Wavelength Dispersive X-ray Spectrometer Research Articles

Effect of Chromium Vapor Pressure on Accelerated Poisoning Tests for (La0.6Sr0.4)(Co0.2Fe0.8)O3 Cathode

One of the most critical issues causing degradation of SOFCs is poisoning of cathodes by a trace amount of impurities transferred with air such as sulfur (S) and chromium (Cr), and therefore, we are continuously investigating the test method on accelerated degradation by these impurities. In our previous studies on Cr poisoning, chromium metal covered with Cr2O3 was directly placed on the current collector of the cathode as a source of Cr vapor. However, the setting accelerated the performance degradation in surplus. In order to perform accerelated poisoning test at an appropriate rate, we improved the cell operating equipment to control the Cr vapor pressure during the cell tests. The Cr vapor pressure was controlled by adjusting the place and temperature of the Cr source. The cell tests were operated at 1073 K under controlled feeding rate of Cr vapor after the cell performance became stable. The degradation behavior was analyzed with AC impedance analysis, field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDX) / wavelength-dispersive X-ray spectrometer (WDS). The vapor pressure of Cr species was estimated from the amount of Cr trapped by (Sm,Sr)CoO3cathode in the same equipment of cell tests. The degradation rate decreased with decreasing the Cr vapor pressure, and the amount of Cr species deposited in LSCF cathode decreased with decreasing the Cr vapor pressure.

High-resolution X-ray emission spectroscopy with transition-edge sensors: present performance and future potential.

X-ray emission spectroscopy (XES) is a powerful element-selective tool to analyze the oxidation states of atoms in complex compounds, determine their electronic configuration, and identify unknown compounds in challenging environments. Until now the low efficiency of wavelength-dispersive X-ray spectrometer technology has limited the use of XES, especially in combination with weaker laboratory X-ray sources. More efficient energy-dispersive detectors have either insufficient energy resolution because of the statistical limits described by Fano or too low counting rates to be of practical use. This paper updates an approach to high-resolution X-ray emission spectroscopy that uses a microcalorimeter detector array of superconducting transition-edge sensors (TESs). TES arrays are discussed and compared with conventional methods, and shown under which circumstances they are superior. It is also shown that a TES array can be integrated into a table-top time-resolved X-ray source and a soft X-ray synchrotron beamline to perform emission spectroscopy with good chemical sensitivity over a very wide range of energies.

EBIS-A facility for the studies of X-ray emission from solids bombarded by highly charged ions

We report here on the progress in the X-ray spectroscopy program at the EBIS-A facility installed recently at the Institute of Physics of Jan Kochanowski University in Kielce. In this facility the beams of low-energy highly charged ions (HCI) produced by the Dresden EBIS-A ion source, after extraction and charge-state separation in the double focusing magnet, are directed to the experimental UHV chamber equipped with a 5-axis universal sample manipulator. The X-rays emitted in interaction of the highly charged ions with solids can be measured by an energy dispersive X-ray silicon drift detector (SDD) and/or a wavelength-dispersive X-ray spectrometer (WDS) mounted at the experimental chamber. The surface nanostructures formed by an impact of HCI will be studied by the grazing emission X-ray fluorescence (GEXRF) technique and using a multiprobe surface analysis system based on the X-ray photoelectron spectrometer (XPS) coupled to the UHV chamber of the EBIS-A facility. In this paper a brief description of the facility, X-ray instrumentation and the surface analysis system is given and the first results are presented.

Cavitation erosion resistance and wear mechanisms of active screen low temperature plasma nitrided AISI 410 martensitic stainless steel

