High-resolution Transmission Electron Microscopy Images Research Articles

Microbial biosurfactant-mediated green synthesis of zinc oxide nanoparticles (ZnO NPs) and exploring their role in enhancing chickpea and rice seed germination

Malnutrition is one of the greatest challenges faced by humanity, which may be addressed by improving crop productivity to ensure food security. However, extensive use of synthetic fertilizers can lead to soil fertility degradation. This study highlights the potential of combining nanotechnology with biotechnology to enhance the germination rates of commercially important crop seeds. Bacterial biosurfactant extracted from a newly isolated Klebsiella sp. strain RGUDBI03 was used as a reducing and capping agent for the synthesis of zinc oxide nanoparticles (ZnO NPs) through a simple method. Extensive characterization of ZnO NPs through electron microscopic analysis showed well-dispersed, homogeneous NPs with a size range of 2–10 nm. High-resolution transmission electron microscopy (HR-TEM) images also revealed molecular fringes of 0.26 nm in single crystal ZnO NPs, with approximately 50% of the NPs exhibiting a size range of 2–4 nm. X-ray diffraction (XRD) results of ZnO NPs indicated the presence of (100), (002), (101), (102), (200), and (112) planes, confirming their crystalline nature. The presence of C = C–H, C = C, C–H, and C = C groups in both the bacterial biosurfactant and ZnO NPs, as depicted by Fourier-transform infrared spectroscopy (FTIR) spectra, confirmed the function of the biosurfactant as a reducing and capping agent. The nano-primed chickpea (Cicer arietinum) and rice (Oryza sativa) seeds showed an increase in water uptake rate, 89% and 92% respectively, compared to the control (73% and 44%), leading to an enhanced germination rate of 98% and 76%, compared to their respective controls (80% and 30%) under optimized conditions. Additionally, the nano-primed seeds exhibited higher levels of α-amylase activity in both seeds (0.37 mg/g for chickpea and 2.49 mg/g for rice) compared to the control. Notably, the ZnO NP priming solution exhibited no cytotoxicity on red blood cells and earthworms (Eudrilus eugeniae), indicating their non-cytotoxic and eco-friendly nature for future field trials.

Enhancing Semantic Segmentation in High-Resolution TEM Images: A Comparative Study of Batch Normalization and Instance Normalization

Abstract Integrating deep learning into image analysis for transmission electron microscopy (TEM) holds significant promise for advancing materials science and nanotechnology. Deep learning is able to enhance image quality, to automate feature detection, and to accelerate data analysis, addressing the complex nature of TEM datasets. This capability is crucial for precise and efficient characterization of details on the nano—and microscale, e.g., facilitating more accurate and high-throughput analysis of nanoparticle structures. This study investigates the influence of batch normalization (BN) and instance normalization (IN) on the performance of deep learning models for semantic segmentation of high-resolution TEM images. Using U-Net and ResNet architectures, we trained models on two different datasets. Our results demonstrate that IN consistently outperforms BN, yielding higher Dice scores and Intersection over Union metrics. These findings underscore the necessity of selecting appropriate normalization methods to maximize the performance of deep learning models applied to TEM images.

Demonstration of 1 V Reliable FeRAM Operation: Vc Engineering Using Quasi-Chirality of Hf1-xZrxO2 in a Nanolaminate Structure.

Hafnia thin films are known to demonstrate excellent performance with strong ferroelectricity and high scalability, making them promising candidates for CMOS-compatible materials. However, the reliability of ferroelectric devices must be further improved. This study developed a Hf1-xZrxO2 ferroelectric capacitor with a nanolaminate structure that operated at remarkably low voltages, demonstrating excellent retention (>10 years/85 °C) and endurance (>1010 cycles). The exceptional performance is attributed to the presence of thin tetragonal phase layers within the thick ferroelectric layers, which decreased the switching barrier in the nanolaminate films. Further, we verified phase crystallization via a detailed analysis of high-resolution transmission electron microscopy images. The improved switching propagation in the nanolaminate films was confirmed through switching speed measurements and theoretical models. Furthermore, we addressed pinching issues by precisely controlling the Hf/Zr ratio and O3 treatment. The initial imprint and retention characteristics were improved by interfacial engineering. Moreover, by reducing the thickness, we have achieved reliable operation at 1.0 V with a 5.5 nm-thick device while maintaining high retention and endurance. This study is a significant step toward the realization of the longstanding problem of ferroelectric random access memory operation voltage with respect to endurance and retention characteristics.

