Energy-dispersive X-ray Emission Spectroscopy Research Articles

The electrochemical corrosion behaviour of compacted (Bi, Pb)-2223 superconductors in aqueous solutions

The corrosion behaviour of (Bi, Pb)-2223 samples compacted at 0.3–1.9 GPa in 0.5 M of HCl, NaCl, and NaOH solutions at 30 °C was investigated using potentiodynamic polarization curves measurements and electrochemical impedance spectroscopy (EIS) technique as well as scanning electron microscopy (SEM) and energy dispersive X-ray emission spectroscopy (EDX). Polarization results showed that the increase in compaction decreases both cathodic hydrogen evolution or oxygen reduction and anodic (BiPb)-2223 superconductor dissolution in 0.5 M HCl, and 0.5 M NaOH. On the other hand, compaction mainly affects the anodic part of the polarization curves of (Bi, Pb)-2223 in 0.5 M NaCl solution. EIS measurements revealed that the highest protection of the superconductors was achieved in 0.5 M NaCl, while the lowest degree of protection was observed in 0.5 M HCl. SEM images show a random plate-like morphology fitted with the marker of (Bi, Pb)-2223 material. The compacted sample at 1.9 GPa indicates deformation of the grains and the formation of a micro-crack. The corrosion mechanism of the superconductor at different pH values was also discussed.

Computational Stimulation and Experimental Study on Corrosion Inhibition Qualities of <i>Emilia sonchifolia</i> Leaf Extract for Copper (CU131729) in Hydrochloric Acid

Copper corrosion inhibition by Emilia sonchifolia (ES) leaf extract has been studied in 2 M hydrochloric acid solution using electrochemical measurement, energy dispersive X-ray emission spectroscopy and surface examination techniques. Computational simulations were adopted to describe probable reactiveness of individual ES leaf constituents and mechanism of interaction with copper crystal. Results obtained from potentiodynamic polarization revealed a shift in corrosion potentials of copper (CU131729) to more positive potentials in the presence of ES leaf extract with increased effect as inhibitor concentration increased and also a decrease in both current densities suggesting a mixed type inhibitor characteristics with pronounced anodic protection. Surface elemental characterization revealed presence of the inhibitor species in the corrosion products formed on corroded CU131729 surface confirming the formation of complex chelating ligands through interactions with the metal surface. Quantum chemical calculations and molecular dynamics simulations were employed to theoretically analyse the interactions of individual ES leaf constituent with copper surface at the molecular level and obtained results revealed strong and spontaneous adsorption with high binding energies which affirms observed quality inhibition action. Quantum chemical descriptors such as energy of HOMO and LUMO, energy gap, number of transferred electrons, global hardness and softness, electrophilicity, and interaction energy were computed and discussed.

Synthesis of Pr-doped ZnO nanoparticles: Their structural, optical, and photocatalytic properties**Project supported by the International Cooperation Program of the Ministry of Science and Technology of China (Grant No. 2015DFR00720), the Cooperation Program of Wuhan Science and Technology Bureau, China (Grant No. 2016030409020219), and the Shenzhen Committee on Science and Technology Innovation, China (Grant No. JCYJ20170818112901473).

Undoped and praseodymium-doped zinc oxide (Pr-doped ZnO) (with 2.0-mol%–6.0-mol% Pr) nanoparticles as sunlight-driven photocatalysts are synthesized by means of co-precipitation with nitrates followed by thermal annealing. The structure, morphology, and chemical bonding of the photocatalysts are studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive x-ray emission spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), respectively. The optical properties are studied by photoluminescence (PL) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). We find that Pr doping does not change the crystallinity of ZnO; but it reduces the bandgap slightly, and restrains the recombination of the photogenerated electron–hole pairs. The photocatalytic performance of the photocatalysts is investigated by the photodegradation reaction of 10-mg/L rhodamine B (RhB) solution under simulated sunlight irradiation, showing a degradation rate of 93.75% in ZnO doped with 6.0-mol% Pr.

