Dispersive X-ray Analysis Electron Research Articles

Experimental and theoretical properties of S–Mo–Co–S clusters

In this work we propose that certain structures found in real commercial catalysts may be related to low dimensional structures. These structures are S–Mo–S and S–Mo–Co–S nanowires which were characterized by High Resolution Scanning Transmission Electron Microscopy (HR-STEM), Electron Diffraction (ED) and Electron Dispersive X-ray analysis (STEM-EDAX). Furthermore, a structural model was constructed with the one dimensional structures in order as to investigate their electronic properties. Energy band analysis on the samples yield indication about the semi metallic behavior, while a careful analysis to the partial Density of States (PDOS) in the vicinity of the Fermi level, provided indication for the existence of strong hybridization between S p- with Mo d- and Co d- and p-orbitals for the samples enunciated formerly. In addition, a very important issue to be mentioned is that in the construction of the 1T-S–Mo–Co–S nanowires, the Co and Mo atoms are not in their pure trigonal prismatic environment as compared to the bulk 2H-MoS 2. This issue could be deleterious for future catalytic applications.

Electrical transport mechanism in plasma polymerized 2, 6, diethylaniline thin films

Plasma polymerized 2, 6, diethylaniline (PPDEA) thin films were deposited at room temperature on to glass substrates by a capacitively coupled parallel plate glow discharge reactor. The surface of the PPDEA thin films has been found uniform and pinhole free from the scanning electron micrographs. The observation by electron dispersive X-ray analysis indicates the presence of carbon, nitrogen and oxygen in the PPDEA thin films. The current density–voltage characteristics of aluminum (Al)/PPDEA/Al structure of different film thicknesses have been studied at different temperatures. In the low voltage region, the conduction current obeys Ohm's law while the charge transport phenomenon appears to be Schottky type in the higher voltage region. The temperature dependence of the current density for different bias voltages was also investigated which confirms the possibility of Schottky emission in PPDEA thin films as well.

Composite Ni–Co–fly ash coatings on 5083 aluminium alloy

Ni–Co–fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni–Co–fly ash coatings were found to consist of a crystalline Ni–Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni–Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni–Co–fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

Physiochemical properties of mixed oxides of iron and silicon

The work presented here deals with the synthesis and characterization of silica, iron hydroxide and their mixed oxides M 1 (0.25 M SiO 2:0.75 M Fe(OH) 3), M 2 (0.50 M SiO 2:0.50 M Fe(OH) 3), and M 3 (0.75 M SiO 2:0.25 M Fe(OH) 3) of various molar ratios. Fe(OH) 3 was prepared by precipitation while the rest of the solids were synthesized by the sol–gel method. For the synthesis of mixed oxides, Fe(NO 3) 2.12H 2O and Na 2SiO 3 were employed as precursors for Fe(OH) 3 and silica respectively. The surface charge and structure of the materials were investigated by X-ray diffraction (XRD), surface area analysis (SAA), thermal analysis (TG-DTG), scanning electron microscopy (SEM), electron dispersive X-ray (EDX) analysis, Fourier transform-infrared (FT-IR) spectroscopy and the point of zero charge (PZC) was determined by the salt addition method and by measuring the ζ-potential versus pH. The results obtained from the nitrogen adsorption–desorption isotherms reveal that the sol–gel method is a suitable route for synthesizing materials of high surface area. Moreover, the values of the PZC determined by salt addition method and by electrokinetic potential are found to be close to each other.

A simple CdS nanoparticles cascading approach for boosting N3 dye/ZnO nanoplates DSSCs overall performance

Enhanced photosensitization in presence of CdS nanoparticles is achieved in electrochemically deposited ZnO nanoplates and N3 loaded dye-sensitized solar cells. Chemically embedded CdS nanoparticles act as a sandwiching layer between ZnO nanoplates and dye molecules by overcoming current limiting serious Zn 2+/dye insulating complex formation and CdS photo-corrosion issues. The X-ray diffraction and the scanning electron microscopy confirm the ZnO with vertically aligned nanoplates, perpendicular to the substrate surface. Amorphous CdS is monitored using electron dispersive X-ray analysis. The low and high resolution transmission electron microscope images confirm the presence of CdS nanoparticles over ZnO nanoplates which later is supported by an increase in optical absorbance and shift in band edge. About 400% increase in solar conversion efficiency with this cascade arrangement is achieved when compared with without CdS which could be fascinating while designing solid state solar cells in presence of suitable p-type layer.

