Diffraction Transmission Electron Research Articles

Investigation of the structural stability of polycrystalline cBN under near-industrial grinding process conditions

Cubic boron nitride (cBN) is an important material in the cutting and metal processing industries due to its exceptional hardness and high thermal stability, which allows it to withstand temperatures up to 1400 °C without decomposing. These properties make cBN and, with that, polycrystalline cBN (PcBN) ideal materials for high-speed machining and other applications, resulting in increased efficiency and reduced costs in production processes. Despite its established importance, the possibility of phase transformations into hexagonal boron nitride phases or partial amorphization during industrial PcBN grinding processes remains unclear and, due to the deteriorated mechanical characteristics, raised recently some concerns about possible losses of cBN's hardness, wear resistance, and abrasive properties. In order to address this issue and for identifying such potential structural changes, a commercial PcBN grade was exposed to near-industrial grinding process conditions and then characterized in detail by conventional (scanning) transmission electron microscopy (S)TEM and (scanning) electron diffraction techniques. To understand the influence of the PcBN machining on the material, the grinding process also needs to be assessed via the identification of chip formation mechanisms, which is as well addressed in this work. The main outcome of this study, combining a material analysis and a manufacturing technology point of view, is that there is so far no evidence of any structural instabilities of PcBN under usual processing conditions.

Spherical and porous Cu2O nanocages with Cu2O/Cu(OH)2 Surface: Synthesis and their promising selectivity for catalysing CO2 electroreduction to C2H4

In the production of C2H4, a vital raw material in the synthesis of polyethylene and polyvinyl chloride, Cu2O is a highly promising catalyst with excellent Faradaic efficiency and selectivity. We propose a method involving the partial reduction of Cu(OH)2 to Cu2O by sodium L-ascorbate for the synthesis of spherical and porous Cu2O nanocages (SPNCs) with a surface containing both Cu2O and Cu(OH)2. High-resolution transmission electron microscopy and electron diffraction measurements revealed ∼ 3-nm pores and a (13¯2) high-index facet on the SPNC, respectively. As SPNCs have a porous structure, their specific surface area is greater (31.10 m2 g−1) than that (6.35 m2 g−1) of spherical Cu2O nanocrystals (SNCs) with solid interiors. Furthermore, SPNCs, when applied as electrocatalysts for catalysing the CO2 reduction reaction (CO2RR), demonstrated remarkable mass activities (16.92 mA mg−1 at −1.15 V vs. reversible hydrogen electrode) for C2H4 production, with a Faraday efficiency reaching an impressive 55.3 %. Stability test data showed a consistent CO2RR current density over 6 h, owing to the porous structure and the presence of both Cu(OH)2 and Cu2O on the catalyst surface. Our proposed SPNC catalysts can be employed as effective CO2RR catalysts for producing C2H4, which may help in reducing the present reliance on petrochemical processes.

Revisiting the Crystallography of {225}γ Martensite: How EBSD Can Help to Solve Long-Standing Controversy

Explaining the crystallography of iron alloys martensite with a {225}γ habit plane remains a challenging task within the phenomenological theory of martensite crystallography. The purpose of this study is to re-examine the martensite formed in a Fe-8Cr-1.1C alloy using EBSD, which has a better angular resolution than the conventional transmission electron diffraction techniques previously used. The results show that the single morphological plates, which hold a near {225}γ habit plane, are bivariant composites made up of two twin-related variants. It is shown that a {113}γ plane is systematically parallel to one of the three common 112α planes between the two twin-related crystals. This observation suggests that the lattice invariant strain of transformation occurs through a dislocation glide on the {113}γ ⟨110⟩γ system, rather than through twinning as is commonly accepted. Based on this assumption, the predictions of Bowles and Mackenzie’s original theory are in good agreement with the crystallographic features of {225}γ martensite. Unexpectedly, it is the high shear solution of the theory that gives the most accurate experimental predictions.

