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Using advanced in situ transmission electron microscopy, the lithiation and delithiation processes into graphene sheets are studied and significant differences are detected in the structural evolution of the system. Thin fcc lithium crystals with faceted shapes are formed between graphene sheets during lithiation, but are transformed into irregular patches during delithiation. It is found that defects such as vacancies in graphene and impurity atoms play the key role in these processes. Specifically, during intercalation the lithium crystals nucleate at vacancies in graphene, while upon delithiation the impurity oxygen atoms initially embedded at octahedral interstitial positions inside the lithium crystals agglomerate at the edges of the crystals, thus giving rise to the formation of amorphous lithium oxide patches, where lithium ions are trapped. [ABSTRACT FROM AUTHOR]

One of the physical methods for obtaining magnetite nanoparticles (NPs) is electron beam physical vapor deposition (EB PVD), which requires complex equipment, but allows obtaining a significant amount of pure (ligand-free) NPs. The biomedical application of such NPs is less studied than materials from other synthesis methods. The objective is to study the effect of pure magnetite NPs in the NaCl matrix obtained by EB PVD on hematological indicators, gases, electrolytes and parameters of iron metabolism in the blood of intact animals. The physical characteristics of NPs were studied using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, electron energy-loss spectroscopy, selected area electron diffraction and fast Fourier transform. In vivo experiments were conducted on albino male rats, which were injected with solution of magnetite-sodium chloride NPs (1.35 mg Fe/kg). After 3 and 72 h, hematological parameters, blood gases, electrolytes, and serum iron were determined. The synthesized NPs had an average size of 11 nm. They were identified as magnetite, where polycrystals and single crystals were present. The absence of contamination in crystal boundaries, clear orientation and orderliness of atoms in crystals were established. The administration of NPs in the sodium chloride matrix to animals was characterized by a transient increase in the main indicators of red blood accompanied by an increase in the saturation of erythrocytes with hemoglobin and their mean volume after 3 h. It did not worsen blood gases and pH, but decreased blood Na+ content after 72 h. The investigated NPs caused changes in the parameters of serum iron characteristic to iron preparations, which after 3 h were smaller compared to the reference iron drug, and after 72 h—similar to it. More intense rapid effects on hematological parameters at lower serum iron indicate greater activity of the studied pure magnetite NPs obtained by EB PVD syntesis compared to the reference iron preparation. Highlights: Pure magnetite nanoparticles in the NaCl matrix were obtained by EB PVD. They were studied using high-resolution transmission electron microscopy. These nanoparticles had a size of 11 nm, clear orientation and orderliness of atoms in crystals. In healthy animals, they caused a transient increase in red blood indicators. They did not worsen blood gases and pH, but decreased Na+ content in the blood. The nanoparticles caused changes in the serum iron typical to iron preparations. These changes were not toxic and lasting due to compensatory reactions. [ABSTRACT FROM AUTHOR]

High‐resolution transmission electron microscopy (HRTEM) images can capture the atomic‐resolution details of the dynamically changing structure of nanomaterials. Here, we propose a new scheme and an improved reconstruction algorithm to reconstruct the exit wave function for each image in a focal series of HRTEM images to reveal structural changes. In this scheme, the wave reconstructed from the focal series of images is treated as the initial wave in the reconstruction process for each HRTEM image. Additionally, to suppress noise at the frequencies where the signal is weak due to the modulation of the lens transfer function, a weight factor is introduced in the improved reconstruction algorithm. The advantages of the new scheme and algorithms are validated by using the HRTEM images of a natural specimen and a single‐layer molybdenum disulphide. This algorithm enables image resolution enhancement and lens aberration removal, while potentially allowing the visualisation of the structural evolution of nanostructures. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) possesses excellent physical and electrical properties, rendering it particularly suitable for optoelectronic and high-speed electronic applications and thus making it a potentially significant material in integrated circuit technology. Integrating InP on a substrate with high thermal conductivity, such as silicon carbide (SiC), presents a promising solution to mitigate thermal accumulation in InP-based devices. In this study, a hydrophilic bonding process was employed to achieve direct wafer bonding of InP/SiC at room temperature (RT), resulting in an average bonding strength of 3.2 MPa and a thermal conductivity of 112.60 W m–1 K–1 at RT. The interface structure (thinned to 50 nm) was analyzed using high-resolution transmission electron microscopy (HRTEM), revealing close contact at the InP/SiC bonding interface at RT. Nanoscale component diffusion (1.8 nm) at the interface was found to enhance bonding strength. Annealing treatments at 300 and 600 °C were performed to thoroughly investigate nanoscale component diffusion and recombination at the InP/SiO2 interface. The results demonstrated component diffusion at RT with a depth of 2.63 nm. At 300 °C annealing, recrystallization of InP/SiO2 interface components led to the formation of indium oxide (In2O3) with a crystallization depth of 3.89 nm. At 600 °C, annealing caused further recrystallization, producing indium phosphate (InPO4) with a crystallization depth of 5.50 nm. These results were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Nanoscale structural analysis of the InP/SiO2 interface helps to further understand the mechanisms at heterointerfaces and improve the quality of integrated devices. Additionally, simulations calculated the effects of recrystallization products on the optical field mode and transmission loss of the InP waveguide, providing crucial design guidance for InP optoelectronic integration. [ABSTRACT FROM AUTHOR]

Abstract One of the physical methods for obtaining magnetite nanoparticles (NPs) is electron beam physical vapor deposition (EB PVD), which requires complex equipment, but allows obtaining a significant amount of pure (ligand-free) NPs. The biomedical application of such NPs is less studied than materials from other synthesis methods. The objective is to study the effect of pure magnetite NPs in the NaCl matrix obtained by EB PVD on hematological indicators, gases, electrolytes and parameters of iron metabolism in the blood of intact animals. The physical characteristics of NPs were studied using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, electron energy-loss spectroscopy, selected area electron diffraction and fast Fourier transform. In vivo experiments were conducted on albino male rats, which were injected with solution of magnetite-sodium chloride NPs (1.35 mg Fe/kg). After 3 and 72 h, hematological parameters, blood gases, electrolytes, and serum iron were determined. The synthesized NPs had an average size of 11 nm. They were identified as magnetite, where polycrystals and single crystals were present. The absence of contamination in crystal boundaries, clear orientation and orderliness of atoms in crystals were established. The administration of NPs in the sodium chloride matrix to animals was characterized by a transient increase in the main indicators of red blood accompanied by an increase in the saturation of erythrocytes with hemoglobin and their mean volume after 3 h. It did not worsen blood gases and pH, but decreased blood Na+ content after 72 h. The investigated NPs caused changes in the parameters of serum iron characteristic to iron preparations, which after 3 h were smaller compared to the reference iron drug, and after 72 h—similar to it. More intense rapid effects on hematological parameters at lower serum iron indicate greater activity of the studied pure magnetite NPs obtained by EB PVD syntesis compared to the reference iron preparation.

