Glow Discharge Mass Spectrometry Research Articles

Calibration of double focusing Glow Discharge Mass Spectrometry instruments with pin-shaped synthetic standards

Calibration of two commercially available glow discharge double focusing mass spectrometers, the VG 9000 and Element GD, is described using synthetic pin standards pressed from solution doped copper and zinc matrices. A special pressing die was developed for this purpose and optimal results were obtained with the highest possible pressures, i.e., 95 kN·cm − 2 . This calibration approach permits the determination of trace element mass fractions down to μg·kg − 1 with small uncertainties and additionally provides traceability of the GD-MS results in the most direct manner to the SI (International System of Units). Results were validated by concurrent measurements of a number of compact copper and zinc certified reference materials. The impact of the sample pin cross-section (circular or square) was investigated with the use of a new pin-sample holder system for the Element GD. The pin-sample holder was designed by the manufacturer for pin-samples having circular cross-section; however, samples with square pin cross-section were also shown to provide acceptable results. Relative Sensitivity Factors for some 50 analytes in copper (VG 9000, Element GD) and zinc matrices (VG 9000) are presented. The field of applicability of GD-MS may be considerably extended via analysis of pin geometry samples based on their ease of preparation, especially with respect to the accuracy and traceability of the results and the enhanced number of analytes which can be reliably calibrated using such samples.

Glow discharge mass spectrometry studies on nephrite minerals formed by different metallogenic mechanisms and geological environments

Glow discharge mass spectrometry (GD-MS) was applied to study the nephrite minerals formed by different metallogenic mechanisms and geological environments from deposits in China, Canada, New Zealand and Russia. The GD-MS analysis and multivariate statistic analysis results indicated that two types of nephrite minerals of different metallogenic mechanisms could be classified by some typical elements. It was shown that serpentine-related nephrite minerals had higher concentrations of Cr, Co and Ni than dolomitic-marble-related nephrite minerals. Meanwhile, nephrite samples from Wenchuan had higher concentrations of Mn, V than other deposits and nephrite samples from Xiaomeiling had higher concentrations of Sr, K and Na than other deposits, which were consistent with their geological environments. These analytical results of nephrite samples by GD-MS showed that both metallogenic mechanisms and geological environments could affect the elemental concentrations in nephrite minerals.

Effects of gradient heat treatment on Te-rich CdZnTe crystal

The gradient heat treatment was performed on Te-rich CZT crystal grown by the vertical Bridgman (VB) method, which was under the temperature of 1073 K and the temperature gradient of 2 K/mm and the velocity of 1.8 mm/h. IR transmission, IR microscope, I–V curves and glow discharge mass spectrometry (GDMS) revealed that Te inclusions moved towards the last-to-freeze region in CZT ingot, which proved that the gradient heat treatment has the possibility to purify the CZT ingot. Finally, after the gradient heat treatment, the resistivity of the CZT ingot was enhanced, and the IR transmittance was also improved.

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

As a continuation to earlier work on the silver-point realization, already reported at TEMPMEKO 2007, a new silver-point cell has been fabricated using 6N-nominal grade material that was analyzed by means of glow discharge mass spectrometry (GDMS) by the manufacturer. This new cell is evaluated by a direct cell comparison with one of the existing cells, which was also already reported at TEMPMEKO 2007. One of those existing cells was drawn out from its crucible, and its ingot was analyzed by GDMS at four positions, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of middle areas for the purpose of confirming whether or not there has been differences in the content of impurities before and after the cell fabrication, as well as differences in impurity homogeneity within the ingot. As results of the aforementioned measurements, it was found that the homogeneity of impurities in the silver ingot was on average within 50 %. It was also found that cell-to-cell temperature differences change along with the progressing solidification process. As a consequence, it was concluded that, for an accurate cell-to-cell comparison, the location in the freezing plateau, where the comparison is done, should be determined. Also obtained here is that the slope analysis was consistent with both the cell-to-cell comparison and the impurity analysis.