Nanomineralogy of thorite in the supergiant Huayangchuan uranium ore deposit: Revealing a new geochemical behavior of actinide in environment

Thorium (Th) is a naturally occurring radioactive element found in the environment, and recent advancements have been made in identifying and characterizing Th-bearing nanoparticles (NPs). However, the main focus is still on synthesized Th-bearing NPs and knowledge about natural Th-bearing NPs remains limited. Here, high-resolution transmission electron microscopy (HRTEM) observations of thorite from the Huayangchuan uranium ore deposit in Shaanxi Province, Central China, have revealed the nanoscale mineral characteristics of thorite. In this study, thorite NPs ranging from 5–10 nm in size were identified within the uranium ore. A combination of transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS) elemental mapping and corresponding HRTEM images alongside Selected Area Electron Diffraction (SAED) and Fast Fourier Transform (FFT) patterns revealed a complex nanoscale structure in the thorite NPs, consisting of both amorphous and crystalline nanodomains with abundant defects. These nanostructures are associated with a metamictization mechanism in micrometer-sized thorite. Our findings indicate that the metamictization process can generate numerous thorite nanoparticles. Given the high penetrability and mobility of these NPs, the metamictization of thorite poses new challenges for the long-term stability of radioactive substances and the storage containers for radioactive waste. Furthermore, considering the likelihood of environmental release and the chemical toxicity, radioactivity, and nanotoxicity of natural Th-bearing NPs, increased attention should be given to the presence of natural thorite NPs in the ore deposit.

Direct fabrication of polycrystalline γ-alumina nanochains-supported Pt nanoparticles on macroscopic ceramic substrates

We report the direct fabrication of polycrystalline γ-Al2O3 nanochains-supported Pt nanoparticles on macroscopic substrates, such as monolithic honeycombs and porous disc-typed ceramics, via chemical vapor deposition. We also investigate solid-gas reactions between the γ-Al2O3 nanochains@Pt nanoparticles and CO using in-situ transmission electron microscopy (TEM). The SEM, TEM, STEM, and XRD patterns reveal that γ-Al2O3 nanochains, 80 nm in diameter, were uniformly formed on the surfaces of macroscopic ceramic substrates. High-resolution TEM (HTEM) images confirm the polycrystalline and kinking structures connecting the nanochains. The coating thickness of γ-Al2O3 nanochains layer is approximately 100㎛. The EDX images and XPS graphs indicate that Pt nanoparticles, 3.5 nm in diameter, are well-coated on the surfaces of the γ-Al2O3 nanochains. The uniform distribution of Pt nanoparticles is precisely controlled utilizing autogenic pressure reaction. Additionally, in-situ observation significantly highlights the physicochemical phenomena of the γ-Al2O3 nanochains@Pt nanoparticles over time under CO supply at 300°C. Coke formation was accelerated on the surface of catalysts as increase of CO partial pressure increase, while Pt nanoparticles is very stable without the migration and aggregation.

