Field-emission Microscopy Research Articles

Effect of traps and conductive pathways on electron emission from copper broad-area composite emitters

This study investigates electron emission from copper broad-area emitters (CBAEs) and copper broad-area composite emitters (CBACEs) based on the principles of trapping and conductive pathways. Emission current measurements were conducted on two CBACEs, which consisted of copper coated with a 300–400 μm epoxy resin and subjected to high voltages up to 15 kV. The research specifically examines the ‘switch-on’ and collapse phenomena occurring within the epoxy layer. Field emission microscopy (FEM) was utilized in a high-vacuum environment ( 10−6 mbar) to observe these effects. A comprehensive model is developed to explain the formation of conductive pathways within the epoxy layer, allowing electrons transfer from traps to the surface. This model treats the composite emitter as a trap-rich capacitor. The study also clarifies the effects of trap density and epoxy layer thickness on the collapse process. To gain a deeper understanding of the model, changes in the I-V curve were examined. Simulations, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) images, and Fourier transform infrared spectroscopy (FTIR) analysis were employed to understand the collapse mechanism of the epoxy collapse. Additionally, Nyquist and Cole–Cole plots were analyzed across frequencies ranging from 1 to 106 Hz before and after applying a high electric field on the samples, revealing changes in the capacitive component and the role of diodes in the formation of conductive channels.

Antimicrobial Peptide Octoprohibitin-Encapsulated Chitosan Nanoparticles Enhanced Antibacterial Activity against Acinetobacter baumannii

Background: This study focused on evaluating the physiochemical characteristics and antibacterial activity of Octoprohibitin-encapsulated CNPs (Octoprohibitin-CNPs) against Acinetobacter baumannii. Methods: Octoprohibitin was encapsulated into CNPs via ionotropic gelation with carboxymethyl chitosan (CMC) and low molecular weight chitosan (CS). Octoprohibitin-CNPs were dispersed in phosphate-buffered saline and the release kinetic profile was determined. Then Octoprohibitin-CNPs were examined using field-emission transmission electron microscopy and physicochemical characterization was performed. Antibacterial activity of Octoprohibitin-CNPs against A. baumannii was evaluated. Biofilm inhibition and eradication assays were performed using the crystal violet (CV) staining-based method for biofilm quantification. Results: The average diameter, zeta potential, encapsulation efficiency, and loading capacity of Octoprohibitin-CNPs were 244.5 ± 21.97 nm, +48.57 ± 0.38 mV, and 85.7% and 34.2%, respectively. TEM analysis imaging revealed that Octoprohibitin-CNPs are irregularly shaped, with fewer aggregates than CNPs. Octoprohibitin-CNPs exhibited a biphasic release pattern, characterized by an initial rapid phase followed by a sustained release over time, extending up to 93.68 ± 6.48% total release until 96 h. In vitro, Octoprohibitin-CNPs showed lower cytotoxicity compared to Octoprohibitin alone. Time-kill kinetic and bacterial viability reduction assays showed Octoprohibitin-CNPs exhibited slightly higher antibacterial activity against A. baumannii than Octoprohibitin. Conclusions: Octoprohibitin-CNP-treated A. baumannii exhibited higher levels of morphological deviation, increased membrane permeability, and the production of reactive oxygen species, as well as antibiofilm activity with greater biofilm inhibition and eradication than Octoprohibitin. These findings show that Octoprohibitin-CNPs perform better against A. baumannii compared to Octoprohibitin alone.

Comprehensive analysis of charge carriers dynamics through the honeycomb structure of graphite thin films and polymer graphite with applications in cold field emission and scanning tunneling microscopy

Polymer graphite electron sources have performed satisfactorily as field emission emitters and scanning tunneling microscopy probes in the past few years. However, the emission process was characterized by limited total emission currents. This paper introduces the elemental, vibrational, electronic structure, and optical analysis of polymer graphite and glass-graphite composite field emission cathodes to study these limitations. Moreover, the field emission characteristics are studied including the changes in the potential energy barrier of the used materials and structures. Among the studied structures, the cathodes prepared from graphite thin films deposited on a micropointed glass substrate (film-GMF) showed superior performance as random field emission arrays. This includes obtaining much higher emission current values ≈ 20 times) and lower threshold voltages ≈ 1/2) compared to the results obtained from polymer graphite samples. The enhancement factor in such emitters is believed to be the three-dimensional honeycomb structure of graphite. Moreover, the study includes applying graphite coatings to tungsten nano-field emission cathodes and scanning tunneling microscopy probes, which improves the performance of such cathodes/probes in both microscopic techniques.