On the Impurity Parameters for Impurities Detected in the Eutectics Co–C and Pt–C and Their Role in the Estimate of the Uncertainty in the Eutectic Temperatures

In this paper, impurity parameters mi and ki have been calculated for a range of impurities I as detected in the eutectics Co–C and Pt–C, by means of the software package Thermo-Calc within the ternary phase spaces Co–C-I and Pt–C-I. The choice of the impurities is based upon a selection out of the results of impurity analyses performed for a representative set of samples for each of the eutectics in study. The analyses in question are glow discharge mass spectrometry (GDMS) or inductively coupled plasma mass spectrometry (ICP-mass). Tables and plots of the impurity parameters against the atomic number Zi of the impurities will be presented, as well as plots demonstrating the validity of van’t Hoff’s law, the cornerstone to this study, for both eutectics. For the eutectics in question, the uncertainty u(TE − Tliq ) in the correction TE − Tliq will be derived, where TE and Tliq refer to the transition temperature of the pure system and to the liquidus temperature in the limit of zero growth rate of the solid phase during solidification of the actual system, respectively. Uncertainty estimates based upon the current scheme SIE–OME, combining the sum of individual estimates (SIE) and the overall maximum estimate (OME) are compared with two alternative schemes proposed in this paper, designated as IE–IRE, combining individual estimates (IE) and individual random estimates (IRE), and the hybrid scheme SIE–IE–IRE, combining SIE, IE, and IRE.

Synthesis of Hf-modified aluminide coatings on Co-base superalloys

Hf-modified and Hf–Pt-modified aluminide coatings on Haynes 188 Co-base alloy coupons were developed and furthermore, Hf-modified aluminide coatings on MAR-M-509 Co-base aircraft turbine engine vane segments were produced for potential industrial applications. Surface morphology and cross-section microstructure of the developed coatings were inspected and compared by using Scanning Electron Microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and Glow-Discharge Mass Spectrometry (GDMS). Experimental results showed that Hf was successfully incorporated and localized Hf-rich precipitated phase particles were observed on the coating surface and within the coating additive layer. The Hf-rich particles and the effect of heat treatment on the particles are also discussed.

Comprehensive Comparison of Various Techniques for the Analysis of Elemental Distributions in Thin Films

The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.

Synthesis of Hf-modified aluminide coatings on Ni-base superalloys

With small additions of Reactive Elements (RE), such as hafnium (Hf), to aluminide coatings applied on aircraft turbine engine components, the adherence of the protective oxide scale to the coatings and the oxidation resistance of the coatings at high temperatures can be significantly improved. At SIFCO, Hf-modified aluminide coatings, Hf–Pt-modified aluminide coatings on Ni-base superalloys and the industrial-scale production of Hf-modified aluminide coatings on different aircraft turbine engine components were successfully developed. Surface morphology and cross-section microstructure of the developed coatings were inspected and compared by using a Scanning Electron Microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and Glow-Discharge Mass Spectrometry (GDMS). Experimental results showed that Hf was successfully incorporated and precipitated Hf-rich particles were observed on the coating surface, along grain boundaries within the additive layer, and at the interface between the additive layer and the interdiffusion layer. Finally, Hf-rich particles as well as Hf solubility are discussed.

Atmospheric identification of active ingredients in over‐the‐counter pharmaceuticals and drugs of abuse by atmospheric pressure glow discharge mass spectrometry (APGD‐MS)

Atmospheric pressure glow discharge mass spectrometry was used to characterize the active ingredients in pharmaceutical over-the-counter (OTC) drug formulations (Tylenol Allergy, Alka-Seltzer Plus Nighttime, Sudafed, Aleve and Mucinex DM) and drugs of abuse (crack cocaine, methamphetamine, MDMA (ecstasy) and hydrocodone). Material was desorbed and directly ionized under atmospheric conditions by allowing the substance to come in direct contact with the plasma followed by mass spectrometric detection. With this technique, controlled substances and OTC medications were readily distinguished from one another. Characteristic mass spectra were identified for the active ingredients in the OTC and drugs of abuse. Importantly, all drug compounds studied here, both OTC and illicit, demonstrated signals for either molecular ions or protonated molecules as well as fragmentation patterns that are readily identified in the National Institute of Standards and Technology (NIST) electron ionization (EI) mass spectral library. It is believed that this technique holds promise for forensic and law enforcement communities for real-time atmospheric analysis of drugs with database-searchable spectra of controlled substances.