Enhanced electrochemical performance of K0.67[Ni0.3Mn0.6Co0.1] O2 as a cathode material for secondary K-Ion batteries: Improved K-Ion insertion and reduced charge transfer barrier

Potassium-ion batteries, with their high operating voltage and cost-efficiency, emerged as promising contenders for large-scale energy storage system. Nevertheless, the practical application is hindered by the significant challenges of achieving high capacity and good rate capability in cathodes. Herein, a novel layered oxide cathode, K0.67[Ni0.3Mn0.6Co0.1] O2 (KNMCO), has been synthesized via solid-state (S-KNMCO) and co-precipitation (C-KNMCO) routes. The X-Ray diffraction (XRD) peaks of KNMCO are identified in R3 m space group and well-indexed to hexagonal unit cell. The FE-SEM shows non-spherical morphologies for both samples. Additionally, high-resolution transmission electron microscopy (HR-TEM) images of the synthesized cathode materials shows the interlayer spacing of S-KNMCO is higher than that of C-KNMCO. Furthermore, the electrochemical performance of S-KNMCO and C-KNMCO is characterized using K-metal as anode and electrolyte KPF6 in EC/DEC (1:1, v/v). The S-KNMCO and C-KNMCO exhibit the maximum specific discharge capacity of ∼101 mAhg-1 and ∼66 mAhg-1 at the current rate of C/20 respectively. Additionally, these cells show the good rate capability and coulombic efficiency (∼94%). This research offers novel perspectives on the development of cathode substances for KIBs.

A "Bottom-Up" Strategy for High-Performance Benzocyclobutene (BCB)-Subnanometer Inorganic Nanocomposites.

Developing benzocyclobutene (BCB) nanocomposites with ultra-small inorganic sizes represents a formidable challenge, although it offers great potential to produce materials with customizable structural and rich functional properties. In this study, we present a "bottom-up" design strategy for creating cross-linked benzocyclobutene (BCB) nanocomposites with highly dispersed nanodomains, such as organoalkoxysilane. This approach leverages ring-opening metathesis polymerization (ROMP) and thermally induced cycloaddition reactions to embed oligomeric silsesquioxanes, achieving a unique molecular structure with promising low-dielectric applications. The synthesis involves organoalkoxysilane and BCB as pendant groups of polynorbornenes that are covalently integrated. Additionally, the methoxyl groups of linear polymers could be further hydrolyzed under acidic conditions, and BCB groups could undergo thermal-induced ring-opening at high temperatures and Diels-Alder addition between themselves and vinyl groups, respectively. Fourier transform infrared (FTIR) spectroscopy analyses suggested the presence of ladder or network structures and high-resolution transmission electron microscopy (HRTEM) images presented the well-dispersed inorganic clusters, facilitating excellent dielectric properties with a dielectric constant (Dk) of 2.25 and a dissipation factor (Df) of 2.27 × 10-4. Compared with previously reported low-Dk materials, the cured nanocomposites also exhibited a significantly balanced enhancement of their comprehensive properties. This molecular bottom-up strategy provided a simple and universal method for constructing BCB-inorganic nanocomposites featuring a subnanometer inorganic structure, paving the way for future investigation into new classes of polymer-inorganic nanocomposites with a low Dk.

Exploring novel nanostructural architecture of doubly doped ceria (Ce0.85Sr0.075Sm0.075O2-δ) and barium cerate (BaCeO3) as electrolytes for low-temperature solid oxide fuel cells

This study presents the development of a composite electrolyte for use in low-temperature (300–500 °C) Solid oxide Fuel Cells, focusing on a novel nanostructural design. The electrolyte comprises co-doped ceria (Ce0.85Sr0.075Sm0.075O2-δ, DCO) and barium cerate (BaCeO3, BCO), integrated into a unique nanostructural architecture. Initially, the constituent phases of the composite DCO and BCO are synthesized using a soft-chemical route separately, followed by their integration through liquid mixing technique in various compositions (90:10, 80:20, 70:30, 60:40, 50:50) of DCO:BCO in weight ratio. The composite structure is confirmed by X-ray diffraction, and refined the structural data by Rietveld refinement indicating a structural agreement with cubic and fluorite phases of DCO and BCO, respectively. Scanning Electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal a uniform distribution of two phases with fine size distribution below 50 nm. Transmission Electron microscopy (TEM) images illustrate the core-shell-like integration of the two phases. High-resolution TEM images indicate that the core consists of the DCO phase, while the shell is composed of the BCO phase. The microstructure of sintered pellets exhibits gas-tight densification, with grains dominated by the DCO phase and BCO phase dispersed along grain boundaries. The ionic conductivity of composite systems is extracted from Electrochemical impedance spectroscopy (EIS) studies, showing that DCO-BCO-40 exhibits the highest conductivity 1.132 × 10−3 Scm−1 @400 °C, which is higher than pristine DCO (0.34 × 10−4 Scm−1 @400 °C). Single cells fabricated using DCO-BCO-40 electrolytes deliver a power output of 280 mW cm−2 whereas pristine DCO showed 279 mW @500 °C. This study exhibits the potential of the core-shell-like nanostructural architecture of electrolytes in advancing Low-temperature solid oxide Fuel cell (LT-SOFC) technology and facilitating the transition toward sustainable energy systems.