Physicochemistry of dispersions of HgO, HgS and ‘Makardhwaj’ (an Ayurvedic medicine) prepared in micelle and microemulsion templates

Micelle and microemulsion templates are used to prepare dispersions of HgO and HgS. The prepared HgO dispersions are obtained in four different colors viz. yellow, orange, red, and bluish-white, though the bulk HgO shows only two colors, red and yellow. The synthesized HgS particles in micellar solutions appear faintly grayish. These dispersions of HgO and HgS show characteristic spectral features. They are characterized by spectral, X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. The products formed in water/CTAB + n-butanol/n-heptane microemulsion (CTAB being cetyltrimethylammonium bromide) evidence characteristic differences from that prepared in micellar media. Both HgO and HgS preparations show low semiconductivity. Their band gaps range between 3.6 and 5.71 eV. HgO dispersions prepared in Triton X-100 (TX-100) micellar solution are spherical (∼150 nm diameter) whereas that prepared in Tween-20 (TW-20) medium are prolate type (major axis ∼300 nm). In CTAB micellar solution tubes of diameter 150 nm are formed. The HgS preparation in the aforesaid w/o microemulsion appears grayish and transparent. The shapes of the particles are spherical with a size in the range 10–25 nm as found from the TEM study. ‘Makardhwaj’, an Ayurvedic medicine (comprising of HgS, Au and Au 2S), also shows characteristic spectral features in micellar and microemulsion media. The grinded dispersed ‘Makardhwaj’ particles are nearly spherical with average size of 10 nm, and evidence the presence of Au, S and Hg in the ratio 1:3.4:30 from electron dispersive X-ray analysis (EDAX) measurements. The results suggest that HgS dispersions fall well within the conventional nano-domain (100 nm) whereas HgO dispersions are moderately out of the domain.

Wetting of Cu by Bi–Ag based alloys with Sn and Zn additions

Contact angles on copper substrate of Bi–Ag–Sn and Bi–Ag–Zn ternary alloys containing 3, 6, and 9 at.% of Sn and Zn, respectively, were studied with the sessile drop method. Wetting tests were carried out at 573 and 603 K with or without the use of a flux. Without the flux, the examined alloys do not wet copper, i.e., the observed contact angles are higher than 90°. However, in the presence of the flux wetting of copper is observed. In the case of alloys with Sn, the contact angles decrease with increasing content of Sn, while in the case of alloys with Zn no such tendency is observed. Solidified solder–substrate couples were cross-sectioned and examined with scanning electron microscopy coupled with electron dispersive X-ray analysis.

Gastroretentive floating sterculia–alginate beads for use in antiulcer drug delivery

To improve the bioavailability and therapeutic efficacy of the drugs used for the diseases associated with the stomach, the retention of drug delivery systems in the stomach for longer time is requred. Therefore, in the present study, an attempt has been made to synthesize gastro-retentive floating drug delivery system by simultaneously ionotropic gelation of alginate and sterculia gum by using CaCl 2 as crosslinker. The beads thus formed have been characterized by scanning electron micrographs (SEMs), electron dispersion X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR) analysis. The swelling of beads has been carried out as a function of various reaction parameters and pH of the swelling media. In addition, in vitro release dynamics of anti-ulcer model drug pantoprazole from drug loaded beads in different release media has been carried out for the evaluation of the drug release mechanism and diffusion coefficients. Release of drug from beads occurred through Fickian type diffusion mechanism.