Crystallography and Interface Structures in As-Arc Melted and Laser Surface-Remelted Aluminum–Silicon Alloys with and without Strontium Addition

The crystallography of the eutectic Al-Si microstructure in both unmodified and Sr (0.2 wt.%)-modified hypereutectic Al-20 wt.% Si alloys, processed via arc-melting and laser surface remelting, has been comprehensively characterized using transmission electron microscopy and electron diffraction. Although, under as-cast conditions, specific orientations between different planes of Al and Si, satisfying defined orientation relationships (ORs), have been investigated within the flake morphology, the rapid solidification induced by laser surface remelting results in a notable transformation from a flake morphology to nanocrystalline Si fibers dispersed in an Al matrix. Consequently, this transformation results in a mis-orientation of the interface between the eutectic Al and Si phases, preventing the formation of orientation relationships, thus promoting the formation of faceted interfaces exhibiting substantial lattice disregistry.

Impact of palladium/palladium hydride conversion on electrochemical CO2 reduction via in-situ transmission electron microscopy and diffraction

Electrochemical conversion of CO2 offers a sustainable route for producing fuels and chemicals. Pd-based catalysts are effective for converting CO2 into formate at low overpotentials and CO/H2 at high overpotentials, while undergoing poorly understood morphology and phase structure transformations under reaction conditions that impact performance. Herein, in-situ liquid-phase transmission electron microscopy and select area diffraction measurements are applied to track the morphology and Pd/PdHx phase interconversion under reaction conditions as a function of electrode potential. These studies identify the degradation mechanisms, including poisoning and physical structure changes, occurring in PdHx/Pd electrodes. Constant potential density functional theory calculations are used to probe the reaction mechanisms occurring on the PdHx structures observed under reaction conditions. Microkinetic modeling reveals that the intercalation of *H into Pd is essential for formate production. However, the change in electrochemical CO2 conversion selectivity away from formate and towards CO/H2 at increasing overpotentials is due to electrode potential dependent changes in the reaction energetics and not a consequence of morphology or phase structure changes.

On-Chip Modification of Titanium Electrothermal Characteristics by Joule Heating: Application to Terahertz Microbolometer.

This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance ~14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of -0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiOx) semiconducting phase on the Ti phase (~85% purity) deposited initially, further to the heating. Formation of TiOx during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity.

Facile Synthesis of Stable Nanosized Silver Clusters in Plasma Discharge Under Ultrasonic Cavitation

This work is devoted to the study of plasma-chemical processes determined by the combination of the effect of thermally nonequilibrium, low-temperature plasma and intensive ultrasonic vibrations in the regime of intensive cavitation on liquid-phase media. This method for the realization of plasma-chemical transformations has been proven to be of significant interest and to have advantages for the creation of new nano-sized materials with special properties because it allows for varying the electrophysical and acoustic characteristics of the process when carrying out plasma-chemical reactions and fusion reactions. In this work, a novel facile technique for the synthesis of nanosized silver clusters in plasma discharge under ultrasonic cavitation is reported. Such a type of plasma involves the simultaneous effect of high-intensity cavitation and steady electric discharge in a liquid phase between electrodes of desired material. As a result, stable tiny silver nanoclusters with around a 1-nm size and a relatively narrow particle size distribution were obtained using toluene as a liquid medium. The nanoclusters were characterized with dynamic light scattering, transmission electron microscopy, electron diffraction, and optical methods. The results confirmed the formation of nanoclusters with an absorbance peak around 300 nm and the absence of 400-nm peaks typical for silver nanoparticles. Fluorescence tests allowed for establishing the amorphous structure of the synthesized nanoclusters occupying the intermediate position between few-atom nanoclusters and nanoparticles. The nanoclusters obtained were proven to be stable for more than 3 months. The experiments also revealed the possibility of performing high-temperature plasma-chemical reactions that can be applied in fusion technology.

Preparation, characterization and mechanical properties analysis of SAC305-SnBi-Co hybrid solder joints for package-on-package technology

The development of hybrid solder for chip packing is a major 3D packaging research topic. The incorporation of with low melting points into solder materials has been used in low-temperature packaging. Hybrid solder struggles to enhance low-temperature solder efficiency and mechanical properties. This work examined the effects of Co elements on microstructure and intermetallic compound (IMC) morphology of SAC305-SnBi-Co hybrid solder generated by reflow welding on electroless nickel immersion gold (ENIG) substrate at various temperatures. Moreover, mechanical characteristics and failure behavior of joints were extensively explored. The results show that the addition of 0.05% Co reduced the melting range of the solder and improved the wettability of SnBi solder. According to transmission electron microscopes (TEM) and electron diffraction spots (EDS), the crystal structure of the grains is (Cu, Co)6Sn5 basic-centered monoclinic crystal. Fourier analysis of high-resolution images yields deformed lattice fringes, indicating that Co atoms fill Cu6Sn5's lattice gap in IMC. The shear strength of SAC305/SnBi hybrid solder joints with Co rises and then decreases with temperature. The highest shear strength of solder joints with 0.05% Co (40 nm) is 73.2 MPa at 220 °C, whereas joints with 0.1%Co are 67.5 MPa. Combined with the fracture morphology, the proportion of IMC fracture mode decreased after adding Co element.