It remains controversial as to whether a face-centered cubic (FCC) phase exists in pure titanium (Ti) upon deformation, since the FCC structures in deformed Ti may well be TiHx resulting from the sample preparation process. Here, by using in situ transmission electron microscopy (TEM), we uncover direct evidences on the nucleation and growth of FCC-Ti right in front of the crack tip in the α-Ti matrix. Atomic resolution images further reveal that the transformation can be mediated by either partial dislocations on basal planes or shear and atomic shuffle on the FCC1 1 0|HCP1 0 -1 0 interfaces.

This study investigates the plastic deformation-induced fcc → hcp → bcc phase transition within nanograins in an ultra-strong gradient nanostructured surface layer on Fe45Mn35Cr10Co10 compositionally complex alloy (CCA), subjected to a single point cubic boron nitride turning process. High-resolution transmission electron microscope observations reveal a novel atomic movement mechanism of this transition following a unique Nishiyama-Wassermann orientation relationship. Unlike the previously validated Bogers-Burgers-Olson-Cohen model, which follows different orientation relationships and relies on two shear components, this study demonstrates that the phase transition in this CCA is cooperatively completed by two sets of half-partial dislocation dipoles and associated atom shuffling.Statement of NoveltyA novel atomic mechanism of fcc → hcp → bcc phase transition, cooperatively completed by two sets of partial dislocation dipoles and atomic shuffling, provides potential implications for advanced structural materials.

This study investigates the plastic deformation-induced fcc → hcp → bcc phase transition within nanograins in an ultra-strong gradient nanostructured surface layer on Fe45Mn35Cr10Co10 compositionally complex alloy (CCA), subjected to a single point cubic boron nitride turning process. High-resolution transmission electron microscope observations reveal a novel atomic movement mechanism of this transition following a unique Nishiyama-Wassermann orientation relationship. Unlike the previously validated Bogers-Burgers-Olson-Cohen model, which follows different orientation relationships and relies on two shear components, this study demonstrates that the phase transition in this CCA is cooperatively completed by two sets of half-partial dislocation dipoles and associated atom shuffling. Statement of Novelty A novel atomic mechanism of fcc → hcp → bcc phase transition, cooperatively completed by two sets of partial dislocation dipoles and atomic shuffling, provides potential implications for advanced structural materials. [ABSTRACT FROM AUTHOR]

It remains controversial as to whether a face-centered cubic (FCC) phase exists in pure titanium (Ti) upon deformation, since the FCC structures in deformed Ti may well be TiHx resulting from the sample preparation process. Here, by using in situ transmission electron microscopy (TEM), we uncover direct evidences on the nucleation and growth of FCC-Ti right in front of the crack tip in the α-Ti matrix. Atomic resolution images further reveal that the transformation can be mediated by either partial dislocations on basal planes or shear and atomic shuffle on the FCC1 1 0|HCP1 0 -1 0 interfaces. IMPACT STATEMENT: FCC-Ti's formation in pure α-Ti through deformation is controversial. In situ TEM observed FCC-Ti nucleation and growth in α-Ti matrix near the crack tip and revealed the mechanism. [ABSTRACT FROM AUTHOR]

The structure and the chemical composition of individual layers as well as of interfaces belonging to the two heterostructures M1 (BaFe12O19/YbFeO3/YSZ) and M2 (YbFeO3/BaFe12O19/YSZ) grown by pulsed laser deposition on yttria-stabilized zirconia (YSZ) substrates are deeply characterized by using a combination of methods such as high-resolution X-ray diffraction, transmission electron microscopy (TEM), and atomic-resolution scanning TEM with energy-dispersive X-ray spectroscopy. The temperature-dependent magnetic properties demonstrate two distinct heterostructures with different coercivity, anisotropy fields, and first anisotropy constants, which are related to the defect concentrations within the individual layers and to the degree of intermixing at the interface. The heterostructure with the stacking order BaFe12O19/YbFeO3, i.e., M1, exhibits a distinctive interface without any chemical intermixture, while an Fe-rich crystalline phase is observed in M2 both in atomic-resolution EDX maps and in mass density profiles. Additionally, M1 shows high c-axis orientation, which induces a higher anisotropy constant K1 as well as a larger coercivity due to a high number of phase boundaries. Despite the existence of a canted antiferromagnetic/ferromagnetic combination (T < 140 K), both heterostructures M1 and M2 do not reveal any detectable exchange bias at T = 50 K. Additionally, compressive residual strain on the BaM layer is found to be suppressing the ferromagnetism, thus reducing the Curie temperature (Tc) in the case of M1. These findings suggest that M1 (BaFe12O19/YbFeO3/YSZ) is suitable for magnetic storage applications. [ABSTRACT FROM AUTHOR]

Cluster-assembled nanostructured gold films are renowned for exhibiting neuromorphic properties, making them pivotal components in receptrons. Receptrons, which extend the perceptron framework, are specifically crafted for the classification of Boolean functions due to their distinctive properties. However, the current understanding of the phenomena underpinning this behavior is based on overall electrical measurements and speculative modeling. In situ biasing and heating transmission electron microscopy (TEM) imaging were performed to directly investigate the nanoscale origin of the films' neuromorphic properties. The films, resulting from the self-assembling of preformed gold nanoclusters, were deposited just above the percolation threshold to keep them electrically conductive and sufficiently thin for TEM observation and displayed a highly branched structure at the nano- and microscale. They were studied upon in situ biasing by imaging the whole area in between the biasing electrodes. The main biasing effect consisted of very confined, pronounced, and fast retraction of the branches, with concomitant formation of a few thick nanosized gold particles, and spatially limited rearrangement of the film structure. Similarly, upon overall in situ heating, the films retracted their branched structure without apparent mass loss and again with the formation of separated gold polycrystalline nanosized islands over the whole heating substrate. These general results indicate the likely occurrence of extremely intense and very local hot spots during in situ biasing, whose temperature and extension increased with the applied voltage. They also provide direct evidence of the local arrangements occurring in the film nanostructure and morphology due to electrical biasing and help understand the origin of the neuromorphic behavior of the cluster-assembled gold films. [ABSTRACT FROM AUTHOR]