Effect of Grease Composition on Impact-Sliding Wear

Impact-sliding experiments were performed by using four self-made lithium-based greases, namely Yangtze Grease 1, Yangtze Grease 2, Yangtze Grease 3, and Yangtze Grease 4. The influence of base oil viscosity, thickener content, and morphology of thickener fiber clusters on the lubricating state were visually explored, combined with field-emission microscopy and two-light interference technology. The grease film distribution at the middle section was measured using Dichromatic Interference Intensity Modulation (DIIM) software. All experiments were executed in a completely flooded environment. The results show that among the components of grease, the base oil’s viscosity has the greatest impact on the anti-wear performance of the grease. As the viscosity of the base oil increases, the grease exhibits better anti-wear performance. The grease film thickness under the condition of high-viscosity base oil is about 10 times higher than that under the condition of low-viscosity base oil. Secondly, the content of thickener in the grease needs to be controlled within a reasonable range. The experiments indicate that the effect of thickener content on the grease’s film-forming properties becomes more pronounced at higher speeds. From the experiment using YG 4, it can be seen that a higher thickener content under high-speed conditions increases the thickness of the lubricating grease film by about 10 times. The dimensions of the thickener fibers and the density of their entanglement structure significantly influence the rheological properties and load-bearing capacity of the grease. Larger fiber sizes and higher entanglement densities result in reduced grease fluidity and recovery but enhance its load-bearing capabilities. In order to obtain the best anti-wear performance during impact-sliding motion, the size of the thickener fiber and the density of the entanglement structure need to be controlled within an appropriate range.

Physiochemical and electrical activities of nano copper oxides synthesised via hydrothermal method utilising natural reduction agents for solar cell application

Abstract The aim of this study is to explore the potential compatibility of copper oxide nano-powders synthesised via hydrothermal method for solar cell applications by triggering a reaction between copper acetate and various reducing agents derived from natural resources, including Arabic gum, molasses, starch, and vinegar. X-ray diffraction analysis revealed the crystalline phases of the synthesised materials, indicating the successful synthesis of copper oxide material, which was confirmed by identifying patterns that matched specific copper oxide phases. Fourier transform infrared spectroscopy was employed to analyse the molecular vibrations and chemical compounds present in the reducing agents. The reducing properties of the selected materials and their capacity to convert copper acetate into copper oxide were validated. Field-emission microscopy and transmission electron microscopy analyses of the synthesised copper oxide nanoparticles (NPs) revealed variations in particle size and morphology. These variations were dependent on the particular reducing agent utilised during synthesis. Moreover, the carrier concentration, mobility, and resistivity were evaluated as the electrical properties of the spin-coated copper oxide thin films. Hall effect analysis determined that the choice of reducing agent significantly influenced the carrier concentration (n) and mobility (µ) of the films. Remarkably, nano copper oxide films synthesised using starch exhibited irregular spherical grains with porous surfaces. Starch-synthesised samples showed the highest conductivity of n = 1.2 × 1019 cm−3 when compared with those synthesised with other reducing agents. This suggests that the porous surfaces in the starch-synthesised films may have contributed to their enhanced conductivity compared to films synthesised with alternative reducing agents. In summary, the findings emphasised the influence of the reducing agent on the size, morphology, and electrical conductivity of the copper oxide NPs.