The Influence of Titanium on the Aluminum Fixed-Point Temperature

This work describes the deliberate doping of high purity (99.9999 %) aluminum with titanium (99.8 %) impurity and the effect of this on the temperature of the aluminum liquid–solid phase transition (660.323 °C). The aluminum sample was in the form of an ~0.3 kg ingot (that would normally be used to realize an ITS-90 fixed point) which was doped at ~0.9 ppmw Ti and ~1.8 ppmw Ti (mass fraction in parts per million by mass). Measurements were made with procedures and equipment normally used in a metrological thermometry laboratory, rather than using special arrangements. Samples cut from the aluminum ingot were chemically analyzed by glow discharge mass spectrometry (GD-MS) before doping and after the second doping (to 1.8 ppmw). The experimental temperature offsets were compared with those calculated by interpolation from a reference book value using the mass of dopant introduced, or the chemical analysis data. The results showed that the aluminum temperature increased after adding 0.9 ppmw Ti, but apparently the temperature did not change after further doping to 1.8 ppmw Ti; which was unexpected. The first result suggested that titanium impurity increases the Al transition temperature by +5.1 mK · ppmw−1. However, using the (total) temperature offset and the GD-MS value for the (total) added Ti impurities, then one calculates a value of 3.4 mK · ppmw−1 (much closer to a reference book value). The experimental undoped liquid–solid transition curves were also compared against theoretical curves (calculated using a theoretical model “MTDATA”). This suggested that GD-MS may not be “exposing” all the active impurities (some of which may be “hidden” in the carbon background).

Study of Dislocation Generation and Growth Orientations in Upgraded Metallurgical Grade Multicrystalline Silicon

We used high-purity multicrystalline silicon prepared by metallurgical method for the study of directional solidification. The optical microscope was used to observe the etch pits on the surface of silicon wafers, and we calculated their dislocation density. The result showed the space distribution of dislocation density presented “V” shape for each ingot produced at different drop-down rates. The dislocation density of slicon ingots followed the order 10<20<30<40μm/s. The high-resolution glow discharge mass spectroscopy was used to analyze the concentration of transition metal impurities. The macro-morphology of vertical-section of silicon ingots growth at different drop-down rates was observed. The x-ray diffraction measurement was performed to analyze the crystallographic orientations of the silicon ingot growth at 20μm/s, which was a better drop-down rate for producing high-quality multicrystalline silicon.

Studies on the Element Characteristics of Nephrite Minerals from Different Deposits by GD-MS

Element characteristics of nephrite minerals were determined by glow discharge mass spectrometry (GD-MS) through surface adherence method. To solve the conductivity problem of non-conductive nephrite samples, high purity indium pin (>99.9999%) was used as discharge host. During the preparation procedure, a small piece of nephrite sample was ground into powder (about 200 meshes), and then the sample powder was coated on the surface of indium pin to form a rod sample. Typical elements of nephrite minerals were analyzed by GD-MS, and the relative standard deviations showed that the stability and reproducibility of this method were good. Meanwhile, four nephrite samples from two different deposits were further studied by this method. The GD-MS results of major elements and trace elements revealed that typical elements of the nephrite minerals from same deposit were similar, and those from different deposits exhibited significant difference. In addition, results of external-beam proton induced X-ray emission (PIXE) were consistent with the result of GD-MS determination. The present approach had been proven to be simple, efficient to perform the rapid screening and multi-element semi-quantitative analysis of nephrite samples.

The Effect of Low Level Antimony on the Tin Temperature Fixed Point

Impurities are a major source of uncertainty in the temperature of a thermometry metal fixed point (of the order of 1 mK). A better understanding of the impurity effect is required to improve top-level metrological thermometry. This investigation reports on some unusual effects of antimony doped into a high-purity (99.9999%) tin sample. The change in temperature and shape of the melting and freezing curves of the tin, caused by low concentrations of the Sb dopant, were measured in order to test the interpolation of previous data. Most historical experiments have worked at much higher impurity concentrations—say of the order of 100 ppm—and in arrangements that are not used on a day-to-day basis in a metrology laboratory. These measurements on the tin were done after doping at mass fractions of approximately (1 and 25) parts per million by weight (ppmw) of antimony. Repeated melting and freezing curves, before and after doping, confirmed the reproducibility of the temperature measurements in this tin cell. The freezing temperature of the tin after adding antimony was higher than for “pure” tin. However, the temperature change was less than expected, being an average (+0.06±0.03) mK · ppmw−1. Samples from the tin were analyzed by glow discharge mass spectrometry (GD-MS) before and after doping to detect the distribution of all the impurity elements. If the dopant level detected by GD-MS was used, then a value of (0.18 or 0.29) mK · ppmw−1 was calculated (much closer to the value interpolated from earlier works). There was evidence that the thermal history of metal phase transitions can cause considerable segregation of some impurities and that the effects of this segregation can be clearly seen on the shape of the melting curves of tin doped with Sb. (The segregation might be more pronounced as Sb forms a peritectic in tin, i.e., a “positive” impurity which increase the phase transition temperature).

