Energy Dispersive X-ray Analysis Data Research Articles

The influence of heating conditions of the samples of nickel nanopowders on the modes of their interactions with the air

In the present work, compact samples of pyrophoric nickel nanopowders with an average particle size of 55 nm obtained by the method of chemical metallurgy were investigated. The possibility of passivation of compact samples 3 mm in diameter made of nickel pyrophoric nanopowders in the air is experimentally shown for the first time. The time of complete passivation is only 3–5 s for a relative sample density 0.4–0.5. According to X-ray phase analysis, only Ni phase was observed in passivated samples. It was found that passivated samples maintain thermal stability in the air at slow (< 10 °C/s) heating to ~ 200 °C; it is an important parameter for fire safety at handling of nanopowders. The analysis of passivated samples by the SEM method showed no traces of sintering of nickel nanoparticles, even after testing for thermal stability. The uniform distribution of oxygen within passivated samples according to energy dispersive X-ray analysis data indicates the volumic nature of the interaction of samples with the air during passivation. For the passivated samples, critical heating conditions were determined, under which self-ignition occurs.

Effect of Fe-In co-doping on microstructural, optical, electrical and LPG response properties of spray pyrolytic ZnO thin films

Abstract This work investigates the microstructure, optical absorption, electrical resistivity and LPG (Liquefied Petroleum Gas) response of ZnO thin film with the change in relative doping concentrations of In and Fe in the host lattice. All the films retain polycrystalline nature with hexagonal wurtzite unit cell structure. Scanning electron microscopic study reveals that regular spherical shaped nanoparticles are formed in undoped ZnO, but a compact surface morphology has obtained in case of 3 at.% In doped ZnO (IZO) thin films owing to the reduction in particle size. In the case of 1 at.% Fe co-doping in IZO, nano-flakes are formed. However, at higher Fe doping concentration, this typical particle morphology gradually changes to spherical shapes again. By comparing the energy dispersive X-ray analysis data, the formation of flakes type nanostructures is attributed to the presence of excess oxygen in the sample and it dominates the thermally activated conductivity phenomenon in the low temperature range. Fe-In co-doping results low optical transmittance and reduction in the band gap of ZnO. It also lowers the conductivity in IZO thin film. IZO thin film samples exhibit better LPG response than ZnO and Fe-In co-doped ZnO samples owing to its smaller particle size.

Radiation Defects in Aluminum Nitride under Irradiation with Low-Energy C2+ Ions

The radiation resistance of ceramic materials based on aluminum nitride have been studied. The irradiation has been performed at a temperature of 300 K using 40-keV C2+ ions with a fluence varied from 1014 to 1015 ion/cm2. The dependences of crystallographic characteristics and strength properties on the ion fluence have been determined on the basis of X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis data. It has been found that the irradiation results in the formation of an impurity phase Al4C3 in the surface layer, which leads to an increase in the lattice parameters. This finding indicates the implantation of C2+ ions and the formation of the interstitial phase in the structure.

Bone marrow derived mesenchymal stem cell response to the RF magnetron sputter deposited hydroxyapatite coating on AZ91 magnesium alloy

The aim of this study was to investigate adhesion of bone marrow stromal cells (BMSCs) and in vitro degradation of hydroxyapatite (HA) coatings deposited on the surface of magnesium alloy (AZ91). The uniform and pore-free HA coating was successfully obtained via RF magnetron sputter deposition at the substrate bias of −25 and substrate bias of −100 V followed by post-deposition annealing. The structural features of the HA coating have been characterized and biological performance of the HA coating has been examined via in vitro test. The X-ray diffraction and Energy dispersive X-ray analysis data revealed that the phase and elemental composition of the deposited HA coatings were similar, but the surface roughness and morphology were influenced by the substrate bias voltage. The coating deposited at −25 V consists of multiple grain-boundaries. In contrast, no grain boundary but rather flat surface was observed for the sample deposited at −100 V. Atomic force microscopy (AFM) was used to obtain topographic images of the obtained coatings and quantitative assessment of the surface roughness. The roughness parameters of the deposited coatings were found to display nanometer scale surface roughness (Sa and Sq) from 92 to 130 nm over areas of 5 × 5 μm2. The in vitro direct culture experiment showed that the HA coating deposited at the substrate bias of −100 V significantly reduced the release of Mg ions in post-culture media and revealed higher BMSCs adhesion density than that on the HA coating deposited at the bias of −25 V and the uncoated AZ91 alloy. Thus, this study demonstrated that the negative pulse substrate bias applied for HA coating deposition allows to improve the surface features of the AZ91 magnesium alloy and enhance BMSCs adhesion in vitro.