Controllable growth of large 1T-NbTe2 nanosheets on mica by chemical vapor deposition and its magnetic properties

Two-dimensional (2D) magnetic materials have recently attracted broad attention for their potential technological applications. Here, we report controllable growth of NbTe2 nanosheets on mica substrate by atmospheric chemical vapor deposition. Different from the SiO2/Si substrates, dangling bonds on the surface of the mica are absent, which induces low nucleation density and higher lateral growth rate. As a result, the lateral size of NbTe2 nanosheets on mica substrates can be significantly larger than those on SiO2/Si substrates. Large single crystal NbTe2 nanosheets with a lateral size of up to 151 µm were fabricated on a mica. High-resolution transmission electron microscope image, XRD patterns and Raman spectra reveal the NbTe2 nanosheets adopt the single crystal with 1T phase. Furthermore, the NbTe2 nanosheets on mica demonstrate ferromagnetic properties with a Curie temperature of up to 162 K. Our work paves the way for the atmospheric chemical vapor deposition growth and applications of many more 2D magnets.

TWO IN ONE GRAM NEGATIVE ANTIBACTERIAL AGENT AND ORGANIC DYE PHOTOCATALYST FROM GREEN OCIMUM SANCTUM-BASED CO-DOPED CARBON DOT SILVER NANOCOMPOSITE.

This study reports, successful synthesis of Oxygen(O) and Nitrogen(N) co-doped Ocimum Sanctum plant-based or tulsi carbon dots-silver nanoparticle nanocomposites (TCD-AgNP) for the development of an efficient, highly active, low-cost fingerprint antibacterial agent against gram-negative organisms and a highly efficient photocatalyst for the degradation of methylene blue (MB). The novelty and advantage of this study is the development of highly stable, blue fluorescent, high quantum yield (40%) environmental -friendly TCD-AgNP nanocomposite through reduction method by using green TCDs. Spectrochemical characteristics of synthesized TCDs and TCD-AgNP nanocomposites were investigated through UV-Vis absorbance, Photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and Zeta potential measurements confirming excellent fluorescence, unique stability and effective O and N doping. High-resolution transmission electron microscopy (HR-TEM) images confirms that the synthesized TCDs and TCD-AgNP nanocomposites were spherical in shape with an average size of 6.3 nm and 11.5 nm respectively. The antibacterial studies proved that TCD-AgNP nanocomposites ware highly effective against Gram-negative (Serratia marcescens, E. coli,and Pseudomonas aeruginosa) microbial organisms. Besides, TCD-AgNP nanocomposite was used as a photocatalyst for the degradation of MB (10 ppm) under sunlight irradiation for regular intervals of time at room temperature with a photodegradation efficiency of 95.63%.