Impact of annealing on structural and optical properties of sol-gel derived samarium silica nanocomposites

The pursuit of finely tuned material properties has driven the exploration of annealing strategies in the context of Samarium Silica Nanocomposites (Sm-SiO2 NCs) synthesized through the sol-gel route. This study unveils novel insights into the influence of optimized annealing protocols on the structural and functional evolution of these advanced nanocomposites. Through meticulous experimentation, we establish that controlled temperature annealing plays a pivotal role in tailoring the microstructure and properties of Sm-SiO2 NCs. The judicious manipulation of annealing parameters, including temperature duration, and atmosphere, orchestrates distinct transformations in the composite architecture. Field emission microscopy and structural analysis reveal that precise annealing promotes the consolidation of nanoscale domains, leading to improved crystallinity and enhanced connectivity between samarium species and the silica matrix. Moreover, the annealing-induced modifications extend beyond structural aspects to influence functional properties, an increase in crystallite size was observed from 15 nm to 43 nm as an effect of annealing. Our findings illustrate a remarkable enhancement in luminescence intensity as a consequence of optimized annealing, showcasing the potential for tailored photonic applications. These revelations are supported by a comprehensive suite of analytical techniques, including X-ray diffraction, Fourier transform infra red,\Field emission with Energy dispersive x-ray and photoluminescence spectroscopy. The synthesis-annealing synergy not only advances our fundamental understanding of nanocomposite evolution but also furnishes a pathway towards designing multifunctional materials with precision-engineered attributes.

Revealing the mechanism of citral induced entry of Vibrio vulnificus into viable but not culturable (VBNC) state based on transcriptomics

Citral has attracted much attention as a safe and effective plant-derived bacteriostatic agent. However, the ability of citral to induce the formation of VBNC state in Vibrio vulnificus has not been evaluated. In the present study, V. vulnificus was shown to be induced to form the VBNC state at 4.5 h and 3 h of citral treatment at 4MIC and 6MIC. Moreover, the citral-induced VBNC state of V. vulnificus maintained some respiratory chain activity and was able to recover well in both APW media, APW media supplemented with 5 % (v/v) Tween 80 and 2 mg/mL sodium pyruvate. Field emission and transmission electron microscopy showed that the external structure of the citral-induced VBNC V. vulnificus cells was shortened to short rods, with folded cell membrane, rough cell surface, and dense cytoplasm and loose nuclear material in the internal cell structure. In addition, the possible molecular mechanisms of citral-induced formation and recovery of V. vulnificus in the VBNC state were explored by transcriptomics. Transcriptome analyses revealed that 1118 genes were significantly altered upon entry into the VBNC state, and 1052 genes were changed after resuscitation. Most of the physiological activities related to energy production were inhibited in the citral-induced VBNC state of V. vulnificus; however, the bacteria retained its pathogenicity. The citral-induced resuscitation of V. vulnificus in the VBNC state selectively restored the activity of some genes related to bacterial growth and reproduction. Meanwhile, the expression levels of other genes may have been influenced by citral-induced resuscitation after the formation of the VBNC state. In conclusion, this study evaluated and analyzed the ability and possible mechanism of citral on the formation of VBNC state and the recovery of VBNC state of V. vulnificus, and made a comprehensive assessment for the safety of citral application in food production.

Non-enzymatic electrochemical sensor based on ZnO nanoparticles/porous graphene for the detection of hypoxanthine in pork meat

In this study, we developed a pioneering non-enzymatic electrochemical sensor utilizing a flexible porous graphene electrode modified with ZnO nanoparticles (ZnO/fPGE sensor) to assess hypoxanthine (HXA) content in pork at post-mortem time. The ZnO/fPGE sensor was synthesized via hydrothermal method and direct laser writing with a CO2 laser on a polyimide film at ambient conditions. Its characterization was analyzed by Raman, Fourier-transform infrared spectroscopy, field-emission scanning microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetric techniques. Linear response, the limit of detection, and sensitivity to the HXA were enhanced with the values of the range from 1.5 to 150, 0.14 µM, and 6.6 µA μM−1 cm−2, respectively. Effective resistance to common physiological interferences (such as uric acid, ascorbic acid, dopamine, glucose, and xanthine) was indicated, and additionally, the determination of HXA concentration in real samples with good selectivity is attributed to the synergistic effects between ZnO nanoparticles and fPGE. Therefore, the ZnO/fPGE has provided a favorable electrical environment for developing high-performance electrochemical biosensors to determine hypoxanthine in pork meat.

Enhancing Electrochemical Non-Enzymatic Dopamine Sensing Based on Bimetallic Nickel/Cobalt Phosphide Nanosheets.