Determination of relative sensitivity factors for trace element analysis of solar cell silicon by fast-flow glow discharge mass spectrometry

A commercially available Element GD, the latest generation of glow discharge mass spectrometry (GDMS), has been used for quantitative analysis of impurities in silicon for photovoltaic applications (PV silicon). In order to be able to accurately measure impurities in silicon, relative sensitivity factors (RSFs) need to be determined. These factors are, currently, given only for steel matrices. In this study, standard silicon materials with known levels of impurities have been produced and independent analytical methods have been used for determining the RSFs for silicon matrices. It has been found that the tuning parameters of the Element GD, mainly the discharge gas flow rate, influence the RSF values. In addition, it has been found that RSF values are matrix specific; RSFs for a silicon matrix differ significantly from those for metallic conductor matrices even under identical instrumental parameters. A study of the relative reproducibility in the quantitative analysis of impurities in solar cells silicon has shown variations between 5% and 12%.

Effects of vacuum heating in AISI 410 and AISI 321 stainless steels' surface layer revealed by SIMS/GDMS depth profile analysis

AbstractVacuum annealing of steels is employed for out‐gassing elements, surface activation and in different production purposes. Such procedure was applied for chromium–nickel AISI 321 and chromium AISI 410 stainless steels used in aviation technologies.Depth profile analysis of the samples annealed in vacuum for 120 min. in 750 and 950 °C was performed by using two methods: SIMS and glow discharge mass spectrometry (GDMS). SIMS data were obtained with a 5 keV Ar+ ion gun. In GDMS analyzer, d.c. glow discharge was induced by 1.5 kV d.c. voltage in 1 mbar Ar pressure.Analyses of AISI 321 samples annealed in 750 °C show enrichment of titanium, chromium and manganese in the depth range of 150 nm, and depletion in iron and nickel within this range. The sample treated in 950 °C shows mainly Ti enrichment into 300 nm depth. Vacuum heating of AISI 410 steel sample in 750 °C causes formation of 150‐nm‐thick surface layer enriched in Cr and Mn and depleted in Fe. In turn, 950 °C treatment results in only some increasing of Mn and Ni concentration within 70 nm distance from the surface.The results obtained by SIMS and GDMS confirm each other. However, higher depth profile resolution was obtained by GDMS due to the lower sputtering energy (1.5 kV glow discharge) and due to the use of multidirectional ion bombardment instead of unidirectional bombardment by ion beam in the SIMS method. Copyright © 2010 John Wiley & Sons, Ltd.

超高真空溶解による6Nアルミニウム素材の高純度化

In order to improve the purity of 6N aluminum, it was melted in a vacuum of 3-6×10−6 Pa for 30 min and solidified gradually. The melted samples were cut into several pieces and the residual impurities of each part were analyzed by Glow Discharge Mass Spectrometry (GDMS). The Residual Resistivity Ratio (RRR) of each part was measured and the relationship of RRR with residual impurities is discussed. The purity of the melted sample was improved in comparison with that of the raw material, and the measured RRR almost doubled to 40000. GDMS analysis revealed that the amounts of elements of partition coefficient k 1 were not reduced. While each impurity concentration ratio in this study is about one-tenth of that in the previous report, the purification efficiency of each element in this study and that in the previous report matched well. Although the estimated RRR values from composition analyses were larger than the measured RRR values, both showed similar tendencies with regard to specimen position and also corresponded well with regard to impurity distribution.