Corrosion Behavior of a Superconductor with Different SnO2 Nanoparticles in Simulated Seawater Solution

The corrosion behavior of (SnO2)x(Bi1.6 Pb0.4)Sr2Ca2Cu3O10-δ, (SnO2)x(Bi,Pb)-2223, in 0.5 M NaCl solutions at 30°C was studied using potentiodynamic polarization curves measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques as well as scanning electron microscopy (SEM) and energy dispersive X-ray emission spectroscopy (EDX). The polarization data indicated that SnO2 nanoparticles behave as a cathodic type inhibitor for the corrosion of (Bi–Pb)-2223 phase superconductors in simulating seawater solutions. The corrosion current density of (SnO2)x(Bi,Pb)-2223 in a NaCl solution decreases with the time elapsed from sample preparation. The CV of (SnO2)x(Bi–Pb)-2223 phase superconductors showed features similar to those of ideal capacitive behavior. The results indicated that a pure (Bi,Pb)-2223 phase superconductor is the most suitable choice for electrochemical capacitor applications in simulating seawater solutions. However, EIS measurements at different potentials revealed that the corrosion process is controlled not only by charge transfer but also by the diffusion process. These measurements also confirm that the corrosion rate of a cathodically polarized phase superconductor is less than that of an anodically polarized phase superconductor. SEM images and EDX analysis showed that the reduction of SnO2 nanoparticles to Sn decreases the corrosion rates of the superconducting materials.

Determination of Morphology of Poly(3-hexythiophene) with Nanosphere- and Nanorod-Shape of Zinc Oxide

Morphology of thin film poly (3-hexylthiophene) (P3HT) embedded with nanosphere-and nanorod-shape Zinc Oxide (ZnO) has been studied. We deposited the materials on quartz substrate using spin coating technique. The morphology of P3HT: ZnO thin films were investigated using Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray emission spectroscopy (EDX) and RAMAN Spectroscopy and compared. Based on size and shape of both ZnO, it can be seen that nanospheres in P3HT was found to be better than ZnO nanorods in P3HT.

Electrochemistry of soluble UO22+ from the direct dissolution of UO2CO3 in acidic ionic liquid containing water

The direct dissolution of UO2CO3 in neat and “wet” ionic liquid (IL) trimethyl-n-butylammonium bis(trifluoromethansulfonyl)imide [Me3NnBu][TFSI] is examined. The ionic liquid serves as both the solvent for the direct dissolution of UO2CO3(s) and the electrolyte solution for the electrochemical analysis of the soluble uranyl species. The solubility data indicate that displacement of the CO32− occurs slowly due to the low concentration of protons available from residual water in the pristine IL. Enhanced dissolution of UO2CO3 through the formation of carbonic acid H2CO3 is achieved after the addition of acid, bis(trifluoromethanesulfonyl)amide (HTFSI) and water. The soluble uranyl cation can then coordinate with the TFSI anion in place of the displaced CO32− anion following the decomposition of carbonic acid and purging of CO2(g) and water from the IL. The solubility of UO2CO3 was examined using liquid scintillation counting of 233U for the pristine ionic liquid. The “wet” ionic liquid containing HTFSI and soluble UO2CO3 was evaluated using UV/vis spectroscopy before and after dissolution. The electrochemical deposition of uranium species from ionic liquid was evaluated using cyclic voltammetry. The potential mediated deposition of uranium species was achieved and verified using scanning electron microscopy (SEM) and the solid uranium deposits were evaluated using energy dispersive X-ray emission spectroscopy (EDX).

Influence of chemical environment on the analysis of X-ray spectra of thick pellet samples containing 3d transition metal compounds

Nowadays quantitative analysis in energy dispersive X-ray Emission Spectroscopy is usually performed by the “fundamental parameter approach”. Such an approach generally relies upon a good knowledge of fundamental physical parameters. As a rule none of the algorithms in use by laboratories performing routine analysis account for possible chemical effects on X-ray intensity ratios or energies. Here we tested the possible influence of such practice on reliability in the routine analysis of thick pellet samples containing transition metal compounds. A number of samples were prepared by mixing various proportions of MnO2, KMnO4, and Co3O4 (sets A–B) or Cr2O3, K2Cr2O7, and Fe2O3 (C–D). The samples were irradiated by 2 MeV proton beams and proton induced X-ray emission spectra were analyzed by a “fundamental parameter” approach using the GUPIXWIN code. The main interest has been to test the possibility of false Fe detection in the presence of large Mn and Co peaks (sets A–B) and/or Mn in the presence of large Cr and Fe peaks (sets C–D). The results of the analyses indicate false hits of Fe (sets A–B), and larger reported Mn concentrations than expected (sets C–D). However, in all the cases the reported concentrations for Fe or Mn are in between the limits of detection and quantitation. The influence of surface roughness and other effects have been discussed.

Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this "probe-before-destroy" approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. Kβ(1,3) XES spectra of Mn(II) and Mn(2)(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.

Characterization of Electrodeposited Technetium on Gold Foil

The reduction and electrodeposition of on a smooth gold foil electrode with an exposed area of was performed in supporting electrolyte using bulk electrolysis with a constant current density of at a potential of . Significant hydrogen evolution accompanied the formation of Tc deposits. Tc concentrations consisted of and and were electrodeposited over various times. Deposited fractions of Tc were characterized by powder x-ray diffraction, x-ray absorption fine structure spectroscopy, and scanning electron microscopy with the capability to measure semiquantitative elemental compositions by energy-dispersive x-ray emission spectroscopy. Results indicate the presence of Tc metal on all samples as the primary electrodeposited constituent for all deposition times and Tc concentrations. Thin films of Tc have been observed followed by the formation of beads that are removable by scratching. After , the quantity of Tc removed from solution and deposited was . The solution, after electrodeposition, showed characteristic absorbances near corresponding to hydrolyzed Tc(IV) produced during deposition of Tc metal. No detectable Tc(IV) was deposited to the cathode.

X-ray standing waves and scanning electron microscopy — Energy dispersive X-ray emission spectroscopy study of gold nanoparticles

A systematic characterization of mono-disperse nanoparticles with nominal diameters of 25 nm, 46 nm, 73 nm, 100 nm, 115 nm, and 250 nm was performed using X-ray standing waves (XSW). The samples were prepared on Si-wafer pieces and analyzed at DELTA synchrotron facility at beamline BL8 under grazing incidence geometry of the primary radiation. Additionally, SEM-EDX inspections of single particles as well as population-density checks were conducted. Particles with smaller diameters were able be characterized by XSW while the larger ones were not completely covered by the interference field produced by the provided 15 keV monochromatic radiation of BL8. The results of the measurements were compared with those of numerical simulations. The extension of the interference field perpendicular to the Si-wafer reflector was determined to be 83 nm ± 4 nm.

Effect of MgO/CaO ratio on the microstructure of cordierite-based glass-ceramic glazes for floor tiles

The effect of the MgO/CaO ratio on the microstructure and microhardness of cordierite-based glass-ceramic glazes was studied. For this purpose glasses, with compositions in the cordierite primary phase field of the CaO–MgO–Al 2O 3–SiO 2 quaternary system and, with different MgO/CaO ratios, were prepared by melting. Glass powder pellets pressed under low pressure were fast heated at several temperatures simulating industrial floor-tile processing, and characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray emission spectroscopy (EDX). The studied glasses crystallized α-cordierite as the only crystalline phase in the range of temperatures between 1160 and 1190 °C. The glass with intermediate MgO/CaO ratio yielded on heating the relative highest amount of α-cordierite as well as the best well-shaped hexagonal prism crystals. These features were coupled with the highest microhardness value obtained for the glass-ceramic glaze on the tile support.

Cluster analysis for large data sets: applications to individual aerosol particles from the mid-pacific

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.

Structural adaptability in the system Bi 2O 3  WO 3 : Higher members of the homologous series Bi 2W nO 3n+3

The ultramicrostructure of phases with n = 1, 2 and 3 in the hypothetical series Bi 2W nO 3n+3 has been investigated by high resolution electron microscopy and energy dispersive X-ray emission spectroscopy. For n = 1 and 2, well ordered phases with the predicted compositions have been obtained, but for n = 3, a severely disordered assemblage containing intergrowths of the two known structures and strips of the n = 3 member is produced. No evidence for ordered structures with n > 2 has yet been obtained.

Energy-Dispersive X-Ray Emission Spectroscopy

A review is given of recent developments in energy-dispersive x-ray emission spectroscopy, with the aim of providing both an introductory and usefully practical look at this innovative field. The review begins with the first principles of x-ray production and observation, including a brief comparison of the performance capabilities of different types of detectors, but then specializes to a major extent in solid state x-ray spectrometers, which have led to the most significant new developments and applications. Evidence is presented which suggests that we are nearing an asymptotic limit in the attainment of ever better resolution with these types of systems. Applications that have been made possible by significant improvements in system resolution are discussed, but in the context of the need for a realistic appraisal of over-all system requirements. The great advantages offered by the marriage of silicon x-ray spectrometers to scanning electron microscopes and electron microprobe analyzers are reviewed and illustrated.