江戸時代後期に製造された管打銃の金属組織と非金属介在物

The metallurgical microstructure and nonmetallic inclusions in the steel barrel of a Japanese percussion lock gun fabricated in the late Edo period have been investigated. The purpose of this work is to obtain metallographic data of the Japanese percussion lock gun, and to clarify the manufacturing technique and raw material of the barrel. Test pieces are cut from the center and the muzzle of the barrel. The carbon concentration is determined by chemical analysis. The microstructure is observed using an optical microscope and a scanning electron microscope (SEM). The concentration of nonmetallic inclusions is obtained by electron dispersive X-ray analysis (EDS). The carbon concentration is 0.003~0.2 mass% for the center of the barrel and 0.028~0.2 mass% for the muzzle of the barrel. The distribution of the nonmetallic inclusions in the steel shows that the barrel is fabricated from a single steel sheet. Nonmetallic inclusions in the center of the barrel are of a plural phase consisting of FeO, Fe2SiO4 and calcium-and phosphorus-rich matrix oxide. Nonmetallic inclusions in the muzzle of the barrel are classified into two types: a plural phase consisting of FeO and the matrix containing Fe-Si-O grains and glass, and a single phase of glass. The difference in the metallurgical microstructure and nonmetallic inclusions between the center steel and the muzzle steel shows that the barrel is made of different carbon-content steels. Since Ti is detected from the nonmetallic inclusions, it is thought that Japanese iron sand is used as the raw steel to fabricate the barrel.

Imidazolium modified carbon nanohorns: switchable solubility and stabilization of metal nanoparticles

Imidazolium-modified carbon nanohorn-based hybrid materials have been prepared and characterized by complementary spectroscopic, thermal and microscopy techniques, while the counter-anion of the positively charged imidazolium fragment has been identified by electron dispersive X-ray analysis. In particular, oxidized carbon nanohorns, activated upon reaction with oxalyl chloride, have been initially covalently coupled with (3-aminopropyl)imidazole, while further reaction with n-butyl bromide resulted to the formation of the N-n-butylimidazolium-modified carbon nanohorns as a stable dispersion in aqueous media. Moreover, the bromide anion of the imidazolium-based hybrid material, can be exchanged by [PF6−], [ClO4−] and [BF4−] anions upon treatment with the corresponding salts, resulting on switching of the solubility of the hybrid material from aqueous to organic solvents. On the other hand, when the [PF6−] N-n-butylimidazolium-modified carbon nanohorn hybrid material was treated with Na2SO4, NaNO3 or NaCl, the solubility of the as prepared hybrid materials was switched to aqueous media again. Thus, the nature of the counter-anion on the imidazolium-modified carbon nanohorns modulates the wettability of the material (i.e. switchable hydrophilic vs. lipophilic counter-anion and vice versa). In addition, the newly prepared hybrid materials have been employed as effective stabilizers to grow platinum and palladium nanoparticles, while their presence has been proved both by HR-TEM and EDX analysis.

高麗遊児書像鏡の金属組織と不純物

The microstructure and impurities in a Korai (10~14c) Bronze Mirror illustrated with four boys with musical instruments has been investigated. Transmission electron microscope, X-ray diffractometer, scanning electron microscope, and electron dispersive X-ray analyses are used to determine the structure of the specimen. The composition of the specimen is Cu-9.7 mass%Pb-10 mass%Sn-0.6 mass%S, and Ag and Si are detected as trace elements. The microstructure of the Korai bronze mirror consists of αCu, αCu41Sn11, Pb, and a phase containing S. It is clarified that the phase containing S is Cu2S (JSPDS 33-0490) by electron diffraction pattern analysis. It is thought that Cu2S is a residue of the intermediate product, Cu2S, in the refining of the copper ore, chalcopyrite (CuFeS2). Therefore, the copper ore has not been completely refined. Fine Pb particles are observed in the Cu2S grains, and fine PbS crystals also exist between Pb and Cu2S.