To tailor electrical properties of often degenerate pristine CuI, Ni is introduced as alloy constituent. Cosputtering in a reactive, but also in an inert atmosphere as well as pulsed laser deposition (PLD), is used to grow NixCu1−xI$\left(\text{Ni}\right)_{x} \left(\text{Cu}\right)_{1 - x} \text{I}$ thin films. The Ni content within the alloy thin films is systematically varied for different growth techniques and growth conditions. A solubility limit is evidenced by an additional NiI2(H2O)6$\left(\text{NiI}\right)_{2} \left(\left(\text{(H}\right)_{2} \text{O)}\right)_{6}$ phase for Ni contents x≥0.31$x \geq 0.31$, observed in X‐Ray diffraction and atomic force microscopy by a change in surface morphology. Furthermore, metallic, nanoscaled nickel clusters, revealed by X‐Ray photoelectron spectroscopy and high‐resolution transmission electron microscopy (HRTEM), underpin a solubility limit of Ni in CuI. Although no reduction of charge carrier density is observed with increasing Ni content, a dilute magnetic behavior of the thin films is observed in vibrating sample magnetometry. Further, independent of the deposition technique, unique multilayer features are observed in HRTEM measurements for thin films of a cation composition of x≈0.06$x \approx $. Opposite to previous claims, no transition to n‐type behavior was observed, which was also confirmed by density functional theory calculations of the alloy system. [ABSTRACT FROM AUTHOR]

Silver is one of the most promising nanomaterials for plasmonic applications due to its low cost as well as the ease with which it can be prepared into nanoparticles with controlled size and shape. By now, it has already become clear that it is the shape and internal symmetry of nanoparticles that can significantly affect the scattering and absorption of a light wave, since without the formation of a strong dipole, these effects in nanoparticles will be insignificant. Therefore, the main objective of the study was a theoretical analysis of the processes of formation of the external and internal structure of silver nanoclusters obtained by some methods of physical synthesis. To do this, we studied high-resolution electron microscopy data for the initial and annealed silver nanoparticles formed on a carbon substrate by vacuum thermal evaporation and having sizes from 2,0 to 10,0 nm. It has been established that, as a result of annealing, the number of small nanoparticles (D< 3,5 nm) decreases by approximately 2 times, and the proportion of nanoparticles with icosahedral and decahedral faceting increases by approximately 1,5 times. Based on the analysis performed, conclusions were drawn about the possible features and mechanisms of formation of various types of symmetry in synthesized Ag nanoparticles.

In response of swift heavy ion (100 MeV I9+) irradiation, the irradiation‐induced disordering in nonstoichiometric pyrochlore composition (Nd1.8Zr2.2O7.1) was compared to that of stoichiometric composition Nd2Zr2O7. Both compositions were prepared through auto gel‐combustion followed by sintering under the identical conditions. Systematic analysis of the compositions before and after irradiation was performed with X‐ray diffraction (XRD), Raman spectroscopy, and plane‐view high‐resolution transmission electron microscopy (HRTEM) techniques. Irradiation caused pyrochlore to amorphous phase transformation was observed in both compositions except the slower rate of amorphization in Nd1.8Zr2.2O7.1. The amorphization was achieved as a consequence of isolated disordered track overlapping at higher ion fluence with the estimated track diameter 2.73 ± 0.05 and 3.46 ± 0.30 nm for Nd1.8Zr2.2O7.1 and Nd2Zr2O7, respectively, employing the framework of single‐ion impact model to XRD results. HRTEM micrographs also revealed the less prevalence of irradiation‐induced amorphization in Nd1.8Zr2.2O7.1 with the observed irradiation‐induced modified track region composed of defect‐rich pyrochlore structure, anion‐deficient fluorite structure, and amorphous domains; with the diameter of 3.0 ± 1.0 nm and 5.0 ± 1.0 nm in Nd1.8Zr2.2O7.1 and Nd2Zr2O7, respectively. The preexisting anion‐deficient fluorite structure in Nd1.8Zr2.2O7.1 helps in its epitaxial growth as recovered structure from melted ion track during irradiation‐induced rapid cooling. [ABSTRACT FROM AUTHOR]

Advanced high-resolution transmission electron microscopy methods have been used to study structural changes in a 51 at % Cu–Pd solid solution and identify the nature of compositional segregation in the disordered solid solution. The results can be used to account for the low rate of the ordering process near the equiatomic composition. [ABSTRACT FROM AUTHOR]

The structure and state of ultrafine particles of the active component in the composition of deposite single-metal- and bimetallic catalysts (Pt, Rh)/Al2O3 are studied using the X-ray method of pair distribution function analysis. It is shown that particles of metallic platinum Pt0 are formed in the Pt/Al2O3 catalyst, and particles of Pt0 and rhodium oxides are formed in the Pt–Rh/Al2O3 catalyst. The determined particle sizes are consistent with electron-microscopy data. [ABSTRACT FROM AUTHOR]

Technological opportunities are explored to enhance detection schemes in transmission electron microscopy (TEM) that build on the detection of single-electron scattering events across the typical spectrum of interdisciplinary applications. They range from imaging with high spatiotemporal resolution to diffraction experiments at the window to quantum mechanics, where the wave-particle dualism of single electrons is evident. At the ultimate detection limit, where isolated electrons are delivered to interact with solids, we find that the beam current dominates damage processes instead of the deposited electron charge, which can be exploited to modify electron beam-induced sample alterations. The results are explained by assuming that all electron scattering are inelastic and include phonon excitation that can hardly be distinguished from elastic electron scattering. Consequently, a coherence length and a related coherence time exist that reflect the interaction of the electron with the sample and change linearly with energy loss. Phonon excitations are of small energy (

Nickel-rich NiTiHf alloys that are heat treated to strengthen the microstructures with a dense distribution of Ni4Ti3 nanoprecipitates exhibit very high strengths and good quasi-static indentation resistance and rolling contact fatigue performances. To determine whether these properties are maintained at high rates of loading, in situ and recovery flyer plate impact shock experiments are performed on a Ni54Ti45Hf1 alloy at impact velocities ranging from approximately 150ms-1 (2.5 GPa) to 700ms-1 (12.40 GPa). Analysis of shocked samples indicated less cracking is observed to emanate from spall failures resulting from impact velocities greater than 250ms-1 (4.23 GPa), concurrent with observations of intragranular microbands within the microstructures. Analyses show clear evidence that, like responses to quasi-static loading, martensitic phase transformation occurs upon shock compression in all cases. However, dissimilarly, for the higher impact velocities it reverses upon stress release, leaving behind microbands that show no evidence for retained martensite and within which the Ni4Ti3 nanoprecipitates dissolved. These results indicate that strainrate dependence of these SMAs under shock loading is not only governed by the expected physics of rate-dependence of the martensitic transformations themselves but may also be enhanced by inelastic deformation mechanisms that result in precipitate dissolution. [ABSTRACT FROM AUTHOR]