In this study, the successful synthesis of bimetallic nickel/cobalt phosphide nanosheets (Ni-Co-P NSs) via the hydrothermal method and the subsequent high-temperature phosphorization process were both confirmed. Ni-Co-P NSs exhibited excellent electrocatalytic activity for the electrochemical non-enzymatic DA sensing. The surface morphologies and physicochemical properties of Ni-Co-P NSs were characterized by atomic force microscopy (AFM), field-emission scanning (FESEM), field-emission transmission electron microscopy (FETEM), and X-ray diffraction (XRD). Further, the electrochemical performance was evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The metallic nature of phosphide and the synergistic effect of Ni/Co atoms in Ni-Co-P NSs provided abundant catalytic active sites for the electrochemical redox reaction of DA, which exhibited a remarkable consequence with a wide linear range from 0.3~50 μM, a high sensitivity of 2.033 µA µM-1 cm-2, a low limit of detection of 0.016 µM, and anti-interference ability. As a result, the proposed Ni-Co-P NSs can be considered an ideal electrode material for the electrochemical non-enzymatic DA sensing.

Presence of bicontinuous microemulsion-type domains and dielectrically inert interfacial water layers in lamellar gel-stabilized oil-in-water emulsions

HypothesisLamellar gels are widely formulated in household and cosmetic products because of their eminent ability to improve long-term stability of thermodynamically unstable oil-in-water emulsions. However, despite long study, how and why membrane internal structure and membrane-membrane interactions are modified by the presence of polar and nonpolar oils remains elusive. ExperimentsUsing small- and wide-angle X-ray scattering, dielectric spectroscopy, and field-emission transmission electron microscope, we investigate intermembrane interactions and water-mediated microscopic interfacial properties in lamellar gels and lamellar gel-stabilized oil-in-water emulsions based on cetyltrimethylammonium chloride and 1-hexadecanol. FindingsReducing membrane surface charge density enhances undulation fluctuation disorder, resulting in a crossover of dominant interactions from electrostatic double-layer repulsion to Helfrich interaction. Oil-emulsification induces similar structural impacts to the reduced 1-hexadecanol ratio, confirming preferential dissolution of higher-alcohol in oil phases. An emerging Teubner-Stray scattering component upon emulsification of nonpolar oil evidences that oil droplets and lamellar gels are indirectly connected via bicontinuous microemulsion-type domains. Dielectric spectra reveal strikingly small water permittivity in the lamellar gel and emulsion samples, which is quantitatively explained by a cumulative effect of a dielectrically inert interfacial thin water layer (<1nm) and a highly polarizable bulk-like water layer. This phenomenon appears to be intrinsic to diverse lamellar stack architectures.

Effects of tire‐derived pyrolytic carbon black and pyrolytic heavy oil on the curing and mechanical properties of styrene‐butadiene rubber composites

AbstractTo investigate the potential effect of the pyrolytic carbon black (CBp) and pyrolytic heavy oil (HO), we incorporated them into styrene‐butadiene rubber (SBR) as reinforcing filler and plasticizing agent, respectively. Since the industrial N330 CB's specific surface area and other specifications adhere to the CBp standard, it has been selected as a benchmark. To test HO's applicability, conventional (AO) was substituted with it. We experimented with the N330 and CBp in the 1/1 variant. We examined the impacts on the cure behavior, physical characteristics such as density and hardness, mechanical properties, abrasion resistance, dynamic mechanical performance, and thermal properties of the filled SBR composites. According to field emission (FESEM) and transmission electron microscopy (TEM) micrographs, the increased tensile and tear strength is due to N330 black's superior dispersion over CBp in the rubber matrix. Better dispersion in N330 type CB is also justified by lower tan δmax from the dynamic mechanical analysis (DMA) study. Utilizing HO changes the curing conditions since it comprises more sulfur, which accelerates the formation of sulfur–sulfur cross‐links. Increased tensile and tear strengths, as well as improved dispersion in the rubber matrix, have been seen with the combined use of N330 and CBp. Meanwhile, HO could function well in place of commercially available AOs.Highlights The impact of scrap tires on human health and the environment is explored. Recovered carbon black (CB) from waste tire mixed with styrene‐butadiene rubber in various ratios. Pyrolytic oil is also incorporated to check its reusability in tire formulation. Similar cure characteristics and mechanical strength were found in the composites. Replacement of the conventional CB is proposed with recovered black.