Analysis of contact zone of coating-substrate system exposed to irradiation with a pulse electron beam

Using the wire-arc additive manufacturing method (WAAM) on a 5083 aluminum alloy substrate, a non-equiatomic Mn – Cr – Fe – Co – Ni high-entropy alloy (HEA) coating was formed. By scanning and transmission electron diffraction microscopy we analyzed the structure, phase and elemental composition of the contact zone after irradiation with high-current low-energy electron beams with the following parameters: accelerated electron energy 18 keV, electron beam energy density 30 J/cm2, electron beam pulse duration 200 µs, number of pulses 3, pulse repetition rate 0.3 s–1. Multiphase multielement submicro- and nanocrystalline structures are formed predominantly in the substrate, which has a lower melting temperature compared to HEAs. Mutual doping of the coating – substrate system occurs in the contact layer, which has sinuous boundaries. The contact layers adjacent to the substrate and coating have the structure of high-speed cellular crystallization. In the layer adjacent to the substrate, the cells are formed by a solid solution of magnesium in aluminum. Interlayers of the second phase, enriched in atoms of the coating and substrate, are revealed along the cell boundaries. In the layer adjacent to the coating, the cells are formed by an alloy of composition 0.17Mg – 20.3Al – 4.3Cr – 16.7Fe – 9.3Co – 49.2Ni corresponding to the coating. Interlayers of the second phase, enriched mainly in magnesium and, to a lesser extent, in atoms of the HEA coating, are located along the cell boundaries. Central region of the contact zone with a thickness of ~1700 μm is formed by lamellar crystallites, which indicates the eutectic nature of its formation. Its main element is aluminum (≈77 at. %).

Atomic-scale probing of short-range order and its impact on electrochemical properties in cation-disordered oxide cathodes

Chemical short-range-order has been widely noticed to dictate the electrochemical properties of Li-excess cation-disordered rocksalt oxides, a class of cathode based on earth abundant elements for next-generation high-energy-density batteries. Existence of short-range-order is normally evidenced by a diffused intensity pattern in reciprocal space, however, derivation of local atomic arrangements of short-range-order in real space is hardly possible. Here, by a combination of aberration-corrected scanning transmission electron microscopy, electron diffraction, and cluster-expansion Monte Carlo simulations, we reveal the short-range-order is a convolution of three basic types: tetrahedron, octahedron, and cube. We discover that short-range-order directly correlates with Li percolation channels, which correspondingly affects Li transport behavior. We further demonstrate that short-range-order can be effectively manipulated by anion doping or post-synthesis thermal treatment, creating new avenues for tailoring the electrochemical properties. Our results provide fundamental insights for decoding the complex relationship between local chemical ordering and properties of crystalline compounds.

Thermokinetic Study of Aluminum-Induced Crystallization of a-Si: The Effect of Al Layer Thickness.

The effect of the aluminum layer on the kinetics and mechanism of aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in (Al/a-Si)n multilayered films was studied using a complex of in situ methods (simultaneous thermal analysis, transmission electron microscopy, electron diffraction, and four-point probe resistance measurement) and ex situ methods (X-ray diffraction and optical microscopy). An increase in the thickness of the aluminum layer from 10 to 80 nm was found to result in a decrease in the value of the apparent activation energy Ea of silicon crystallization from 137 to 117 kJ/mol (as estimated by the Kissinger method) as well as an increase in the crystallization heat from 12.3 to 16.0 kJ/(mol Si). The detailed kinetic analysis showed that the change in the thickness of an individual Al layer could lead to a qualitative change in the mechanism of aluminum-induced silicon crystallization: with the thickness of Al ≤ 20 nm. The process followed two parallel routes described by the n-th order reaction equation with autocatalysis (Cn-X) and the Avrami-Erofeev equation (An): with an increase in the thickness of Al ≥ 40 nm, the process occurred in two consecutive steps. The first one can be described by the n-th order reaction equation with autocatalysis (Cn-X), and the second one can be described by the n-th order reaction equation (Fn). The change in the mechanism of amorphous silicon crystallization was assumed to be due to the influence of the degree of Al defects at the initial state on the kinetics of the crystallization process.