Environmental nanoparticles are known to be present in various aquatic environments, exerting significant influences on water quality, particularly in water distribution systems. However, there has been a notable dearth of research on the presence and impact of environmental nanoparticles in mineral water, a unique water resource. In this study, we employed Nanoparticle Tracking Analysis (NTA) and conducted High-Resolution Transmission Electron Microscopy (HRTEM) to address this research gap. This groundbreaking study represents the first comprehensive exploration of environmental nanoparticles within natural mineral water from Zibo City, Shandong Province, China. The results of the NTA showed that the concentration of the particles was 5.5 × 105 particles/mL and the peak diameter of the size distribution was 180 nm. The HRTEM showed that the nanoparticles were granular, pinniform, rodlike, and flakey in shape, and some of the nanoparticles existed in aggregation. The energy-dispersive spectrometry results showed that most of the nanoparticles contained O, Mg, Ca, Si, Fe, Ti, and P, and some of them also contained F, V, S, and Mn. When combined with the characteristics of the selected area electron diffraction pattern, the nanoparticles were confirmed to be Ca-bearing nanoparticles, attapulgite nanorods, MnO2 nanosheets, and TiO2 nanoparticles. These findings shed light on a novel manifestation of elemental compositions in mineral water. Furthermore, considering the chemical and physical attributes of both the nanoparticles and mineral water, it is highly plausible that these environmental nanoparticles result from the weathering of minerals. The presence of these nanoparticles within mineral water offers a unique opportunity to advance our comprehension of nanoparticle behavior across diverse systems. Significantly, the realm of environmental nanoparticle science holds paramount importance for ongoing endeavors in ensuring water safety, enhancing treatment processes, and facilitating effective remediation procedures. [ABSTRACT FROM AUTHOR]

Phase-contrast transmission electron microscopy (TEM) is a powerful tool for imaging the local atomic structure of materials. TEM has been used heavily in studies of defect structures of two-dimensional materials such as monolayer graphene due to its high dose efficiency. However, phase-contrast imaging can produce complex nonlinear contrast, even for weakly scattering samples. It is, therefore, difficult to develop fully automated analysis routines for phase-contrast TEM studies using conventional image processing tools. For automated analysis of large sample regions of graphene, one of the key problems is segmentation between the structure of interest and unwanted structures such as surface contaminant layers. In this study, we compare the performance of a conventional Bragg filtering method with a deep learning routine based on the U-Net architecture. We show that the deep learning method is more general, simpler to apply in practice, and produces more accurate and robust results than the conventional algorithm. We provide easily adaptable source code for all results in this paper and discuss potential applications for deep learning in fully automated TEM image analysis.

The structure and the chemical composition of individual layers as well as of interfaces belonging to the two heterostructures M1 (BaFe12O19/YbFeO3/YSZ) and M2 (YbFeO3/BaFe12O19/YSZ) grown by pulsed laser deposition on yttria-stabilized zirconia (YSZ) substrates are deeply characterized by using a combination of methods such as high-resolution X-ray diffraction, transmission electron microscopy (TEM), and atomic-resolution scanning TEM with energy-dispersive X-ray spectroscopy. The temperature-dependent magnetic properties demonstrate two distinct heterostructures with different coercivity, anisotropy fields, and first anisotropy constants, which are related to the defect concentrations within the individual layers and to the degree of intermixing at the interface. The heterostructure with the stacking order BaFe12O19/YbFeO3, i.e., M1, exhibits a distinctive interface without any chemical intermixture, while an Fe-rich crystalline phase is observed in M2 both in atomic-resolution EDX maps and in mass density profiles. Additionally, M1 shows high c-axis orientation, which induces a higher anisotropy constant K1 as well as a larger coercivity due to a high number of phase boundaries. Despite the existence of a canted antiferromagnetic/ferromagnetic combination (T < 140 K), both heterostructures M1 and M2 do not reveal any detectable exchange bias at T = 50 K. Additionally, compressive residual strain on the BaM layer is found to be suppressing the ferromagnetism, thus reducing the Curie temperature (Tc) in the case of M1. These findings suggest that M1 (BaFe12O19/YbFeO3/YSZ) is suitable for magnetic storage applications.

This paper describes a study where an argon cold plasma jet, generated by a dielectric‐barrier discharge (DBD), is combined with nanosecond laser ablation (248 nm, 25 ns, 10 Hz) to deposit silver particle aerosols onto the substrate at atmospheric pressure. The deposition of the particle is examined using various microscopy techniques and absorption spectroscopy for the plasma jet produced by operating DBD in the normal and reversed mode. Plasma facilitated the deposition process by delivering the particle to the substrate and significantly influenced its morphology depending on the jet interaction, length, and substrate position. In both cases, the particles are clustered; however, there is less deposit for the plasma ignited in the reverse mode. The theoretical analysis of the deposition process is performed using ANSYS software and evaluated in terms of plasma‐induced flow velocity. This study infers that the hybrid plasma‐laser deposition scheme considered is attractive for material processing and deposition, especially overextended substrate distances, and for altering the properties of the deposited particles for practical utilization in surface‐enhanced Raman spectroscopy, solar cells, and catalysis. [ABSTRACT FROM AUTHOR]

Abstract This paper describes a study where an argon cold plasma jet, generated by a dielectric‐barrier discharge (DBD), is combined with nanosecond laser ablation (248 nm, 25 ns, 10 Hz) to deposit silver particle aerosols onto the substrate at atmospheric pressure. The deposition of the particle is examined using various microscopy techniques and absorption spectroscopy for the plasma jet produced by operating DBD in the normal and reversed mode. Plasma facilitated the deposition process by delivering the particle to the substrate and significantly influenced its morphology depending on the jet interaction, length, and substrate position. In both cases, the particles are clustered; however, there is less deposit for the plasma ignited in the reverse mode. The theoretical analysis of the deposition process is performed using ANSYS software and evaluated in terms of plasma‐induced flow velocity. This study infers that the hybrid plasma‐laser deposition scheme considered is attractive for material processing and deposition, especially overextended substrate distances, and for altering the properties of the deposited particles for practical utilization in surface‐enhanced Raman spectroscopy, solar cells, and catalysis.