A three-dimensional image reflecting the dispersion state of ceramic platelets in solvent: Observation of montmorillonite dispersed in silica gel by synchrotron X-ray multiscale tomography

Visualizing montmorillonite (MMT) platy particles dispersed in silica gel was firstly demonstrated by synchrotron X-ray multiscale tomography. The silica sol-gel reaction proceeded with the preservation of MMT dispersibility in water, MeOH, and DMF mixture. The 3D image reconstructed using high-resolution X-ray computed (CT) images (i.e., nano-CT) displayed platy particles in the range of 0.5—2.5 μm, which matched that observed in the field-emission microscope image of powder MMT. In addition, some platy particles are assembled by contacting their edge and layered surfaces, suggesting the presence of a house-of-cards structure. Given a decrease in the distance by 30% between platy particles roughly estimated using a decrease in volume by 65% before and after silica gelation, a dispersion state formed by micrometer-sized platy particles did not essentially differ after silica gelation. Therefore, these results indicated that the 3D image of MMT platy particles in silica gel reflected the dispersion state of MMT particles in the solvent.

Pristine, Ni- and Zn-Doped CuSe Nanoparticles: An Antimicrobial, Antioxidant, and Cytotoxicity Study.

The strategy of chemical coprecipitation is implemented to synthesize nanoparticles of pristine CuSe, 5 and 10% Ni-doped CuSe, and 5 and 10% Zn-doped CuSe. All of the nanoparticles are found to be near stoichiometric by the evaluation of X-ray energy using electron dispersion spectra, and the elemental mapping shows uniform distribution. By X-ray diffraction examination, all of the nanoparticles are identified as being single-phase and having a hexagonal lattice structure. Field emission microscopy with electrons in both scanning and transmission modes affirmed the spherical configuration of the nanoparticles. The crystalline nature of the nanoparticles is confirmed by the presence of spot patterns observed in the selected area electron diffraction patterns. The observed d value matches well with the d value of the CuSe hexagonal (102) plane. Findings from dynamic light scattering reveal the size distribution of nanoparticles. The nanoparticle's stability is investigated by ζ potential measurements. Pristine and Ni-doped CuSe nanoparticles exhibit ζ potential values in the preliminary stability band of ±10 to ±30 mV, while Zn-doped nanoparticles feature moderate stability levels of ±30 to ±40 mV. The potent antimicrobial effects of synthesized nanoparticles are studied against Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter aerogenes, and Escherichia coli bacteria. The 2,2-diphenyl-1-picrylhydrazyl scavenging test is used to investigate the nanoparticle's antioxidant activities. The results showed the highest activity for control (Vitamin C) with an IC50 value of 43.6 μg/mL, while the lowest for Ni-doped CuSe nanoparticles with an IC50 value of 106.2 μg/mL. Brine shrimps are utilized for in vivo cytotoxicity evaluation of the synthesized nanoparticles, which demonstrates that 10% Ni- and 10% Zn-doped CuSe nanoparticles are more damaging on brine shrimp instead on other nanoparticles with a 100% mortality rate. The lung cancer cell line of human (A549) is used to investigate in vitro cytotoxicity. The results indicate that pristine CuSe nanoparticles are more effective in the context of cytotoxicity against the A549 cell lines, possessing an IC50 of 488 μg/mL. The particulars of the outcomes are explained in depth.

Biosynthesis of ZnO.Ag2O3 using aqueous extract of Haplophyllum obtusifolium: Characterization and cell toxicity activity against liver carcinoma cells

AbstractThe zinc oxide‐silver oxide nanocomposite (ZnO.Ag2O3 particles) was prepared by using an aqueous plant extract of Haplophyllum obtusifolium for the first time. Powder X‐ray diffraction (PXRD), Fourier transforms spectroscopy (FTIR), field emission microscopy (FESEM), energy dispersive X‐ray analysis (EDX), and transmission electron microscopy (TEM) were applied to analyze the structure, functional groups, morphology, and purity of the prepared nanocomposite. PXRD revealed the formulation of ZnO.Ag2O3 for the particles. The investigation of functional groups has demonstrated the presence of some carbonated impurities along with absorbed water in the composition of the ZnO.Ag2O3 nanocomposite. Morphologically, particles have formed a petal‐like shape with different sizes. The EDX analysis also confirmed the composition of the prepared sample and the presence of 4.78% silver in the formula. Additionally, the TEM analysis revealed spherical and rectangular shapes with a particle size of 80.43 ± 46.73 nm. Moreover, the ZnO.Ag2O3 particles were used against cancer cells, which has shown synthesized NCs have a toxic effect against liver cancer cells in a concentration and time‐dependent manner.