Quenched and tempered AISI 410 martensitic stainless steel specimens were active screen plasma nitrided in a mixture of 75% of nitrogen and 25% of hydrogen during 20h at 400°C. The microstructure of the nitrided case was characterized by optical microscopy, scanning electron microscopy and microhardness measurements. The phases were identified by X-ray diffraction and the nitrogen content as a function of depth was measured using wavelength dispersive X-ray spectrometer coupled to SEM. Nanoindentation tests were carried out in order to assess hardness (H), Young modulus (E), H/E and H3/E2 ratios and the elastic recovery (We) of the nitrided layer. Cavitation erosion tests were carried out according to ASTM G32 standard during 20h, with periodical interruptions for registering the mass losses. Additional cavitation erosion tests were performed to identify the wear mechanisms in both specimens, through assessment of the evolution of the damage on the surface, in a scanning electron microscope. A ~28µm thick, 1275 HV hard nitrided case formed at the surface of the martensitic stainless steel, composed of nitrogen supersaturated expanded martensite and hexagonal ε-Fe24N10 iron nitrides. The expanded martensite decreased 27 times the mass loss shown by the non-nitrided stainless steel and the erosion rate decreased from 2.56mg/h to 0.085mg/h. The increase in cavitation erosion resistance can be mainly attributed to the increase in hardness and to the elastic response of the expanded martensite. The non-nitrided specimen changed from initially ductile to brittle behavior, exhibiting two different modes of material detachment. The first mode was characterized by a great degree of plastic deformation, fatigue and ductile fracture. The second failure mode could be associated to brittle fracture by cleavage mechanisms. In contrast, the wear mechanism observed in the nitrided specimen was brittle fracture without evident plastic deformation.

Efficacy of Foliar Application of Calcium Products on Tomatoes as Defined by Penetration Depth of and Concentration within Fruit Tissues

The efficacy of ion absorption through the cuticle of a leaf of fruit has been related the conditions whilst applying (i.e., environmental) and the receiving surface exposure (i.e., area covered, capacity of absorption). The influence of the product's physical chemical properties like point of deliquescence should be taken under consideration while quantifying penetration. The present study compares traditional and recent calcium formulations (total of 10) by evaluating calcium penetration and distribution on tomato fruits as well as comparing plant health and fruit quality. Elemental analysis through Wavelength Dispersive X-ray Spectrometer (WDS) analysis, using a Zeiss EVOR_MA15 SEM (Carl Zeiss Pty. Ltd., Cape Town, South Africa) and mineral analysis were used to quantify calcium content in the fruit. In addition, maturity index parameters were taken before and after storage (10 days at 15°C). Nitrogen, phosphorus, magnesium and calcium did not differ significantly after treatment according to elemental and mineral analysis. Calcium concentration in the fruit was successfully increased.

Thermal stability and flame retardancy of guanidinium and imidazolium borate finished cotton fabrics

The aim of this study was to investigate the effect of guanidinium nonaborate (GB) and imidazolium borate (IB) on thermal stability and flammability properties of cotton fabrics. The flame retardant and thermal stability properties of treated cotton fabrics were investigated using limiting oxygen index (LOI) and thermogravimetric analysis. The residues remained after LOI test were characterized by conducting attenuated total reflectance-Fourier-transform infrared spectroscopy and scanning electron microscopy with a wavelength-dispersive X-ray spectrometer. The results showed that both boron compounds increased the LOI value of cotton fabric as the amount increased by several combined flame retardant effects. IB-treated cotton fabrics had higher LOI value than GB-treated ones due to the higher increment in char yield which was the predominant flame retardant action of both boron compounds.

Improving the energy resolution of bent crystal X-ray spectrometers with position-sensitive detectors.

Wavelength-dispersive high-resolution X-ray spectrometers often employ elastically bent crystals for the wavelength analysis. In a preceding paper [Honkanen et al. (2014). J. Synchrotron Rad. 21, 104-110] a theory for quantifying the internal stress of a macroscopically large spherically curved analyser crystal was presented. Here the theory is applied to compensate for the corresponding decrease of the energy resolution. The technique is demonstrated with a Johann-type spectrometer using a spherically bent Si(660) analyser in near-backscattering geometry, where an improvement in the energy resolution from 1.0 eV down to 0.5 eV at 9.7 keV incident photon energy was observed.

Focus on photonics and biomedical optics

Focus on photonics and biomedical optics

High energy resolution PIXE spectroscopy at the J. Stefan Institute, Ljubljana

While traditional proton induced X-ray emission (PIXE) analytical technique is based on the energy dispersive solid state detectors used to collect the X-ray fluorescence from the sample, wavelength dispersive X-ray (WDX) spectrometers are applied in high energy resolution PIXE (HR-PIXE) analysis. The main drawback of the WDX spectroscopy is the relatively low efficiency making it less applicable for trace element PIXE analysis. However, the efficiency was enhanced significantly in modern spectrometers employing cylindrically or even spherically curved crystals combined with position sensitive X-ray detectors. The energy resolution of such a spectrometer may exceed the resolution of the energy dispersive detector by two orders of magnitude while keeping the efficiency at a high enough level to perform trace element analysis. In this paper, the recent history and the development of HR-PIXE spectroscopy at the J. Stefan Institute in Ljubljana is presented. Our current setup based on in-vacuum Johansson-type crystal spectrometer is presented in more details followed by some most recent applications.