Engineering wafer scale single-crystalline Si growth on epitaxial Gd2O3/Si(111) substrate using radio frequency sputtering for silicon on insulator application

Silicon on Insulator (SOI) technology has been the promising solution for the On-chip low-power mixed-signal systems. However, the traditional smart-cut method for SOI wafer fabrication is costly. Hence, in this work, we present an optimized methodology to fabricate a wafer scale single-crystalline Si on epitaxial Gd2O3/Si(111) substrate (SOXI) using a low-cost, high volume manufacturable (HVM)-friendly Radio Frequency magnetron sputtering technique for SOI application. The grown Si and Gd2O3 layers are physically characterized using high-resolution X-ray Diffraction and high-resolution Transmission Electron Microscopy (HRTEM). The Grazing Incidence X-ray Diffraction, Pole Figure, and HRTEM imaging confirm the formation of an epitaxial Top-Si layer on the epitaxial-Gd2O3/Si(111) substrate. Hence, we demonstrate a low-cost, HVM-friendly technique for the fabrication of SOXI wafers.

Regulated Photocatalytic CO2-to-CH3OH Pathway by Synergetic Dual Active Sites of Interlayer.

Herein, composites of nanosheets with van der Waals contacts are employed to disclose how the interlayer-microenvironment affects the product selectivity of carbon dioxide (CO2) photoreduction. The concept of composites of nanosheets with dual active sites is introduced to manipulate the bonding configuration and promote the thermodynamic formation of methanol (CH3OH). As a prototype, the CoNi2S4-In2O3 composites of nanosheets are prepared, in which high-resolution transmission electron microscopy imaging, X-ray photoelectron spectroscopy spectra, and zeta potential tests confirm the presence of van der Waals contacts rather than chemical bonding between the In2O3 nanosheets and the CoNi2S4 nanosheets within the composite. The fabricated CoNi2S4-In2O3 composites of nanosheets exhibit the detection of the key intermediate *CH3O during CO2 photoreduction through in situ Fourier transform infrared spectra, while the In2O3 nanosheets and CoNi2S4 nanosheets alone do not show this capability, further verified by the density functional theory calculations. Accordingly, the CoNi2S4-In2O3 composites of nanosheets show the ability to produce CH3OH, whereas the CoNi2S4 and In2O3 nanosheets solely generate carbon monoxide products from CO2 photoreduction.

Low-dose electron microscopy imaging for beam-sensitive metal-organic frameworks.

Metal-organic frameworks (MOFs) have garnered significant attention in recent years owing to their exceptional properties. Understanding the intricate relationship between the structure of a material and its properties is crucial for guiding the synthesis and application of these materials. (Scanning) Transmission electron microscopy (S)TEM imaging stands out as a powerful tool for structural characterization at the nanoscale, capable of detailing both periodic and aperiodic local structures. However, the high electron-beam sensitivity of MOFs presents substantial challenges in their structural characterization using (S)TEM. This paper summarizes the latest advancements in low-dose high-resolution (S)TEM imaging technology and its application in MOF material characterization. It covers aspects such as framework structure, defects, and surface and interface analysis, along with the distribution of guest molecules within MOFs. This review also discusses emerging technologies like electron ptychography and outlines several prospective research directions in this field.

Trimetallic alloy nanoparticles as cocatalyst for improving the photocatalytic performance of graphitic carbon nitride for H2 production

Trimetallic alloy nanoparticles (NPs) hybridized with graphitic carbon nitride (g-C3N4) nanosheets show potential as photocatalysts owing to their multicomponent interactions, increased catalytic efficiency, and enhanced stability. Herein, a NiCoAg–CN nanocomposite comprising NiCoAg alloy NPs deposited on g-C3N4 nanosheets was synthesized via photoreduction using simulated solar light. X-ray photoelectron spectroscopy revealed the metallic properties of Ni, Co, and Ag within the NiCoAg–CN nanocomposite, and the high-resolution transmission electron microscopy image showed alloy NPs on the surface of g-C3N4. The as-formed Schottky junction accelerated the separation and transfer of photoinduced charge carriers in NiCoAg–CN. NiCoAg–CN exhibited a remarkable photocatalytic hydrogen (H2) yield of 4896 μmol/g, surpassing the performance of NiAg–CN and CoAg–CN by 1.9- and 1.8-fold, respectively. This is attributed to the enhanced catalytically active sites, facilitating rapid charge carrier transfer between the NiCoAg alloy and the g-C3N4 nanosheets. Photoluminescence spectra indicated that NiCoAg NPs served as efficient electron conduits, suppressing charge carrier recombination and promoting direct electron transfer. Alloy NPs synthesized via the proposed strategy efficiently harness solar radiation, facilitate charge carrier transfer, and mitigate recombination, thus advancing efficient photocatalytic H2 generation.