Nanohematite from Ferruginous Quartzites of Kursk Magnetic Anomaly According to Transmission Electron Microscopy Data

Transmission electron microscopy study of ferruginous quartzite (jaspilites) from the Lebedinsky field of Kursk magnetic anomaly has revealed for the first time hematite nanoformations (about 10 nm in size), sp. gr. R3, which coexist with hematite, sp. gr. R3c, in the same crystallographic orientation or manifest themselves as individual nanoinclusions in the substrate of poorly crystallized magnetite. On the assumption that, in correspondence with the energy-dispersive X-ray analysis data, octahedral sites in the hematite structure can be occupied by only Fe cations, several structural models are proposed explain the hematite symmetry lowering to R3.

Estimation of the thickness of graphite nanofilm on a silicon substrate by using energy dispersive X-ray analysis data

Energy-dispersive X-ray spectroscopy is applied to analyze composition and thickness of graphite nanofilm on a substrate. We estimate the thickness of graphite nanofilm on a silicon substrate using a simple equation proposed in this work. The equation is based on data of the energy-dispersive microanalysis and not contains fitting parameters. The condition of applicability of the formula is a low value of the electron acceleration voltage at which the depth of electron beam penetration not exceeds a silicon oxide layer thickness. The number of graphite nanofilm layers estimated from the calculated thickness is reasonably confirmed by Raman spectroscopy data. It is shown, that the number of graphite nanofilm layers can be determined by carbon atomic content in at %.

Effect of a magnetron-sputtered ZrSiN/ZrO2 film on the bond strength of commercially pure titanium to porcelain

The excessively thick and nonadherent titanium oxide layer formed during the porcelain sintering process can cause bonding problems between titanium and porcelain. The purpose of this study was to evaluate the effect of a magnetron-sputtered ZrSiN/ZrO2 composite film on the bond strength of commercially pure titanium (CP Ti) to porcelain. Sixty-eight cast titanium specimens were prepared according to the ISO 9693 standard and then divided into 2 coated and 2 noncoated groups (n=17). The ZrSiN/ZrO2 composite film was deposited on specimens of the 2 coated groups by magnetron sputtering. A low-fusing porcelain was applied on 1 coated group and 1 noncoated group. A surface profilometer, surface roughness tester, energy-dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), and x-ray diffraction (XRD) were used to examine the characteristics of the film and the interfacial properties, while the bond strength of titanium-porcelain specimens was analyzed with the 3-point bend test. The results were analyzed with an independent samples t test (α=.05). The mean bond strength of ZrSiN/ZrO2-coated CP Ti to porcelain (43.67 ±2.08 MPa) was significantly higher than that of the noncoated group (35.44 ±3.56 MPa). A generally cohesive failure mode was observed in the coated group, but the failure mode in the noncoated group was adhesive. EDS data showed that the ZrSiN/ZrO2 film effectively prevented the intrusion of oxygen into the Ti substrate. The data suggested that the magnetron-sputtered ZrSiN/ZrO2 film could significantly improve the bond strength of CP Ti to porcelain and this may have clinical significance.

Structural, electrical, and decorative properties of sputtered zirconium thin films during post-annealing process

Zirconium thin films were deposited on a glass substrate using direct current magnetron sputtering technique and then post-annealed at different temperatures (100°C to 500°C in steps of 100°C) in an oxygen constant flow. The dependence of crystallographic structure, surface morphology, chemical composition, and electrical and decorative properties of the films on the annealing temperature was investigated. X-ray diffraction showed different phases of zirconium oxide at different annealing temperatures. It is observed that crystallite size and nanostrain increase with annealing temperature. Atomic force microscopy results showed granular structure in all samples, while both grain size and film surface roughness increased with the annealing temperature. Energy dispersive X-ray analysis data showed that the ratio of O/Zr was approximately 1.6, 1.7, 1.9, 2.1, and 2.2 at annealing temperatures of 100°C, 200°C, 300°C, 400°C, and 500°C, respectively. The annealed films at higher temperatures (400°C and 500°C) were transparent, while annealed films at lower temperatures (100°C to 300°C) were grey and brown, respectively. The variation of electrical resistance of samples with applied voltage was approximately constant, while it increased with annealing temperature.