Direct FexOy speciation in solid state materials by pulsed millisecond radio frequency glow discharge time-of-flight mass spectrometry

Although glow discharge mass spectrometry (GDMS) is best known for its utility in trace element analysis, recent work demonstrates that the technique can also provide chemical speciation information. Previous reports outline approaches for the direct speciation of chromium and manganese oxides utilizing GDMS. As that work illustrates, different approaches to speciation are needed depending on the metal oxide under study. The present work extends the application of this technique to the direct speciation of three iron oxide species in solid state samples. The appropriate adjustment of parameters such as sampling distance, temporal regime, discharge gas pressure, pulse frequency, and duty cycle is essential to enable such speciation. For the iron oxides, species specific variations in ratios between Fe+ and FeOH+ signal intensities provide the ability to discriminate between FeO, Fe2O3, and Fe3O4. Iron–oxygen cluster generation correlates with oxygen abundance in the original sample as seen in these comparisons.

Selection of Discharge Gases for Analysis of Aluminum Alloys by Glow Discharge Mass Spectrometry

Analysis of aluminum (Al) alloys was carried out using helium and argon/glow discharge mass spectrometry (He/GD-MS, and Ar/GD-MS). The relative sensitivity factors RSFX, Al over the Al matrix used for GD-MS quantitative analysis were determined using six commercial Al alloy standard reference materials. The analytes comprise 15 elements containing in Al alloys: beryllium (Be), magnesium (Mg), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), strontium(Sr), tin (Sn), lead (Pb), and bismuth (Bi). A glow discharge cell for disk samples was used. A 12-mm internal diameter sample mask made from Ta was employed as the part of the anode. The discharge current was 3-mA for both of discharge gas. Large dispersion was observed in several obtained RSF values, resulting from insufficient validity of certified values of some elements such as Be. Nevertheless, the dispersion in RSF values was 8% or less as RSD for most of the analytes. The Ar/glow discharge was suitable for analysis of Al alloys because the RSF-values almost were better than those obtained by measurement using the He/glow discharge. Values obtained by GD-MS for a practical Al alloy A356 well agreed with the chemical analysis result, from alloying elements like Si, minor components such as Mg and Ti, to trace elements of parts per million level. Moreover, regarding the accuracy of GD-MS analysis, minor components such as Mg, Ti, and Fe can be determined within about 2% accuracy as RSD, and trace elements below a single mass ppm within 5%, except for Cr (RSD: 24.4%), Ni (9.8%), and Sn (13.3%). We established an eco-friendly analytical method without acid-decomposition by chemical reagents.

Improvement of CdMnTe Detector Performance by MnTe Purification

ABSTRACTResidual impurities in manganese (Mn) are a big obstacle to obtaining high- performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material’s purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te that has a very high solubility. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiple refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.

Refining of metallurgical silicon by directional solidification

Abstract The directional solidification of a typical and a previously refined metallurgical silicon was carried out in a vertical Bridgman furnace. The mold velocity out of the hot zone of the furnace changed from one experiment to another in the range between 5 and 110 μm s−1. Samples were extracted from the cylindrical ingots obtained in the experiments to investigate the effects of the mold velocity on the micro and macrostructures and on the concentration profiles of impurities along the ingots. At the lowest mold velocity, the macrostructures consist of columnar grains oriented approximately parallel to the ingot axis. As velocity increases, grains become thinner and more inclined in the radial direction. Precipitated particles containing Si, Fe, Al, and Ti are observed at the top of all ingots and, as the mold velocity increases, they are also seen at the ingot bottom and middle. The concentration profiles of several impurities have been measured along the ingots by inductively coupled plasma atomic emission spectrometry (ICP), indicating an accumulation of impurities at the ingot top. Consequently, the bottom and middle of the ingots are purer than the corresponding metallurgical silicon from which they solidified. Slices from the ingot bottom have also been analyzed by the glow discharge mass spectrometry technique (GDMS), allowing measurement of impurity concentrations that were below the quantification limit of the ICP. The purification effect and the accumulation of impurities at the ingot top are more pronounced as the mold velocity decreases. In the ingots obtained from the typical metallurgical silicon at the lowest mold velocities (5 and 10 μm s−1), except for Al, all impurities are in concentrations below an important maximum limit for the feedstock of solar grade silicon. At the same mold velocities, the concentrations of Fe, Ti, Cu, Mn, and Ni measured at the bottom of the ingots obtained from both types of metallurgical silicon (typical and previously refined) are even below some limits suggested directly for solar grade silicon.