Emerging 2D nanoscale metal oxide sensor: semiconducting CeO2nano-sheets for enhanced formaldehyde vapor sensing.

Herein, we fabricated nanoscale 2D CeO2sheet structure to develop a stable resistive gas sensor for detection of low concentration (ppm) level formaldehyde vapors. The fabricated CeO2nanosheets (NSs) showed an optical band gap of 3.53 eV and cubic fluorite crystal structure with enriched defect states. The formation of 2D NSs with well crystalline phases is clearly observed from high-resolution transmission electron microscope (HRTEM) images. The NSs have been shown tremendous blue-green emission related to large oxygen defects. A VOC sensing device based on fabricated two-dimensional NSs has been developed for the sensing of different VOCs. The device showed better sensing for formaldehyde compared with other VOCs (2-propanol, methanol, ethanol, and toluene). The response was found to be 4.35, with the response and recovery time of 71 s and 310 s, respectively. The device showed an increment of the recovery time (71 s to 100 s) with the decrement of the formaldehyde ppm (100 ppm to 20 ppm). Theoretical fittings provided the detection limit of formaldehyde ≈8.86 ± 0.45 ppm with sensitivity of 0.56 ± 0.05 ppm-1. The sensor device showed good reproducibility with excellent stability over the study period of 135 d, with a deviation of 1.8% for 100 ppm formaldehyde. The average size of the NSs (≈24 nm) calculated from HRTEM observation showed lower value than the calculated Debye length (≈44 nm) of the charge accumulation during VOCs sensing. Different defect states, interstitial and surface states in the CeO2NSs as observed from the Raman spectrum and emission spectrum are responsible for the formaldehyde sensing. This work offers an insight into 2D semiconductor-based oxide material for highly sensitive and stable formaldehyde sensors.

Boosting green hydrogen production with ZnS@MoS2 2D materials: A structural, electrochemical and photocatalytic analysis

Sustainable green hydrogen production and utilization is one of the serious options to net-zero emission and to mitigate climate change. Herein, a range of techniques has been employed to extricate structural alterations and assess electrochemical (EC) and photocatalytic (PC) properties of MoS2 and ZnS deposited MoS2 (ZnS@MoS2) 2D Materials for green hydrogen production. These 2D materials were explored via a simple hydrothermal method. X-Ray Diffraction (XRD) analysis of ZnS@MoS2 2D materials disclosed significant structural transformations, attributed to ZnS deposition, evident through peak shifts and the emergence of new peaks. Scanning electron microscopy (SEM) images revealed distinct flower-like, petal-arranged formations in MoS2 and ZnS@MoS2, while as high-resolution transmission electron microscopy (HR-TEM) images provided insights into the nanoscale structure and the d‐spacing of MoS2 and ZnS@MoS2 materials. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were utilized to determine elemental composition, chemical states, and structural characteristics. Electrochemical assessments showed that MoS2 exhibited a hydrogen evolution reaction (HER) with an onset potential of −0.3 V, whereas ZnS@MoS2 demonstrated an improved HER with an onset potential of −0.25 V (relative to Ag/AgCl). Notably, the ultra-low overpotential (η@10) of −0.40 V for MoS2 and −0.30 V for ZnS@MoS2, underlined their exceptional catalytic effectiveness. Moreover, ZnS@MoS2 material accomplished an improved photocatalytic hydrogen evolution rate of 4663.5 µmolh−1g−1, surpassing MoS2’s rate of 3318.85 µmolh−1g−1. In conclusion, it is believed that ZnS@MoS2 material can be a potential candidate for green hydrogen production, not only by splitting ultrapure water but future work will explore the catalyst’s performance in seawater electrolysis.