Martensitic transformation pathways and crystallographic orientation relationships in steel

Martensite is one of the most important structures determining the ability to tailor the performance of steel and several other engineering materials. In previous studies, the face-centered cubic (FCC) to hexagonal close-packed (HCP) (or body-centered cubic (BCC)) martensitic transformation and the FCC to body-centered tetragonal (BCT) (or BCC) martensitic transformation during deformation and quenching were widely investigated; these transformations usually improve the plasticity and strength of steel, respectively. In this work, detailed transmission electron microscopy (TEM) observations and electron diffraction pattern analyses of the BCT and BCC twins are performed along the [110], [131], and [1¯53] zone axes. The transformation of BCT twins into BCC twins along the [131] zone axis is also analyzed through in situ heating during the TEM observations. The high-resolution TEM observations of mutually perpendicular BCT variants are consistent with the atomic arrangement obtained for the quenching pathway during the martensitic transformation. In addition, different orientation relationships between austenite and martensite are explained in terms of the atomic migration occurring during the deformation pathway and the quenching pathway of the martensitic transformation.

Nanocomposite Didymium-Fe-B/Alnico magnetic alloys with core shell structure and improved magnetic properties

NdFeB-based permanent magnets have the highest maximum energy products, but their low Curie temperatures limit their applications. Alnico permanent magnets have relatively modest magnetic energy products, but have very high Curie and working temperatures. In this manuscript, we report new NdPrFeB/Alnico nanocomposite magnetic materials with enhanced Curie temperatures and maximum magnetic energy products. A special microstructure with the Alnico phase dispersed within the NdPrFeB phase results in excellent magnetic properties. The Curie temperature of the composite alloys is enhanced from 570 K to 643 K by adding 25% low-grade Alnico. The enhanced Curie temperature which results from the cobalt and nickel replacement for iron in the 2:14:1 phase, and the molecular field penetration improves the temperature stability of the magnets. The beneficial heterogeneous distribution of the constituent phases and elements was confirmed by transmission electron microscopy and electron diffraction spectroscopy analyses. The maximum energy product is enhanced from 110 kJ/m3 to 133 kJ/m3. Magnetostatic interaction and exchange interaction in the alloys were studied by means of Henkel plots and minor hysteresis loop measurements. Despite the high content of the Alnico phase with relatively large special dimensions, there were no kinks in the demagnetization curves either at 300 K or 400 K. Furthermore, no kink was noted at low and high applied fields in the demagnetization-magnetization process which shows the effective magnetic interactions. This work would elucidate the development of nanocomposite magnetic material with high energy product without the use of heavy rare earths and with the economical use of Nd and Pr.

Determination of the percentage of magnetite in iron oxide nanoparticles: A comparison between mössbauer spectroscopy and Raman spectroscopy

Nanomaterials and especially iron oxide nanoparticles become more common for several fields such as data storage or biomedical applications. For these biomedical applications, iron oxide nanoparticles with a superparamagnetic state are the most used as cancer treatment, contrast agent for MRI … To obtain a superparamagnetic state, the iron oxide must be less than 20 nm in size. It exists several types of iron oxide with a superparamagnetic behaviour: magnetite (Fe3O4) and maghemite (γ-Fe2O3). For the biomedical fields, the magnetic behaviour must be maximal, therefore the iron oxide synthesised in a preferential way is magnetite. A microwave process is carried out because this synthesis allows to obtain monodisperse nanoparticles with a narrow size distribution and a good crystallinity. However, the quantity of magnetite in our samples is not known exactly. The goal of this study is to determine the amount of magnetite in our samples. The most accurate technique to determine the proportion of magnetite is Mössbauer spectroscopy. A study of our samples with this technique is carried out and is compared to another technique which is Raman spectroscopy. In this work, iron oxide nanoparticles synthesised with a microwave process are characterized by Transmission Electronic Microscopy, X-Ray Diffraction, magnetic measurements, Mössbauer spectroscopy and Raman spectroscopy.