Besides radiation resistance, thermal recovery of radiation damage provides another critical criterion to evaluate the host phase for immobilizing high-level waste (HLW) produced by nuclear plants. Despite the increasing investigations, a comprehensive atomic-scale understanding remains elusive on thermal annealing of radiation damage in ceramics. Here, using in situ heating high-resolution transmission electron microscopy, we investigate the thermal annealing of radiation damage in natural metamict titanite (CaTiSiO 5) caused by a high alpha decay dose from the incorporated U and Th during the geologic time. The recovery of the fully amorphous titanite precursor starts at 456 ℃ from the appearances of monoclinic nanoparticles 2–5 nanometers wide, and more nanoparticles form as the temperature gradually increases. At 1000 ℃, the amorphous phase recovers through epitaxial growth with titanite nanoparticles as templates. This study provides information for a unit-cell-scale understanding of the thermal stability of radiation damage in titanite-based ceramics, having significance for immobilizing HLW. • Thermal recovery of totally amorphous titanite was investigated by in situ heating HRTEM. • The recovery of amorphous titanite starts from the appearance of nanoparticles. • The epitaxial growth with a titanite nanoparticle being the template was observed in real time. [ABSTRACT FROM AUTHOR]

As much as 23 % of the world's energy is consumed in tribological contacts and reducing friction and wear can have a substantial environmental impact. However, the large majority of lubricants and additives, still based on crude oil, are becoming less and less sustainable: environmentally friendly alternatives are in dire need. Hypericin, a natural constituent of St. John's wort commonly known as antidepressant/antiviral/antibiotic medicinal, is here revealed to have an outstanding potential as friction modifier. Indeed, sustainable superlubricity performance, with friction coefficient below 0.01 under boundary lubrication, is observed when adding hypericin to glycerol to lubricate steel/SiC tribopairs. XPS and Raman spectroscopies revealed the formation of graphitic structures on surfaces rubbed in the presence of hypericin and High-Resolution-Transmission-Electron microscopy on focused ion-beam cross-sections evidenced the first stage of tribofilm polymerization and subsequent formation of graphene. First-principles calculations elucidate the thermodynamic forces driving graphene-formation induced by mechanochemical reactions. The process, tribologically promoted, was monitored in real-time by (ab-initio) molecular dynamics. Formation of graphene patches was found to strongly correlate with friction coefficient reductions up to the superlubricity limit. This work suggests an unconventional way towards formation of graphene-like materials through mechanochemistry and reveals the great potential of pharmacopeia-derived molecules as newly-emerging environment-friendly lubricant additives for industrial applications, opening new ways to formulate water-based lubricants, nowadays considered a strategic oils-alternative to reduce carbon footprint. [Display omitted] [ABSTRACT FROM AUTHOR]

Environmental nanoparticles are known to be present in various aquatic environments, exerting significant influences on water quality, particularly in water distribution systems. However, there has been a notable dearth of research on the presence and impact of environmental nanoparticles in mineral water, a unique water resource. In this study, we employed Nanoparticle Tracking Analysis (NTA) and conducted High-Resolution Transmission Electron Microscopy (HRTEM) to address this research gap. This groundbreaking study represents the first comprehensive exploration of environmental nanoparticles within natural mineral water from Zibo City, Shandong Province, China. The results of the NTA showed that the concentration of the particles was 5.5 × 105 particles/mL and the peak diameter of the size distribution was 180 nm. The HRTEM showed that the nanoparticles were granular, pinniform, rodlike, and flakey in shape, and some of the nanoparticles existed in aggregation. The energy-dispersive spectrometry results showed that most of the nanoparticles contained O, Mg, Ca, Si, Fe, Ti, and P, and some of them also contained F, V, S, and Mn. When combined with the characteristics of the selected area electron diffraction pattern, the nanoparticles were confirmed to be Ca-bearing nanoparticles, attapulgite nanorods, MnO2 nanosheets, and TiO2 nanoparticles. These findings shed light on a novel manifestation of elemental compositions in mineral water. Furthermore, considering the chemical and physical attributes of both the nanoparticles and mineral water, it is highly plausible that these environmental nanoparticles result from the weathering of minerals. The presence of these nanoparticles within mineral water offers a unique opportunity to advance our comprehension of nanoparticle behavior across diverse systems. Significantly, the realm of environmental nanoparticle science holds paramount importance for ongoing endeavors in ensuring water safety, enhancing treatment processes, and facilitating effective remediation procedures.

A systematic investigation of magnetic nanoparticles and the formation of a core-shell structure, consisting of multiple maghemite (γ-Fe2O3) nanoparticles as the core and silica as the shell, has been performed using various techniques. High-resolution transmission electron microscopy clearly shows isolated maghemite nanoparticles with an average diameter of 13 nm and the formation of a core-shell structure. Low temperature Mössbauer spectroscopy reveals the presence of pure maghemite nanoparticles with all vacancies at the B-sites. Isothermal magnetization and zero-field-cooled and field-cooled measurements are used for investigating the magnetic properties of the nanoparticles. The magnetization results are in good accordance with the contents of the magnetic core and the non-magnetic shell. The multiple-core γ-Fe2O3 nanoparticles show similar behavior to isolated particles of the same size.

A systematic investigation of magnetic nanoparticles and the formation of a core-shell structure, consisting of multiple maghemite (γ-Fe2O3) nanoparticles as the core and silica as the shell, has been performed using various techniques. High-resolution transmission electron microscopy clearly shows isolated maghemite nanoparticles with an average diameter of 13 nm and the formation of a core-shell structure. Low temperature Mössbauer spectroscopy reveals the presence of pure maghemite nanoparticles with all vacancies at the B-sites. Isothermal magnetization and zero-field-cooled and field-cooled measurements are used for investigating the magnetic properties of the nanoparticles. The magnetization results are in good accordance with the contents of the magnetic core and the non-magnetic shell. The multiple-core γ-Fe2O3 nanoparticles show similar behavior to isolated particles of the same size.

The R3 space group inherently lacks 2110, m001 and symmetry operations. However, in crystals with R3 symmetry, these transformations produce 'pseudoplanes' with the same interplanar spacing and angles as the original crystallographic planes, causing a lack of uniqueness in the electron diffraction (ED) pattern. The difference in atomic arrangements of pseudoplanes and original planes is reflected in the intensities of diffraction spots; it is hard to differentiate in standard ED patterns, frequently causing wrong assignment of the zone axes. The implications of this ambiguity in analysis of crystal orientations are discussed in detail and a suitable routine to follow while indexing R3 ED patterns is proposed. [ABSTRACT FROM AUTHOR]

Undoped ZnO and Zn1−xGdxO nanoparticles are made using a sono‐chemical co‐precipitation approach. X‐ray diffraction and transmission electron microscopy investigations verified the formation of a wurtzite structure with spherical geometry. All the samples are found to be nanocrystalline by transmission electron microscopy, with crystallite diameters ranging from 14 to 22 nm. The optical constants are calculated via diffuse reflectance spectroscopy. The Urbach energy and photoluminescence spectrum both showed that all doped nanoparticle samples contained defects and disorder due to vacancies. The band structure finding suggest that the forbidden gap of ZnO may change due to the conduction band shift, Burstein‐Moss shift, and shrinkage effect. The near band emission in the ultraviolet region and deep level emission of the photoluminescence spectrum are both strong and decreased with increasing Gd3+ concentration. Studies using X‐ray absorption near edge spectroscopy revealed that the host nano‐lattice Zn sites are substituted with Gd3+ cations to preserve the symmetry with minor distortion. Investigations into charge transfer through the oxygen bands (Gd‐O‐Zn) are made using O K‐edge spectra. The defect emission bands identified through Gd doping indicated that these emissions may be changed for ZnO samples, which could be advantageous for applications in phosphors and light‐emitting devices. [ABSTRACT FROM AUTHOR]