Achieving high sheet resistance and near-zero temperature coefficient of resistance in NiCr film resistors by Al interlayers

Thin film resistive materials with low temperature coefficients of resistance (TCR) and high sheet resistances are essential for various electronic applications, such as embedded resistors. In this study, Al inserting layers and NiCr resistive layers were sequentially deposited on alumina ceramic substrates via DC magnetron sputtering to fabricate Al/NiCr bilayer resistive materials. The electrical properties of the bilayer films were adjusted by varying the thicknesses of the Al inserting layers and annealing conditions. When the thickness of the Al inserting layer varied from 5 to 7.5 nm, and post-annealing treatments ranging from 200℃ to 400℃ were applied, evident Al-NiCr interdiffusion occurred, forming intermediate layers at the interfaces and oxides on the film surfaces. A mixture of partial crystalline phases and amorphous phases was also observed in the cross-sectional high-resolution transmission electron microscope (HRTEM) images. The formation of intermediate layers and surface oxides and the balance between partial crystalline phases and amorphous phases collectively enhanced the electrical performance of bilayer film resistors, achieving thin film resistors with a remarkably low TCR of −6.61 ppm/K and a sheet resistance of up to 265.95 Ω/sq. By rational design of Al layers, NiCr layers and thermal treatment, thin film resistors with near zero TCRs and extremely wide sheet resistance range of 93.34–1439.01 Ω/sq can be obtained.

Tuning Van Der Waals Heterostructure of WS2/SrTiO3 Via in Situ Transmission Electron Microscopy

Monolayer two-dimensional (2D) materials have been widely researched and discussed in recent years, while multi-layers have received comparatively less attention. Nowadays, combining different materials to create heterostructures has become mainstream. In semiconductor industry, heterostructure can form devices such as lasers, light-emitting diodes, fast transistors and so on. Heterostructures can create well electronic properties by combining two different materials together. Therefore, heterostructures become a great tool to manipulate the electronic structures. In traditional heterostructures, the interfaces between two different materials are formed by covalent bonds, hence it requires similar lattice constants and structures. On the other hand, novel van der Waal heterostructures (vdW-heterostructure), formed by 2D materials, do not require the same strict similarity as traditional ones. VdW-heterostructures, which create 3D structures through van der Waals forces, provide a new perspective. In this study, we created a vdW-heterostructures by stacking tungsten disulfide (WS2) with single-crystal strontium titanate, SrTiO3 (STO), shown in Figure 1a,b. The crystalline atomic-layer WS2 and STO were synthesized by chemical vapor deposition (CVD) and pulsed laser deposition (PLD), respectively. They are analyzed by high-resolution transmission electron microscope (HRTEM) shown in Figure 1c-h. Once the vdW-heterostructures are formed, we conducted in situ heating by TEM. Through the advanced in situ technique, we observed the change of the twisted stacking angle by heating the vdW-heterostructure. Ultimately, the lattices will shift and rotate, minimizing the free energy, so that the vdW-heterostructure will be aligned and formed epitaxially. In addition, we utilized atomic resolution scanning transmission electron microscope (STEM) to identify the stacking images and the moiré pattern of the vdW-heterostructure. During the rotation, we can observed different moiré patterns by various twisted stacking angles. These different moiré patterns can produce different electrical properties, which can be applied to advanced semiconductor devices. Keywords: high-resolution TEM/STEM, in situ heating, 2D materials, van der Waal heterostructures, moiré pattern Figure 1. The vdW-heterostructure of STO/WS2. a) The diagram showing that the formation process of WS2/STO vdW-heterostructures which have different twisted stacking angles. b) The low-magnification SEM image showing that the single crystal STO thin film is transferred onto the TEM heating chips. The circles in the middle are the observation windows for transmission electrons. c-e) HRTEM images. f-g) Diffraction patterns of HRTEM. c,f) Single crystal STO thin film with d-spacing (1−10) = 0.284 nm. d,g) Monolayer single crystal WS2 with d-spacing (−110) = 0.274 nm. e,h) WS2(red)/STO(yellow) vdW-heterostructure with stacking angle 3.6°. Figure 1