PdAu membranes supported on top of vacuum-assisted ZrO2-modified porous stainless steel substrates

To enable the formation of defect-free PdAu composites by electroless plating, the vacuum-assisted ZrO2-modified method was optimized on top of porous stainless steel disks. Both the ZrO2-modified supports and the PdAu synthesized membranes were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), EDS (energy dispersive X-ray analysis) and XPS (X-ray photoelectron spectroscopy). SEM cross-section results showed that dense, continuous, defect-free PdAu films were deposited on top of the ZrO2-modified PSS disks, and the EDS data indicated that no significant concentration gradient was present on the thickness. At 400°C and 100kPa, the pure hydrogen permeation flux for a 10μm thick PdAu membrane was about 0.14mols−1m−2 and the H2/N2 ideal selectivity was higher than 10,000.

A TEM study of nanoparticles in lustre glazes

Transmission electron microscopy (TEM) has been used to investigate the nanoscale morphology of some contemporary lustre glazes. High-resolution TEM, electron energy-loss spectroscopy and energy-dispersive X-ray analysis data imply that two kinds of nanoparticles are present in the lustre layer, namely metallic Ag and metallic Cu particles. Moreover, these particles appear separated in the material. The dense top layer consists of Ag particles and the particles occurring below this upper layer are metallic Cu. A depth profile of the sizes of the nanoparticles with respect to their penetration depths has been drawn. The particle sizes are mainly situated in the range of 5 nm to 15 nm, though smaller and larger particles occur frequently.

Structure and magnetic properties of rf thermally plasma synthesized Mn and Mn–Zn ferrite nanoparticles

Plasma synthesis has previously been shown to be a viable route to producing nanocrystalline magnetite and Ni ferrite nanoparticles. In this work nanocrystalline powders of Mn and Mn–Zn ferrites have been synthesized using a 50 kW–3 MHz rf (radio frequency) induction plasma torch. We investigate these materials for soft magnetic applications. High-energy ball milled Mn + Fe powders and (Mn+Zn) +Fe powders (&amp;lt;10 μm) in the stoichiometric ratio of 1:2 were used as precursors for the ferrite synthesis. Compressed air was used in the oxygen source for oxidation of metal species in the plasma. X-ray diffraction patterns for the plasma-torched Mn ferrite and MnZn ferrite powders were indexed to the spinel ferrite crystal structure. An average grain size of ∼20 nm was determined from Scherrer analysis confirmed by transmission electron microscopy studies. The particles also exhibited faceted polygonal growth forms with the associated truncated cuboctahedral shapes. Room-temperature vibrating sample magnetometer measurements of the hysteretic response revealed saturation magnetization Ms and coercivity Hc of Mn ferrite are 23.65 emu/g and 20 Oe, respectively. The Néel temperatures of Mn ferrite powders before and after annealing (500 °C, 30 min) were determined to be 200 and 360 °C, respectively. Inductively coupled plasma chemical analysis and energy dispersive x-ray analysis data on the plasma-torched powders indicated deviations in the Mn or Zn contents than the ideal stoichiometry. MnZn ferrite was observed to have a Néel temperature increased by almost 400 °C as compared with as-synthesized Mn ferrite but with a larger coercivity of ∼35 Oe.