The effects of natural ageing treatment prior to artificial ageing treatment on the microstructures and mechanical properties of AA7075 Al-5.7Zn-2.6Mg-1.5Cu-0.18Cr-0.08Mn-0.05Si-0.17Fe (wt.%) aluminum alloy have been investigated. The hardness of solution-treated samples (91.0 HV) profoundly increased to 146.8 HV after 7 days of natural ageing. The purpose of the present work was to examine the kinetic hardening evolution in subsequent artificial ageing treatments of samples naturally aged for 7 days and their counterparts without natural ageing. The former were labelled as NA-7d samples, and the latter, NA-0d samples. After artificial ageing at 120 °C for 2 h, the hardness of NA-0d samples increased rapidly to 148.2 HV, which was approximately the same as that of the specimens with natural ageing for 7 days, compensating for the prior state of lower hardness without natural ageing. After being treated at 120 °C for 16 h, the ultimate tensile strength (UTS) and yield strength (YS) of NA-7d reached the highest value, respectively, 601 MPa and 539 MPa, followed by a slight decrement of UTS when aged to 24 h. On the other hand, NA-0d specimens aged at 120 °C for 16 and 24 h showed nearly the same UTS (598 MPa); the former possessed YS of 538 MPa, and the latter, 545 MPa. The results presumably reveal that the peak ageing condition for NA-0d samples can be achieved under 24 h ageing at 120 °C. Under the same treatment at 120 °C for 24 h, the size of η' phase in NA-7d sample (with a length of 4.96 nm) coarsened and grew larger than that in NA-0d sample (with a length of 3.46 nm). In addition, some η' phase in the NA-7d sample was found to be transformed into the η2 phase. The results indicated that the naturally aged specimens (NA-7d) reached the peak ageing condition earlier, but did not significantly enhance the UTS in AA7075 aluminum alloy, as compared to the samples without prior natural ageing (NA-0d). [ABSTRACT FROM AUTHOR]

The DLC coating of samples produced by additive manufacturing with complex shapes is a challenge but also shows the possibility of obtaining a diffusive barrier for biomedical applications. In this study, stochastic porous structures based on Voronoi tessellation were fabricated using binder jetting technology from 316L SS powder and modified using DLC coating. The DLC coating was deposited using the RF PACVD technology. The chamber pressure was 40 Pa with a methane gas flow rate of 60 sccm. The negative bias voltage was 700 V. The deposition time was 5 min. Dimensional analysis was performed using optical microscopy. Surface morphology and topography were evaluated using SEM and confocal microscopy. Raman spectroscopy was used to examine the chemical structure of DLC coating. Finally, the HR TEM was used to evaluate the physicochemical characterization of the DLC coating. The interconnected complex spatial network of the Voronoi structure was accurately duplicated by the binder jetting technology. The obtained substrates were characterized by high roughness (Ra = 6.43 µm). Moreover, the results indicated that the conditions of the RF PACVD process allow for the deposition of the continuous and tightened DLC coating with a thickness from 30 nm to 230 nm and defined the content of Cr2O3 and SiO2. [ABSTRACT FROM AUTHOR]

In the present work, chromium(III) oxide (Cr2O3) and potassium oxide (K2O) nanoparticles (NPs) were synthesized using the combustion method. Mixed oxides of varying concentrations in the form of (1-x)Cr2O3/xK2O (x = 0.1, 0.3, 0.5, and 0.7) were prepared. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and optical measurements were used to investigate the properties of NPs. XRD indicates that the grain size of the mixed oxides decreased as the K2O content increased. Additionally, HRTEM revealed several types of shapes, such as hexagonally shaped NPs. The optical measurements showed a blue shift, indicating that the band structure was slightly modified during the Cr2O3/xK2O mixing. The optical band gap obeys the direct allowed transition and varies from 2.29 to 2.59 eV as the K2O ratio in the composites increases from x = 0.1 to 0.7. The (1-x)Cr2O3/xK2O NPs were used as catalysts in wastewater during a photocatalytic process. Orange G was chosen as an impurity in the water. The absorbance curves of Orange G in the water were measured at different times in the presence of the same quantity of Cr2O3/xK2O NPs. It was found that after 120 min, the efficiency reached 11% and 33% for (1-x)Cr2O3/xK2O NPs with x = 0.1 and 0.7, respectively. Furthermore, the experimental results were analyzed by pseudo-first-order model. A first-order kinetic model had the best fit for the (1-x)Cr2O3/xK2O NPs. The strongest relationship occurred with a composition of 0.1Cr2O3/0.7K2O. The formed composites could be used to degrade organic dy es for water purification. [ABSTRACT FROM AUTHOR]

Bilayer graphene (BLG) has recently been used as a tool to stabilize encapsulated single sheets of various layered materials and tune their properties. It was also discovered that the protecting action of graphene sheets makes it possible to synthesize completely new two-dimensional materials (2DMs) inside the BLG by intercalating various atoms and molecules. In comparison to the bulk graphite, BLG allows for easier intercalation and a much larger increase in the interlayer separation of the sheets. Moreover, it enables studying the atomic structure of the intercalated 2DM by using high-resolution transmission electron microscopy. In this review, we summarize the recent progress in this area, with a special focus on new materials created inside BLG. We compare the experimental findings with the theoretical predictions, pay special attention to the discrepancies, and outline the challenges in the field. Finally, we discuss unique opportunities offered by intercalation into 2DMs beyond graphene and their heterostructures.