Deep Learning Assisted High Resolution Microscopy Image Processing for Phase Segmentation in Functional Composite Materials

In the domain of battery research, the processing of high-resolution microscopy images is a challenging task, as it involves dealing with complex images and requires a prior understanding of the components involved. The utilization of deep learning methodologies for image analysis has attracted considerable interest in recent years, with multiple investigations employing such techniques for image segmentation and analysis within the realm of battery research. However, the automated analysis of high-resolution microscopy images for detecting phases and components in composite materials is still an underexplored area.The presentation discusses the formulation of a sophisticated deep learning-assisted workflow tailored for the meticulous processing of high throughput, high-resolution microscopy images to detect, map and analyze the evolution of periodic components from a stack of high-resolution Transmission Electron Microscopy (TEM) image. The developed methodology employs deep learning techniques and utilizes Fast Fourier Transform (FFT) patterns extracted from TEM images to analyze feature positions and ascertain periodic components. The approach incorporates innovative strategies to process high-resolution images, capitalizing on the symmetry within FFT patterns to enhance model performance. This methodology streamlines the detection and mapping of components while the intensity profiles derived from the frames provide valuable insights into the evolution of periodic components within the sample during the imaging period.High-resolution images obtained through a beam damage analysis investigation of lithium fluoride (LiF), a prevalent constituent within the solid-electrolyte interphase (SEI) of cycled lithium metal anodes, were employed to assess the program's scalability and robustness. The study elucidated decomposition products and their spatial distribution. Furthermore, the intensity profile of periodic components detected across multiple frames aided in evaluating the beam damage mechanism of the LiF component.Our research has resulted in an open-source Python GUI program that the research community can freely access and experiment with. Figure 1

In Situ transmission Electron Microscope Observation of Biased-Induced Dynamic Evolution of Two-Dimensional CrS2

Two-Dimensional transition-metal dichalcogenides (2D-TMDs) have attracted great attention recently owing to their potential to become the important material for next generation semiconductor devices. While using the device, it needs to ensure high density current and biased voltage for a long time. However, the study on TMDs in high-energy environment is insufficient. In this work, the phase evolution of CrS2 are revealed via in-situ biasing experiments and recorded by transmission electron microscope (TEM) at atomic scale. The ultra-thin layered (~1.6nm) CrS2 was synthesized through atmospheric pressure chemical vapor deposition (APCVD), followed by transferring the as-grown samples onto specialized TEM electrical chips. The TEM characterization of CrS2 initial sample provided the basic understanding of this Cr-based TMD, identified as pure 1T phase with single crystal structure as shown in Figure 1. The advanced in situ technique was employed to record the structural evolution and was tested the endurance of CrS2 during biasing. Moreover, the results can make significant contributions to future semiconductor device designs and demonstrate CrS2 has great potential as a semiconductor device with its outstanding characteristic of biased-endurance. Figure1. (a) Low-magnification TEM image of 1T-CrS2. (b) High-resolution TEM image of 1T-CrS2, corresponding with FFT along [001] zone axis. (c) AFM image of the as-grown CrS2 sample, blue bar in the image is X axis of (d). (d) AFM height profile of as-grown 1T-CrS2 with average thickness of~1.6nm. (e) STEM image of 1T-CrS2 and shows d-spacing~0.336 nm. (f) Low-magnification TEM image of the device, showing that the transferred CrS2 layer was suspended on the membrane with Au electrodes on both sides. (g,h) In-situ TEM observation of the biasing experiment after 5V biasing for 5 min of 1T-CrS2. Time-sequencing TEM images showing the structural evolution of biasing. The inset shows the corresponding FFT-DP to reveal the variation of crystallinity of the sample. (g) Initial structure of 1T-CrS2. (h) 1T-CrS2 under in-situ biasing experiment after 10 minutes. Figure 1