Divalent cation substitution impact on the properties of strontium aluminium hexaferrite (SrAl2Fe10O19)

The strontium aluminium hexaferrite was substituted with the divalent ions (Ba/Ca) with the chemical formula of Sr1-xMxAl2Fe10O19 (M = Ba, Ca; x = 0.1, 0.2), and all the samples were synthesized via sol-gel auto combustion method. The particles are shaped in a hexagonal structure with space group P63/mmc. The field-emission scanning microscopy revealed the platelet-like morphology of the particles. The magnetic studies disclosed the single-domain arrangement of particles and decent energy product value for all the samples (0.36–0.38 MG Oe), implying their potential application in permanent magnets. The declined value of the Dielectric constant at mega-range frequency suggests that the samples could be useful for microwave application.

A green approach for preparation of polyacrylic acid/starch incorporated with titanium dioxide nanocomposite as a biocompatible platform for curcumin delivery to breast cancer cells

Curcumin (Cur) is a polyphenolic hydrophobic molecule with several biological uses, including cancer therapy. However, its widespread use in cancer treatment faces limitations due to its low solubility in acidic and neutral conditions, rapid removal from the circulatory system, and poor bioavailability. In order to overcome these challenges, a biocompatible and pH-sensitive carrier nanoplatform was designed for the specific delivery of curcumin to breast cancer cells. This nanocomposite containing polyacrylic acid (PAA), starch, and titanium dioxide (TiO2) was synthesized with a specific morphology through the water-in-oil-in-water green emulsification strategy. The nanocomposite structure was confirmed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and field-emission scanning electrom microscopy (FE-SEM) imaging tests. The mean particle size of 151 nm for the PAA-Starch-TiO2 nanocomposite ensures specific entry into cancer cells and minimal damage to healthy cells. Loading efficiency (LE) and encapsulation efficiency (EE) for curcumin obtained 49.50 % and 87.25 %, which are desirable for a carrier nanoplatform. Compared to the physiological medium, the in-vitro release of curcumin was higher in the acidic conditions in all time intervals, which indicates the possibility of targeted drug release from the PAA-Starch-TiO2 nanocomposite around the tumor tissue. Furthermore, for better understanding of the release mechanism, the cumulative release data in both media were fitted with common mathematical kinetic models. Cytotoxicity tests against the MCF-7 cell line were performed using in vitro MTT and flow cytometry tests. The results showed that the PAA-Starch-TiO2 carrying Cur was more effective through increasing the bioavailability and controlled release of the drug compared to the free Cur. Also, the death of cancer cells in the presence of this nanocomposite compared to free Cur occurred mainly through the induction of apoptosis, which indicates the programmed death of cancer cells and the high efficiency of the designed nanocarrier.

The recrystallization, texture and mechanical behavior of hot rolled and annealed Mg-10Ho binary alloy

The recrystallization, texture, and mechanical properties of hot-rolled and hot-rolled + annealed Mg-10Ho (wt %) are investigated. Mg-10Ho binary alloy is first solution treated followed by multipass rolling at 420 °C for up to 50 % reduction and subsequently annealed at 400 °C for different times for up to 60 min. The microstructure of deformed and annealed samples was characterized using a field-emission secondary electron microscope (FESEM) and electron back-scattered diffraction (EBSD) and the mechanical properties were examined using hardness and tensile tests. The as-rolled microstructure contains fine dynamic recrystallized grains and different types of deformation twins. With increasing annealing time, a decrease in the hardness was observed, suggesting initiation of recovery and static recrystallization. After 10 min of annealing, an equiaxed, nearly fully recrystallized microstructure with a grain size of 14 µm and weaker basal texture was obtained. This annealed sample exhibits an ultimate tensile strength of 213 MPa, yield strength of 145 MPa, and ductility of ∼7 %. Such an optimum combination of strength and ductility is attributed to the combined effect of solid solution strengthening, grain refinement, and texture weakening. Additionally, the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model was used to understand the recrystallization kinetics of Mg-10Ho and compared it with that of Mg-10Y. Results indicate that the solute drag effect plays a dominant role in the faster recrystallization kinetics of Mg-10Ho alloy. Finally, the texture variation in Mg-10Ho and Mg-10Y is also explained based on the solute drag effect.