Structural and optical properties of Zn-implanted silica: effect of fluence and annealing

The phase-structural composition of silica films grown on Si substrates implanted with different fluences of Zn ions has been studied using transmission electron microscopy (TEM) and electron diffraction. Small clusters (2–3 nm) and larger clusters (5–7 nm) were formed in the as-implanted silica films with Zn concentration of 6–8 at % and 16%–18%, respectively. Furnace annealing at 750 °С for two hours in air resulted in the formation of an orthorhombic Zn2SiO4 phase (space group R-3) in the case of low fluence (5 × 1016 cm−2) and in the formation of a zinc blended ZnO phase (space group F-43m) in the case of high fluence (1 × 1017 cm−2). Based on the Rutherford backscattering spectrometry (RBS) data, it has been shown that impurity losses during implantation and subsequent annealing increase with the fluence of the implanted ions. The photoluminescence data were consistent with the TEM and RBS.

Effects of annealing in vacuum on the microstructure of silicon-containing calcium phosphate films deposited on a ZrNb alloy by radio-frequency magnetron sputtering

Coatings were deposited on the surface of a ZrNb alloy by radio-frequency magnetron sputtering using targets consisting of either pure crystalline hydroxyapatite (HA) or silicon-containing HA (Si-HA). The coated ZrNb samples were heated in a vacuum furnace at a pressure of 5 × 10−5 Torr and temperature 700 °C for 2 h. Precursor powders of silicate-substituted HA [Ca10(PO4)6−x(SiO4)x(OH)2−x, x = 0, 0.5, or 1.72] were used to fabricate the targets for sputtering. The aim of this study was to analyze the effect of Si addition to HA on crystallization behavior and structure of the resulting films using transmission electron microscopy and electron diffraction patterns of selected sites. The average thickness of the films was in the range of 175–345 nm. The Si substitution in HA played a major role in the mechanisms of coating formation and crystallization behavior, which influenced the structure and crystallinity of the layers deposited by radio-frequency magnetron sputtering. Moreover, the results indicate that surface-induced crystallization of the deposited thin films is more pronounced than internal crystallization. A possible mechanism underlying the observed decrease in the crystallization rate with the increasing silicate content in the HA-based films is discussed.

Successful Growth of TiO2 Nanocrystals with {001} Facets for Solar Cells

The growth of nanocrystals (NCs) from metal oxide-based substrates with exposed high-energy facets is of particular importance for many important applications, such as solar cells as photoanodes due to the high reactivity of these facets. The hydrothermal method remains a current trend for the synthesis of metal oxide nanostructures in general and titanium dioxide (TiO2) in particular since the calcination of the resulting powder after the completion of the hydrothermal method no longer requires a high temperature. This work aims to use a rapid hydrothermal method to synthesize numerous TiO2-NCs, namely, TiO2 nanosheets (TiO2-NSs), TiO2 nanorods (TiO2-NRs), and nanoparticles (TiO2-NPs). In these ideas, a simple non-aqueous one-pot solvothermal method was employed to prepare TiO2-NSs using tetrabutyl titanate Ti(OBu)4 as a precursor and hydrofluoric acid (HF) as a morphology control agent. Ti(OBu)4 alone was subjected to alcoholysis in ethanol, yielding only pure nanoparticles (TiO2-NPs). Subsequently, in this work, the hazardous chemical HF was replaced by sodium fluoride (NaF) as a means of controlling morphology to produce TiO2-NRs. The latter method was required for the growth of high purity brookite TiO2 NRs structure, the most difficult TiO2 polymorph to synthesize. The fabricated components are then morphologically evaluated using equipment, such as transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron diffraction (SAED), and X-ray diffraction (XRD). In the results, the TEM image of the developed NCs shows the presence of TiO2-NSs with an average side length of about 20-30 nm and a thickness of 5-7 nm. In addition, the image TEM shows TiO2-NRs with diameters between 10 and 20 nm and lengths between 80 and 100 nm, together with crystals of smaller size. The phase of the crystals is good, confirmed by XRD. The anatase structure, typical of TiO2-NS and TiO2-NPs, and the high-purity brookite-TiO2-NRs structure, were evident in the produced nanocrystals, according to XRD. SAED patterns confirm that the synthesis of high quality single crystalline TiO2-NSs and TiO2-NRs with the exposed {001} facets are the exposed facets, which have the upper and lower dominant facets, high reactivity, high surface energy, and high surface area. TiO2-NSs and TiO2-NRs could be grown, corresponding to about 80% and 85% of the {001} outer surface area in the nanocrystal, respectively.