The structure and morphology of vertically aligned CNT (VACNT) arrays grown by CVD on Fe–Al2O3/Si(001) substrates are studied using scanning and high-resolution transmission electron microscopy (HRTEM) methods and Raman scattering. It is established that reproducible growth of continuous VACNT arrays is achieved only if the deposited Fe layer is at least 2 nm thick, while the particle size of the catalyst formed by annealing at 700 °C varies in a range of 2-10 nm and the array consists mainly of single- and double-walled CNTs with a diameter of 1-6 nm. The Raman spectrum is characterized by the presence of a radial breathing mode in the region 95-232 cm–1 and an intense G mode that is split into peaks at 1594 cm–1 and 1568 cm–1 upon laser excitation at the wavelength λ = 785 nm. According to the literature data, both modes indicate predominantly semiconductor nature of tubes in the array. The measured surface resistance of the VACNT array is 320±20 Ω/□. [ABSTRACT FROM AUTHOR]

The occurrence of oxygen‐driven metal–insulator‐transition (MIT) in SrNbO3 (SNO) thin films epitaxially grown on (110)‐oriented DyScO3 has been reported. SNO films are fabricated by the pulsed laser deposition technique at different partial O2 pressure to vary the oxygen content and their structural, optical, and transport properties are probed. SNO unit cell has been found to shrink vertically as the oxygen content increases but keeping the epitaxial matching with the substrate. The results of Fourier‐transform infra‐red spectroscopy show that highly oxygenated SNO samples (i.e., grown at high oxygen pressure) show distinct optical conductivity behavior with respect to oxygen deficient films, hence demonstrating the insulating character of the formers with respect to those fabricated with lower pressure conditions. Tailoring the optical absorption and conductivity of strontium niobate epitaxial films across the MIT will favor novel applications of this material. [ABSTRACT FROM AUTHOR]

It is of great significance to study the correlation between the crystallite structure and the pore structure of coal at different ranks for evaluating the coal seam gas storage capacity. The crystallite structure parameters of 8 kinds of coal samples were obtained by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD) experiments, and the pore structure characteristics of the coals were analyzed. The measured crystallite structure parameters and pore structure parameters were plotted for analysis. The experimental results show that there is a certain relationship between the evolution of coal aromatic structure and the evolution of coal pore structure. The crystallite component parameters and pore structure parameters were analyzed. In the coal whose aromatic structure is dominated by benzene and naphthalene, the pore structure of the coal is mainly dominated by mesopores and macropores, and there are a large number of mesopores and macropores, but almost no micropores. In the coal whose aromatic structure is dominated by 2 × 2 and above aromatic structure, the pore structure of the coal gradually changes to be dominated by micropores, and the number of micropores increases, while the number of mesopores and macropores decreases. Taking La and Nave as examples, the La corresponding to the lowest total pore volume and total specific surface area is about 1.93 nm, which is just in the evolution stage of para-bituminous coal. The crystallite lattice parameters and pore structure parameters were analyzed. In the evolution process from lignite to para-bituminous coal, the evolution of pore structure is dominated by the decrease of pore structure of mesopores and macropores, while the increase of micropores is not obvious, with the increase of crystallite height, crystallite diameter, the average number of the effective aromatic layer, and other parameters. In the evolution process from para-bituminous coal to anthracite, with the continuous increase of the four parameters, the pore structure evolution is dominated by the increase of micropore pore structure, while the change of mesopores and macropores is not obvious. [ABSTRACT FROM AUTHOR]

With the growing applications of temporally resolved electron microscopy for probing basic phenomena and reducing beam-induced damage, a multifaceted introduction to the field of ultrafast transmission electron microscopy is provided. This primer includes techniques and equipment as well as implementation perspectives. Historical developments and recent technical advances will provide insight into ultrafast capabilities for research as well as educate electron microscopists on the general techniques. This technology review also includes applications enabled by ultrafast techniques using various sample stimuli from multidisciplinary fields. [ABSTRACT FROM AUTHOR]

The effects of natural ageing treatment prior to artificial ageing treatment on the microstructures and mechanical properties of AA7075 Al-5.7Zn-2.6Mg-1.5Cu-0.18Cr-0.08Mn-0.05Si-0.17Fe (wt.%) aluminum alloy have been investigated. The hardness of solution-treated samples (91.0 HV) profoundly increased to 146.8 HV after 7 days of natural ageing. The purpose of the present work was to examine the kinetic hardening evolution in subsequent artificial ageing treatments of samples naturally aged for 7 days and their counterparts without natural ageing. The former were labelled as NA-7d samples, and the latter, NA-0d samples. After artificial ageing at 120 °C for 2 h, the hardness of NA-0d samples increased rapidly to 148.2 HV, which was approximately the same as that of the specimens with natural ageing for 7 days, compensating for the prior state of lower hardness without natural ageing. After being treated at 120 °C for 16 h, the ultimate tensile strength (UTS) and yield strength (YS) of NA-7d reached the highest value, respectively, 601 MPa and 539 MPa, followed by a slight decrement of UTS when aged to 24 h. On the other hand, NA-0d specimens aged at 120 °C for 16 and 24 h showed nearly the same UTS (598 MPa); the former possessed YS of 538 MPa, and the latter, 545 MPa. The results presumably reveal that the peak ageing condition for NA-0d samples can be achieved under 24 h ageing at 120 °C. Under the same treatment at 120 °C for 24 h, the size of η’ phase in NA-7d sample (with a length of 4.96 nm) coarsened and grew larger than that in NA-0d sample (with a length of 3.46 nm). In addition, some η’ phase in the NA-7d sample was found to be transformed into the η2 phase. The results indicated that the naturally aged specimens (NA-7d) reached the peak ageing condition earlier, but did not significantly enhance the UTS in AA7075 aluminum alloy, as compared to the samples without prior natural ageing (NA-0d).

The evolution of carbon nanostructures during coal graphitization was investigated. The X-ray diffraction (XRD) results showed that amorphous and microcrystalline carbon coexist in anthracite and meta-anthracite, and the latter has a higher proportion of microcrystalline carbon; additionally, semi-graphite and coal-based graphite are mostly composed of crystalline carbon. Coal graphitization starts in anthracite, accompanied by an increase in crystallite size and a decrease in interplanar spacing nonlinearly, especially in semi-graphite, and a large ordered structure is formed in coal-based graphite. The high-resolution transmission electron microscopy (HRTEM) results intuitively reveal the graphitization process by false-colored microphotography, and both the XRD and HRTEM results indicate similar evolution paths. Four types of carbon nanostructures, namely, amorphous, turbostratic, concentric and graphitic-like structures, are identified according to their morphology. Aromatic fringes are arranged randomly in the amorphous structure and are composed of amorphous carbon; local ordering occurs in the turbostratic structure and is commonly observed in anthracite and meta-anthracite. In addition, a concentric structure with hollow pores and parallel annular aromatic fringes was observed, indicating multiple preferred orientations, and the graphitic-like structure was composed of parallel aromatic fringes. Micropores provide the necessary adjustment space for the ordered conversion of carbon nanostructures, and the flattening and merging of micropores may contribute to the enhancement of graphitization. [Display omitted] • A nonlinear evolution of macrocrystalline size occurs during coal graphitization. • Four distinct types of carbon nanostructures were delineated. • Coal graphitization is accompanied by carbon nanostructure transformation. • The flattening and merging of micropores contribute to coal graphitization. [ABSTRACT FROM AUTHOR]

Abstract High-dispersed nanoscale Cu precipitates often contribute to extremely high strength due to precipitation hardening, and whereas usually lead to degraded toughness for especially ferritic steels. Hence, it is important to understand the formation behaviors of the Cu precipitates. High-resolution transmission electron microscopy (TEM) is utilized to investigate the structure of Cu precipitates thermally formed in a high-strength low-alloy (HSLA) steel. The Cu precipitates were generally formed from solid solution and at the crystallographic defects such as martensite lath boundaries and dislocations. The Cu precipitates in the same aging condition have various structure of BCC, 9R and FCC, and the structural evolution does not greatly correlate with the actual sizes. The presence of different structures in an individual Cu precipitate is observed, which reflects the structural transformation occurring locally to relax the strain energy. The multiply additions in the steel possibly make the Cu precipitation more complex compared to the binary or the ternary Fe–Cu alloys with Ni or Mn additions. This research gives constructive suggestions on alloying design of Cu-bearing alloy steels.

