic resonance(NMR)systems.
查看更多>>摘要：Magneto-optical traps(MOTs)composed of magnetic fields and light fields have been widely utilized to cool and confine microscopic particles.Practical technology applications require miniaturized MOTs.The advancement of planar optics has promoted the development of compact MOTs.In this article,we review the development of compact MOTs based on planar optics.First,we introduce the standard MOTs.We then introduce the grating MOTs with micron structures,which have been used to build cold atomic clocks,cold atomic interferometers,and ultra-cold sources.Further,we introduce the integrated MOTs based on nano-scale metasurfaces.These new compact MOTs greatly reduce volume and power consumption,and provide new opportunities for fundamental research and practical applications.
查看更多>>摘要：Quantum enhanced metrology has the potential to go beyond the standard quantum limit and eventually to the ultimate Heisenberg bound.In particular,quantum probes prepared in nonclassical coherent states have recently been recognized as a useful resource for metrology.Hence,there has been considerable interest in constructing magnetic quantum sensors that combine high resolution and high sensitivity.Here,we explore a nanoscale magnetometer with quantum-enhanced sensitivity,based on 123Sb(I=7/2)nuclear spin doped in silicon,that takes advantage of techniques of spin-squeezing and coherent control.With the optimal squeezed initial state,the magnetic field sensitivity may be expected to approach 6 aT.Hz-1/2.cm-3/2 and 603 nT.Hz-1/2 at the single-spin level.This magnetic sensor may provide a novel sensitive and high-resolution route to microscopic mapping of magnetic fields as well as other applications.
NETL
NSTL
万方数据