Field electron emission and field ion microscope images of layered material MoS2

Field emission microscopy and field ion microscopy (FEM and FIM) of two-dimensional layered material, MoS2, were carried out. MoS2 field emitters were prepared by mechanical peeling of a single crystal and by deposition of MoS2 suspension. FEM exhibited an array of elongated broad spots, and the corresponding FIM images presented patterns consisting of streaked spots and split spots (double spots), depending on electric voltages applied to the emitter. Since the probability of field ionization of imaging gas atoms (Ne gas was used in the present study) is governed by both field strength near surface atomic sites and accessible vacant electronic states, these patterns reflect the atomic site and/or spatial distribution of unoccupied electronic orbitals at the edges of MoS2 layers.

Study of Ni–Cr / CrN bilayer thin films resistor prepared by magnetron sputtering

In this study, we prepare bilayer Ni–Cr/CrN films. A Ni–Cr resistive thin film was prepared by DC sputtering from targets of Ni0.8-Cr0.2 casting alloy. A CrN protection thin film was prepared based on optimum sputtering conditions of the Ni–Cr film, which was made by DC and RF magnetron co-sputtering from targets of Ni0.8-Cr0.2 casting alloy and chromium. The electrical properties and microstructures of the resistive films at different annealing temperatures were investigated. The phase evolution, microstructural and composition of Ni–Cr and NiCr/CrN films were characterized by X-ray diffraction (XRD), field-emission transmission electron microscopy (HRTEM) and auger electron spectroscopy (AES). The results indicated that the resistivity of the bilayer Ni–Cr/CrN films is higher than Ni–Cr films. When the annealing temperature was set to 300 °C, the bilayer Ni–Cr/CrN films exhibited a resistivity ∼303 μΩ cm with the smallest temperature coefficient of resistance (TCR) of −3 ppm/°C. However, the Ni–Cr films that annealed at 300 °C showed a resistivity of ∼210 μΩ cm, with a TCR of 13 ppm/°C. In addition, the TCR and resistivity variation rate of CrN protective coating layer on the Ni–Cr films after high temperature testing at 150 °C up to 100 h was done. The results show that the average change rate of the TCR for bilayer Ni–Cr/CrN films is lower than single Ni–Cr films.

The role of sulphur in the early production of copper red stained glass

Little is known about the production of ruby red copper stained glasses from the Medieval and Renaissance periods apart from the fact that the colour is due to the presence of small metallic copper nanoparticles and that tin, the most common reducing agent used in copper red glass production since the 19th century, is not present. In fact, very few workshops in Europe were able to make red glass in historical times, and they kept it secret, so very little is known about how it was obtained. These workshops exported the red glass throughout Europe. Recently, the presence of copper sulphide particles and the data obtained in the replication red glass following historical recipes suggested that sulphur might be the key ingredient in this process.Here, a collection of historical red glasses from these periods has been analysed using a combination of microanalytical techniques; Electron Microprobe (EM) and Field Emission and Scanning Electron Microscopy (FESEM) to verify the chemical composition and nanostructure of the glasses, Synchrotron radiation micro-X-Ray Diffraction (micro-XRD) to establish the nature of the nanocrystalline precipitates, and S, Cu and Fe K-edge micro-X-Ray Absorption Spectroscopy (micro-XAS) to determine the speciation. The data obtained show that the oxidation of S2− into S6+ in the glass is responsible for the precipitation of copper nanoparticles. The development of a sulphide-silicate partition and the presence of Fe3+ in the melt give rise to the precipitation of the high-pressure tetragonal polymorph of chalcocite (Cu2S). Differences between the Medieval and Renaissance red glass are determined.