Treatment of Fly-Ash-Contaminated Wastewater Loaded with Heavy Metals by Using Fly-Ash-Synthesized Iron Oxide Nanoparticles

Every year, a huge amount of water is polluted by various sources, out of which coal fly ash (CFA) is one of the major pollutants. CFA has a large number of toxic metals, which reaches water bodies by coming in contact with water or rain. Due to heavy-metal contamination, water becomes unfit for drinking for human beings, which in long term may cause several disorders. Thus, iron oxide nanoparticles (IONPs) recovered from waste, such as CFA, could be the most promising material for treating wastewater, due to their low-cost, recyclable nature and magnetic property. The synthesis of IONPs from CFA involves three sequential steps. The first step involves extraction of ferrous materials from CFA, followed by acidic treatment of ferrous materials to obtain acidic leachate, and lastly the precipitation of iron oxides by an alkali. The particle size of the synthesized IONPs varied from 30–70 nm and purity was about 90–93%, as confirmed by transmission electron microscope (TEM) and electron diffraction spectroscopy (EDS). Further, the synthesized IONPs were used for the remediation of various heavy metals, especially Pb and Cr ions from 20% CFA aqueous solutions. The heavy-metal removal efficiency of IONPs varied from 40–70%. The developed method suggests heavy-metal removal from wastewater by using an economical and greener route.

Nanostructured nickel films by supersonic cluster beam deposition: Morphology, oxidation, and clues of hollow structures by Kirkendall effect at room temperature

Supersonic Cluster Beam Deposition was exploited to study morphology, nanostructure and room temperature spontaneous oxidation of Nickel films obtained by cluster assembling in high-vacuum conditions. Size analysis shows the dominant presence of particles with dimensions below 10 nm, while the lognormal profile of the size distribution confirms that gas-phase homogeneous nucleation and aggregation prior to deposition is at the base of the mechanism governing clusters formation. The relationship between surface roughness and film thickness is found to follow a power law, suggesting a growth process ascribable to ballistic deposition model. Although ultrafine dimensions, clusters oxidation is not complete as residual metallic Nickel, beside NiO and Ni(OH)2, is detected by Electron Spectroscopy and observed by Transmission Electron Microscopy and Electron Diffraction, within core-shell structures. Cubic symmetry is identified in both metallic and NiO phases, while hydroxide phase appears as amorphous. The presence of hollow particles is also unveiled, which may represent a first clue of room temperature Kirkendall effect in ultrafine Nickel particles produced by Supersonic Cluster Beam Deposition. The coexistence of core-shell and hollow structures of the same size suggests that particle dimension per-se is not enough to define unambiguously the outcomes of room temperature oxidation process.

MoxWx–1S2 Nanotubes for Advanced Field Emission Application

AbstractTransition metal dichalcogenide (TMDC) nanotubes complement the field of low‐dimensional materials with their quasi‐1D morphology and a wide set of intriguing properties. By introducing different transition metals into the crystal structure, their properties can be tailored for specific purpose and applications. Herein, the characterization and a subsequent preparation of single‐nanotube field emission devices of MoxWx‐1S2 nanotubes prepared via the chemical vapor transport reaction is presented. Energy‐dispersive X‐ray spectroscopy, Raman spectroscopy, and X‐ray diffraction  indicate that the molybdenum and tungsten atoms are randomly distributed within the crystal structure and that the material is highly crystalline. High resolution transmission electron microscopy  and electron diffraction (ED) patterns further corroborate these findings. A detailed analysis of the ED patterns from an eight‐layer nanotube reveal that the nanotubes grow in the 2H structure, with each shell consists of one bilayer. The work function of the nanotubes is comparable to that of pure MoS2 and lower of pure WS2 NTs, making them ideal candidates for field emission applications. Two devices with different geometrical setup are prepared and tested as field emitters, showing promising results for single nanotube field emission applications.