Development of a WDX-μ-PIXE system for chemical state mapping

In this paper, we have developed a wavelength dispersive X-ray spectrometer microparticle-induced X-ray emission (WDX-[Formula: see text]-PIXE) system combining a microbeam system with high spatial resolution and wavelength dispersive X-ray (WDX) spectrometry with high-energy resolution for chemical state mapping. A Von Hamos geometry was used for the WDX system to achieve higher detection efficiency and energy resolution. The system consists of a curved crystal and a CCD camera. The WDX system was installed in a newly developed microbeam system. The energy resolution of the WDX system was 0.67 eV for [Formula: see text] (1740 eV). [Formula: see text] and [Formula: see text] X-ray spectra from various Si compounds were measured and chemical shifts related to chemical states were clearly observed. The system was applied to the chemical state analysis of clay particles. After elemental mapping of the clay particles using a conventional [Formula: see text]-PIXE system with a Si(Li) detector, particles to be analyzed were selected and analyzed sequentially with the WDX system. [Formula: see text] spectra from clay particles were obtained. The microscopic spatial distribution of elements and chemical state of the clay particles were sequentially measured with high energy and spatial resolution using a microbeam.

High cycle fatigue and fracture behaviour of a hot isostatically pressed nickel-based superalloy

Powder of a nickel-based superalloy, RR1000, has been hot isostatically pressed (HIPped) at a supersolvus temperature and post-HIP heat treated to produce different microstructures. Microstructures were investigated using a scanning electron microscope together with an energy dispersive X-ray spectrometer and a wave-length dispersive X-ray spectrometer. High cycle four-point bending fatigue and tension–tension fatigue tests have been performed on the fabricated samples. It was found that HIPped and aged samples showed the best four-point bending fatigue limit while HIPped and solution-treated and aged samples had the lowest fatigue limit. The four-point bending fatigue crack initiations all occurred from the sample surfaces either at the sites of inclusion clusters or by cleavage through large grains on the surfaces. The tension–tension fatigue crack initiation occurred mainly due to large hafnia inclusion clusters, with lower fatigue lives for samples where inclusions were closer to the surface. Crack initiation at the compact Al2O3 inclusion cluster led to a much higher fatigue life than found when cracks were initiated by large hafnia inclusion clusters. The tension–tension fatigue limits were shown to decrease with increased testing temperature (from room temperature to 700 °C).

Influence of Heat Treatment on the Microstructure and Magnetic Properties of Mn–Sn–Co–N Alloys

This paper describes the influence of heat treatment on the microstructure and magnetic properties of Mn­Sn­Co­N alloys. After homogenization at 950°C for 20 h in Ar, Mn82.5Sn10Co7.5 alloys were annealed at 900°C for 1­20 h in N2 and quenched to room temperature (first-annealing). The alloys were subsequently annealed at 400­700°C for 5 h in N2 and quenched to room temperature (second-annealing). The coercivity of the alloys changed drastically by the second annealing. The samples subjected to second annealing at 500°C showed maximum coercivity of 1270 kAm11 and exhibited a fine two-phase microstructure. Wavelength Dispersive X-ray Spectrometer (WDS) and X-ray Diffraction (XRD) analyses revealed that the fine two-phase microstructure consists of ¢-Mn and perovskite-type (Mn4N-like) phases, as well as that the two phases emerged from the ¦A phase during the second-annealing at 500°C. [doi:10.2320/matertrans.MAW201312]

A multi-crystal wavelength dispersive x-ray spectrometer

A multi-crystal wavelength dispersive hard x-ray spectrometer with high-energy resolution and large solid angle collection is described. The instrument is specifically designed for time-resolved applications of x-ray emission spectroscopy (XES) and x-ray Raman scattering (XRS) at X-ray Free Electron Lasers (XFEL) and synchrotron radiation facilities. It also simplifies resonant inelastic x-ray scattering (RIXS) studies of the whole 2d RIXS plane. The spectrometer is based on the Von Hamos geometry. This dispersive setup enables an XES or XRS spectrum to be measured in a single-shot mode, overcoming the scanning needs of the Rowland circle spectrometers. In conjunction with the XFEL temporal profile and high-flux, it is a powerful tool for studying the dynamics of time-dependent systems. Photo-induced processes and fast catalytic reaction kinetics, ranging from femtoseconds to milliseconds, will be resolvable in a wide array of systems circumventing radiation damage.