In this article, we focused on the interaction study of chemically fabricated PbS quantum dots (QDs) with model protein bovine serum albumin (BSA). The absorption of the PbS QDs has been observed in the NIR region at λ ≈ 1453 nm with a band gap ≈ 0.91 eV. The average size of the PbS QDs from the HRTEM study was found to be 3.5 nm with well crystalline nature and face-centered cubic (FCC) crystal phase as observed from the XRD study. The ground state complex formation between BSA and PbS QDs at room temperature has been observed and discussed from UV–VIS spectroscopy. The bioconjugate of PbS QDs-BSA formation has been occurring within a colony by the assembly of mesh formation as observed from the HRTEM images. The emission quenching of albumin in the presence of PbS QDs was occurring as observed from the emission spectrum. The energy transfer between serum protein and PbS QDs has been observed. The photo-current within the pure PbS QDs and PbS QDs-BSA conjugate was observed in the nA and µA range, respectively, under photo-conducting process. The albumin corona formation on the PbS QD was accounted for under the four temperatures (T = 300 K, 305 K, 311 K, 316 K) from the dynamic light scattering study. [ABSTRACT FROM AUTHOR]

In order to better understand the in-flame diesel soot oxidation processes, soot particles at the oxidation-dominant periphery of diesel spray flame were sampled via newly developed suck type soot sampler employing a high-speed solenoid valve, and their morphology and nanostructure were observed and analyzed via high-resolution transmission electron microscopy. A single-shot diesel flame for the soot sampling experiment was achieved in a constant-volume vessel under a diesel-like condition (9.5 kg/m³, 2.5 MPa, 1070K, and 21%O2). Morphology of soot aggregates, inner-core/outer-shell structure of primary particles within the aggregates, and carbon crystallite nanostructures within the primary particles were compared between the soot aggregates sampled at the diesel flame core near the central axis and the oxidationdominant flame periphery. The morphology observation and the inner-core/outer-shell structure characteristics obtained by newly employed concentricity analysis showed that the flame core soot exhibits graphitic primary particles with clear outlines and boundaries similarly observed for engine exhaust soot. Each primary particle contained a well-defined inner core surrounded by thick graphitic outer shell. On the contrary, the flame periphery soot exhibited smaller primary particles with unclear and lumpy outlines containing multiple obscured inner cores surrounded by thinner outer shell. The analysis of carbon crystallite nanostructures within the primary particles showed that the in-flame soot nanostructure shifts toward amorphous from the flame core to the periphery. On the contrary, the engine soot nanostructure in the literature shifts toward graphitic from the in-cylinder TDC to the exhaust, exhibiting the opposite trend with the inflame soot. These results suggest that the engine exhaust soot has not experienced the rapid in-flame oxidation by OH radicals and is therefore considered not to be the remains of incomplete or partial oxidation, but the runaways escaped from the flame core to the exhaust without being attacked by the in-flame OH radicals. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h‐BN) has been generally interpreted as having an AA stacking sequence. Evidence is presented in this article indicating that typical commercial h‐BN platelets (∼10–500 nm in thickness) exhibit stacks of parallel nanosheets (∼10 nm in thickness) predominantly in the AB sequence. The AB‐stacked nanosheet occurs as a metastable phase of h‐BN resulting from the preferred texture and lateral growth of armchair (110) planes. It appears as an independent nanosheet or unit for h‐BN platelets. The analysis is supported by simulation of thin AB films (2–20 layers), which explains the unique X‐ray diffraction pattern of h‐BN. With this analysis and the role of pressure in commercial high‐pressure high‐temperature sintering (driving nucleation and parallelizing the in‐plane crystalline growth of the nuclei), a growth mechanism is proposed for 2D h‐BN (on a substrate) as 'substrate‐induced 2D growth', where the substrate plays the role of pressure. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) raised substantial interest in the past two decades due to its unique properties beyond those of pristine graphene, including electronic energy bandgap, hydrophilic behavior, and numerous anchoring sites required for functionalization. In addition, GO is found to be a cheap mass‐production source for the formation of the pristine graphene. However, the presence of numerous clusters containing oxygen functional groups (called debris) on the GO surface hinders the GO integration in electronic devices. Herein, a simple method aimed to reduce the density of oxygen debris weakly bonded to the surface is presented. The method consists of minimal treatments, like sonication and/or water rinsing processes. Whereas this simple method removed epoxy and hydroxyl oxygen groups weakly attached to the graphene matrix, the double CO bonds are almost not affected by the applied treatment, as demonstrated by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Scanning tunneling microscopy and high‐resolution transmission electron microscopy measure the designated nonuniform distribution of the oxidation sites, appearing as clusters concentrated preferentially on GO‐defected regions, albeit separated by pristine graphene areas. The results should have an impact in the implementation of GO in electronic devices deposited on different substrates. [ABSTRACT FROM AUTHOR]

Amorphous carbon films (ACFs) have recently emerged as one of the best candidates for etching-resistant hardmask materials in advanced semiconductor manufacturing processes. Etching resistivity of ACFs is known to be improved by controlling the relative abundance between sp2 and sp3 bonds. We have investigated the relative abundance between sp2 and sp3 bonds in several ACFs, fabricated by plasma-enhanced chemical vapor deposition at different temperatures, which were analyzed by using X-ray photoemission spectroscopy, Raman spectroscopy, and transmission electron microscopy. We found that the relative abundance of sp2 bond increased as the growth temperature was raised. Furthermore, the ACFs eventually evolved into nano-crystalline graphite with increasing growth temperature. • Amorphous carbon films were grown by plasma-enhanced chemical vapor deposition at different temperatures. • Relative abundance of sp2 bonds increased with increasing growth temperature. • Evolution of amorphous carbon films into nano-crystalline graphite with increasing growth temperature was observed. • Amorphous carbon films grown at lower temperatures provided better etching resistivity. [ABSTRACT FROM AUTHOR]