江戸時代に製造された火縄銃の非金属介在物の組成と構造

The composition and microstructure of nonmetallic inclusions of a Japanese matchlock gun, called Hinawa-ju in Japanese, fabricated in the Edo period have been investigated. The purpose of this work is to study the composition and microstructure of nonmetallic inclusions of the barrel and to obtain modern materials-science data of the raw materials of the Japanese matchlock gun. Test pieces are cut from the center and the male screw of the barrel. Nonmetallic inclusions of the barrel are observed using an optical microscope and scanning electron microscope (SEM). The small-area concentration of a nonmetallic inclusion is obtained by electron dispersive X-ray analysis (EDS). The electron backscattering pattern (EBSP) is analyzed using an ultrahigh-resolution scanning electron microscope. Fe, Si, Al, Ca, K, Mg, P, Na and Ti are detected from nonmetallic inclusions of the center of the barrel. As Ti is detected from many parts of the nonmetallic inclusions, iron sand is inferred to have been used as the raw iron material of the barrel. Nonmetallic inclusions of the center of the barrel are classified into two groups. One is a plural phase and is consisted of FeO (wustite), Fe-Si-O grains, multi-element grains and glass-rich matrix oxide. The other type is a single phase of aluminum silicate glass. Fe, Si, Al, Ti, Ca, Mg, K, Na, P, Mn and S are detected from nonmetallic inclusions of the male screw of the barrel. As Ti is detected from many parts of the nonmetallic inclusions, iron sand is again thought to have been used as the raw iron material of the male screw. Nonmetallic inclusions of the male screw are of the plural phase and consist of Fe-Ti-O grains, aluminum silicate oxide and aluminum silicate glass matrix.

高麗青銅貨：海東通寶(ヘドントンボ)の金属組織と不純物の微細構造

The microstructure of the bronze coin, Headongtongbo, circulated around 1097 and fabricated in the Korai period (10~14th centuries) has been investigated. The coin is 23.4 mm in diameter and 1.7 mm in thickness with weight of 4.75 g. Transmission electron microscope, X-ray diffraction, scanning electron microscope, and electron dispersive X-ray analyses are used to determine the structure of the specimen. The composition of the specimen is Cu-6.1 mass%Sn-1.4 mass%Pb-0.5 mass%S. αCu, Pb and Cu2S grains are observed using an optical microscope. The Cu2S phase has been observed in a Korai bronze mirror, as reported in the previous paper. The αCu phase shows a recrystallized polygonal structure. In some part of the αCu grains, twins and fine twinlike lines are observed. Cu2S particles are dispersed in αCu grains and the grain boundary. In αCu grains near the surface, grain boundaries and the twin boundary are corroded preferentially. The Cu2S grains retain their original shape and remain in the corroded layer. αCu corrodes from Cu2O to CuO, and then to Cu2CO3(OH)2.

Dipolar Driven Spontaneous Self Assembly of Superparamagnetic Co Nanoparticles into Micrometric Rice-Grain like Structures

Superparamagnetic single crystal single domain Co nanoparticles of 6 nm in diameter evaporated onto highly pyrolytic oriented graphite spontaneously self-assemble into super structures with an elongated shape. These structures have been studied by optical and scanning electron microscopies, atomic and magnetic force microscopy, electron dispersive X-ray analysis, and SQUID magnetometry. We propose that the weak dipolar interactions between superparamagnetic dipoles of the cobalt nanoparticles are responsible for the formation of these structures when the dipolar magnetic interactions are strong enough to influence the general process of self-assembly dominated by van der Waals forces between neighboring nanoparticles and between nanoparticles and the substrate during evaporation of the solvent.

Evaluation of corrosion behavior of surface modified Ti–6Al–4V ELI alloy in hanks solution

The passive film behavior of Ti–6Al–4V ELI (Extra Low Interstitial) alloy after a chemical treatment followed by a thermal treatment was morphologically and electrochemically characterized. The surface morphological studies were carried out using scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDAX), and Fourier Transformed-Infra Red (FT-IR) analysis to investigate the nucleation and growth of apatite on the chemically and thermally treated Ti–6Al–4V ELI alloy immersed for different durations in Hanks solution. Polarization and impedance spectroscopic (EIS) measurements were carried out in Hanks solution and the electrical parameters were obtained for the passive film using a non-linear least square fitting (NLLS) method.

Composition–constitution–morphology relationship of Al 2O 3 thin films deposited by plasma assisted chemical vapor deposition

We have studied the correlation between the chemical composition, constitution and morphology of Al 2O 3 using experimental and theoretical means. Combining scanning electron microscopy, transmission electron microscopy, electron dispersive X-ray analysis and ab initio calculations, we have investigated the formation of pores. Desorption measurements show chlorine release from γ- and α-alumina films. Based on ab initio calculations, we have established that Cl can be incorporated in both γ- and α-alumina. Furthermore, two Cl atoms are likely to agglomerate since the total energy is reduced, compared to an unagglomerated configuration. We propose that Cl agglomeration is the first step towards Cl 2 formation and subsequent precipitation and bubble formation. It can be learned that the Cl incorporation has to be minimized during growth of dense alumina coatings.