The corrosion of carbon steel in a chloride environment due to periodic voltage modulation: Part II

The influence of negative half-cycle rectified and full-wave sinusoidal potentials superimposed at two DC levels on carbon steel (1018) in 3.33% NaCl solution under nitrogen purge on materials degradation behavior was investigated. The results obtained indicate that the metal dissolution rate increases with the peak potential for the two signals applied at 60 Hz and a fixed potential of −580 mV(SCE). The dissolution rate was found to be the highest for the full-wave sinusoidal and the lowest for the negative half-cycle rectified signals. The metal dissolution rate decreases for the negative half-cycle rectified, but increases albeit moderately for the full-wave sinusoidal potential with the peak potential for experiments conducted at a potential of −780 mV(SCE). Generally, the current was found not to decrease with time except for the experiment involving application of signals at a more cathodic potential of −780 mV(SCE). Micrographs show that the samples experienced extensive pitting. Energy dispersive X-ray analysis data show that the chloride content in corrosion products increases as the metal dissolution rate increases. The data indicate that the arithmetic sum of materials degradation rates for the positive half-cycle and negative half-cycle rectified potentials approximately equals the rate for the full-wave sinusoidal potential. The data obtained strongly indicate that although the corrosion is enhanced by the application of alternating voltages, the rate is generally determined by the DC potential maintained at the anode; the more anodic the potential, the higher the corrosion rate.

Cutaneous silica granuloma. A rare entity or rarely diagnosed? Report of two cases with review of the literature

Cutaneous silica granuloma is a poorly understood, uncommon condition that may mimic cutaneous sarcoidosis. We describe two cases of this entity and their characteristic latency period (between the time of silica exposure to the time of clinical onset of granuloma). We also review the histologic and energy dispersive x-ray analysis data, which prove the diagnosis. This condition should be recognized as an occupational dermatosis as well as the result of past incidental cuts or abrasions, which result in the development of granulomas, many in old wound scars. Differentiation from cutaneous sarcoidosis is possible with polarized light microscopy and energy-dispersive x-ray analysis.

Clay mineralogy and chemistry as indicators of hemipelagic sediment dispersal south of the Aleutian arc

Near-surface hemipelagic sediments from across the Aleutian arc-trench system were analyzed for clay mineral composition by X-ray diffraction. In addition, oriented aggregates of clay-sized fractions were analyzed for their chemical compositions by energy dispersive X-ray analysis (EDS) in conjunction with scanning electron microscopy. The main clay minerals are illite, chlorite and expandable clay minerals (principally smectite). Smectite is diagnostic of sediment derived from the Aleutian volcanic arc; in contrast, continental sources on the Alaskan mainland produce mainly illite and chlorite. Backarc samples adjacent to the central arc segment contain an average of 71% smectite. In the central forearc, however, smectite values are generally less than 30% and decrease progressively eastward. Only on Meiji Sediment Tongue in the far western Aleutian segment do smectite contents begin to dominate. The EDS data correlate well with clay mineral abundances. Al 2O 3, MgO, and FeO all increase in abundance with increasing chlorite content, and Al 2O 3 and K 2O increase in illite-rich mud. Silica is the only oxide which increases in abundance with increasing smectite content. The compositional and chemical disparity between forearc and backarc sediments is due to dilution of arc-derived mud by suspended sediment derived from mainland Alaska. The westward transport of mud for thousands of kilometers occurs both through isobath-parallel bottom currents and by westward flowing turbidity currents. These results show that interpretations of tectonic provenance cannot be based on elemental concentrations or mineralogy without also taking into account the possibility of long-distance transport.

Coal Combustion Fly Ash Characterization: Electron Spectroscopy for Chemical Analysis, Energy Dispersive X-ray Analysis, and Scanning Electron Microscopy

The surface and bulk properties of five samples of fly ash have been examined by electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). Samples from a conventional pulverized coal combustor, a conventional stoker-fed combustor, and an experimental fluidized bed combustor (FBC) were examined. ESCA data indicated that all samples contained silicon, aluminum, magnesium, calcium, iron, potassium, carbon, oxygen, and sulfur and all but one contained titanium. Samples from the conventional combustors contained more carbon than samples from the FBC. FBC samples contained large amounts of calcium and magnesium. Valence states of some elements were obtained by a detailed examination of selected ESCA peaks. Sputtering was performed on two samples to obtain a depth profile of the composition. The EDXA data confirmed the presence of silicon, aluminum, magnesium, calcium, iron, potassium, sulfur, and titanium while chlorine was detected in some samples. The EDXA data for individual particles exhibited marked particle to particle compositional variation. SEM studies demonstrated that the morphology of FBC samples was different from that of all of the conventional combustor samples examined.