Control of the chemical state change of sulfur in solid compound targets during high-resolution PIXE measurements

A high-energy-resolution wavelength-dispersive (WD) X-ray spectrometer in the Johansson geometry, which allowed energy resolution below the natural linewidth of the Kα lines was employed in measurements of the proton-induced Kα X-ray emission spectra for six typical sulfur compounds (CdS, Na2SO3, Na2 S2O5, NaHSO3, (NH4)2SO4, and Na2SO4) to investigate the chemical state change during 2.4-MeV proton irradiation with a current density of 7.5 nA/mm2. We found that the chemical state change of each compound depended on the various factors affecting the surface temperature increase, such as target thickness, mounting method, and existence of active cooling during the measurement. The chemical state of sulfur on the target surface of S4+ compounds was gradually changed into S6+ without exception through irradiation under poor cooling conditions. Sulfur compounds of the S0 and S6+ states with closed shell structures were proven to be chemically stable against proton bombardment, as expected. However, (NH4)2SO4 was found to be most sensitive to proton irradiation among the sulfur compounds, and S0, one of the reaction products, became a major element at doses higher than 3 × 108 Gy. If thick targets were mounted by using a carbon adhesive tape, chemical state change could be observed in some cases even with lowtemperature cooling down to −80 °C, however, the chemical state change seemed to be remarkably suppressed by using very thin targets mounted with a silver paste even without active cooling. In conclusion, the chemical states of sulfur compounds could be preserved without significant change for an accumulated dose of about 3 × 107 Gy, equivalent to a typical high-resolution PIXE scanning period, by adopting a proper target preparation scheme to discharge proton-induced thermal energy effectively from the irradiated target surface.

Shielded field emission EPMA for microanalysis of radioactive materials

A standard Jeol 8500F electron probe microanalyzer (EPMA) with field emission gun (FEG) has been installed in a lead shielded cabin of the laboratory and customized for remote control. The wavelength-dispersive X-ray spectrometers (WDS) have been additionally shielded against β,γ-radiation with tungsten alloy modules. These measures have proven to be very effective for the examination of specimens with an activity of less than 20 GBq 137Cs. The background intensity is dependent on crystal type, spectrometer and sample position. The efficiency of the spectrometer with Xe-sealed counter is higher but also its sensitivity to the specimen's γ-radiation than the Ar/CH4 flow counter. The possibility of applying high beam currents increases the peak-to-background ratio for the analysis of low concentrations in the active sample. The high electron beam density of the FE-gun allows for the recording of high resolution elemental X-ray maps in the range of a few tenths of a micrometre at even medium acceleration voltage and thus short acquisition time. It is thus a valuable instrument in post irradiation examinations of spent fuel rods and materials irradiated by other sources.

Application of field emission scanning electron microscopy for observing irradiated fuel materials

ABSTRACTThe microstructure change of the uranium-plutonium mixed oxide fuels (MOX fuels) irradiated in a fast reactor occurs because of a radial temperature gradient. To make detailed observations and elemental analyses of fuel samples, a field emission scanning electron microscope (FE-SEM) equipped with a wavelength-dispersive X-ray spectrometer (WDX) was installed in a hot laboratory.Because fuel samples have high radioactivities and emit α-particles, the instrument was modified as follows :1)The instrument was attached to a remote control air-tight sample transfer unit between a shielded hot cell and the FE-SEM.2)The FE-SEM was installed in a lead shield box and the control unit was separately located outside the box.After the installation, the microscopy and elemental analyses were applied to low burnup fuel samples. High resolution images were obtained and characteristic X-rays (U, Pu, and so on) emitted from the sample surface were measured. The technique has the great advantage of being able to evaluate the irradiated fuels in detail. In future work, samples of even higher radioactive will be observed and analyzed.