Quality Assessment and Quality Control of Deep Soil Mixing Construction for Stabilizing Expansive Subsoils

This paper presents the process and results of a quality management program performed during and immediately after the construction of two deep soil mixing (DSM) test sections. The quality management program consisted of laboratory, in situ, and mineralogical tests to address the effectiveness of the treatment during and after construction. In situ investigations including the down-hole seismic and spectral analysis of surface waves (SASW) test methods were performed to evaluate the degree of improvement achieved through the measurement of compression and shear-wave velocities of the columns and surrounding soils. Scanning electron microscopy and electron dispersive x-ray analysis were performed on raw, laboratory treated and field-treated specimens for qualitative understanding of the degree of mixing achieved in the field and the compounds formed at particle level during stabilization, respectively. Laboratory tests results on field cores indicated that both field stiffness and strength are about 20 to 40% less than the corresponding laboratory prepared soil samples. The down-hole seismic and SASW tests showed considerable improvement in stiffness in and around the DSM columns. Mineralogical studies indicated the formation of silica and alumina hydrates along with interwoven structure of lime-cement treated clay particles in both laboratory and field specimens, suggesting adequate mixing of the soil and binder in both environments.

Composite zinc-fly ash coating on mild steel

Zinc-fly ash composite coatings were deposited on mild steel substrates with the help of electrodeposition technique. Metallographic and chemical characterization of the produced composite coatings was performed with the aid of Scanning Electron Microscopy (SEM) and Electron Dispersive X-ray Analysis (EDX). The corrosion behaviour of the composite coated mild steel substrate was studied in a 0.3 M NaCl solution (pH = 5.5) by means of anodic polarization curves. The wear of the zinc-fly ash coating was also investigated by using a pin-on-disk apparatus. The composite coating exhibited increased wear resistance, compared to the pure zinc coating and the mild steel substrate. The adhesion strength between the zinc-fly ash coating and the mild steel substrate was examined with a scratch testing apparatus. The adhesion strength between zinc-fly ash composite coating and the mild steel substrate was found to be higher than that of the pure zinc coating to mild steel.

Superhydrophobic surfaces via electroless displacement of nanometric Cu layers by Ag +

This paper explores the possibility of making hydrophobic and superhydrophobic surfaces from electroless displacement of Cu by Ag +, in the case where Cu oxidation is limited owing to Cu layers of nanometric thicknesses. The morphology of the Ag layers is studied by scanning electron microscopy for Cu thicknesses between 10 and 80 nm. The mapping of the elemental content of the layers by electron dispersive X-ray analysis also has been used to clarify the particle growing by diffusion limited aggregation. It is shown that the average size and the shape complexity of the Ag particles increase with the Cu thickness. The addition of dimethyl sulfoxide in the Ag + aqueous solution improves the surface homogeneity, increases the particle density and decreases their sizes. The wetting behaviour of the surfaces, after grafting with octadecanethiol, has been studied from measurements of the contact angles of a drop of water. According to the thickness of the initial Cu layer and the morphology of the Ag layer, contact angles range between 110° and 154°. Superhydrophobic surfaces are obtained from 80 nm thick Cu layers.

Synthesis, Electrocatalytic and Anomalous IR Properties of Hollow CoPt Chainlike Nanomaterials

Hollow CoPt chainlike nanomaterials were synthesized by a galvanic displacement reaction. The morphology, structure, and composition of the nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron dispersive X-ray (EDX) analysis. It has found that the hollow CoPt chainlike nanoparticles supported on glassy carbon substrate (CoPt/GC) exhibited enhanced electrocatalytic activity toward methanol oxidation in comparison with commercial Pt/C catalyst (Johnson-Matthey, 20 wt% Pt). The studies demonstrated also that the hollow CoPt chainlike nanomaterials possess a superior electrocatalytic property for CO oxidation than that of Pt/C and bulk Pt. The IR properties of the CoPt nanomaterials were investigated by in situ FTIR reflection spectroscopy employing CO adsorption as probe reaction. It has revealed that the hollow CoPt chainlike nanomaterials present abnormal infrared effects (AIREs).