Removal of benzene by ZnO nanoparticles coated on porous adsorbents in presence of ozone and UV

Benzene is an air toxic that is released from various emission sources including traffic and various industries. The aim of this study was to investigate the benzene removal performance of ZnO nanoparticles (nZnO) coated on 13X zeolite and activated carbon (AC) at a ratio of Zn to zeolite and Zn to AC of 0.5:1.0 by weight. The coated adsorbents were characterized by scanning electron microscope (SEM) and wavelength dispersive X-ray Spectrometer (WDX). The laboratory scale experiments were conducted at ambient temperatures (∼30°C) with UV, O3 and UV+O3 respectively introduced. The inlet benzene was 5ppm in all the experiments. The coated zeolite had the benzene removal efficiency (RE) of 97.9±0.9% compared to 94.2±2.4% of the virgin zeolite. The UV, O3 and UV+O3 treatments slightly increased the RE of the zeolite experiments, i.e. 98.4±0.4%, 98.2±1.0% and 98.9±0.2%, respectively. Meanwhile, the RE by the virgin AC was slightly higher than the coated AC, i.e. 99.5±0.2% compared to 98.3±0.1%. With UV, O3 and UV+O3 introduced the coated AC adsorbent similarly demonstrated a good RE, i.e. 99.0±0.1%, 99.0±0.2% and 98.2±0.3%, respectively. A combination of UV, O3 and UV+O3 could produce combined effects of adsorption, photodegradation and oxidation for benzene removal. The breakthrough test results revealed that the coating significantly reduced the service time (the period before the breakthrough occurs) for both adsorbents (zeolite and AC) in all experimental conditions. Various intermediate products: formaldehyde, acetaldehyde, ethanol, methanol and carbon monoxide (CO) found in the outlet stream confirmed a potential competing adsorption of these intermediate products and also the final products (CO2, water vapor) that reduced the adsorbent capacity in addition to a partial blockage of AC pores by nZnO.

Compact crystal spectrometers for ion microbeam WDX–PIXE applications

AbstractThe use of a CCD for detection of X‐rays and a focused or collimated beam of ionising radiation enables the design of a compact, wavelength‐dispersive X‐ray (WDX) spectrometer, with increased solid angle and tolerable loss of energy resolution. Experimental investigation of WDX spectrometer designs is rather expensive and time consuming, so in order to compare various designs, a numerical X‐ray tracing procedure (XTRACE) has been developed for the calculation of instrumental functions and solid angles. XTRACE has been applied to a range of candidate designs for downsized WDX spectrometers with CCD detection and flat, Von Hamos, Johann, Johansson and spherical crystals. Most of the crystal types studied for use in downsized WDX‐PIXE spectrometers are sensitive to sample surface rotation, which may affect the reproducibility of experimental conditions. Implications for construction of downsized WDX spectrometers for PIXE application using an ion microbeam are given. Copyright © 2011 John Wiley & Sons, Ltd.

Coupling a wavelength dispersive spectrometer with a synchrotron-based X-ray microscope: A winning combination for micro-X-ray fluorescence and micro-XANES analyses of complex artistic materials

X-Ray fluorescence (XRF) is one of the most established techniques for the analysis of works of art. It offers several features—such as non-invasiveness, richness of information, in situ analysis with portable instruments and 2D and 3D micro-imaging when performed at synchrotron sources—which are increasingly used in the field of Cultural Heritage science. However, the complexity of artistic materials may lead into complex XRF spectra. Overlapping of fluorescence emission lines can make XRF analyses prone to error. In this article, we discuss the attributes of the polycapillary-based Wavelength Dispersive X-ray Spectrometer (WDS) developed at the X-ray micro-spectroscopy ESRF beamline, ID21. With spectral resolution of a few tens of eV, this system allows better separation of neighbouring emission lines. Its pros and cons for micro-XRF point analysis, micro-XRF mapping and micro-XANES are addressed, with a particular focus on Cultural Heritage applications. Possible extensions towards micro-RIXS are also discussed.

Chemical characterization of a high nitrogen stainless steel by optimized electron probe microanalysis

The distribution of Cr and N in a high-temperature gas-nitrided stainless steel was measured by using a scanning electron microscope-coupled wavelength-dispersive X-ray spectrometer and the results were related to the microhardness profile of the hardened case. The experimental spectrometric procedure was optimized to consistently measure N contents varying between 0.1 and 0.8 wt.% in martensite and between 18.3 and 21.6 wt.% in nitrides, as well as Cr contents ranging from 11.5 to 17.0 wt.%.