Glow Discharge Mass Spectrometry Research Articles

Determination of trace elements in high purity alumina powder by helium enhanced direct current glow discharge mass spectrometry

Trace impurities in high purity alumina powder were determined by fast flow direct current glow discharge mass spectrometry (GD-MS). The non-conductive samples were prepared with high purity graphite powder and used as a sample binder and as a secondary cathode. To improve the sensitivity of the GD-MS analysis, helium was introduced as an additional glow discharge gas to argon plasma. The quantification results of the GD-MS measurement were calculated by external calibration with matrix matched certified reference materials. The GD-MS results for the determination of Na, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn and Ga in the alumina samples agreed well with the certified values of a reference material and the results of chemical analysis using wet sample digestion with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The GD-MS analysis is a rapid analysis technique to determine trace elements in non-conductive alumina to below mg·kg−1 levels.

Fourth round robin report—trace elements in Cr-Mo-V steel weld metal

Three 2-1/4 Cr-1 Mo-V submerged arc weld metals were produced with varying levels in the vicinity of 1 part per million (ppm) of Pb and Bi. Nine laboratories participated, of which five employed inductively coupled plasma-mass spectrometry (ICP-MS) for analysis, two used glow discharge-mass spectrometry (GD-MS) for analysis, one used atomic absorption (AA) for analysis, and one used inductively coupled plasma-optical emission spectrometry (ICP-OES) for analysis. ICP-OES was unable to detect Pb or Bi at the levels of the samples. ICP-MS reproduced measurements around 1 ppm of Pb with standard deviation of 0.2 ppm or less and reproduced measurements around 1 ppm or less of Bi with standard deviation of 0.1 ppm or less. The GD-MS results were within two standard deviations of the ICP-MS average results with one minor exception. The AA results for Pb were more than two standard deviations higher than the ICP-MS average results, but the AA results for Bi were within two standard deviations of the ICP-MS average results.

Does asymmetric charge transfer play an important role as an ionization mode in low power–low pressure glow discharge mass spectrometry?

We report results of comprehensive studies using the Nu Instruments Astrum high-resolution glow discharge mass spectrometer (GD-MS) and optical emission spectrometry (OES) to investigate the relative importance of discharge mechanisms, such as Penning ionization (PI) and asymmetric charge transfer (ACT), at low-power/low-pressure discharge conditions. Comparison of the ratios of the ion signals of each constituent element to that of the plasma gas shows that for oxygen, the ratio in krypton is more than ten times higher than in argon (oxygen ground state ions are produced by Kr–ACT). For many elements, the ratios are very similar but that for tungsten is higher with krypton, while for iron, the reverse holds. These effects are linked to the arrangement of ionic energy levels of the elements concerned and the resulting relative importance of ACT and PI. The GD-MS and GD-OES results have shown that the ACT process can play an important role as the ionization mode in low-power/low-pressure discharges. However, OES results have shown that the magnitude of change in spectral intensities of elements studied are dependent on the discharge conditions.

Study on the Impurity Effect in the Realization of Silver Fixed Point

The application of a thermal analysis model to estimate the temperature depression from the ideal fixed-point temperature is important, especially when the chemical analysis of the sample in a cell is insufficient or the cell might have been contaminated during fabrication. This study extends previous work, on thermal analysis with the tin point, to an investigation of the impurity dependence of the silver-point temperature. Close agreement was found between the temperature depression (\(-0.36\) mK) inferred from the thermal analysis of the measured fixed-point plateau and the temperature depression (\(-0.32\) mK) inferred using the sum of individual estimates (SIE) method with an impurity analysis based on glow discharge mass spectrometry. Additionally, the results of the thermal analysis manifest no significant dependence on the rate of solidification, and the scatter of observed gradients was within 0.36 mK among five plateaux with different temperature settings of the furnace. Although the results support the application of both the SIE method and thermal analysis for the silver point, further experiments with cell-to-cell comparisons linked to thermal analysis, a study of the thermometer-furnace systematic effects, the oxygen effect, and the locus of the freezing plateau should be investigated to reach a firm conclusion.

Determination of relative sensitivity factors of elements in high purity copper by doping-melting and doping-pressed methods using glow discharge mass spectrometry

The calibration samples were prepared from high pure copper powder doped with standard solutions of graduated and defined concentration. And then a part of them was melted into bulks and another was pressed to tablets.

Two-dimensional elemental mapping using glow discharge mass spectrometry

We present a simple modification in the design of glow discharge mass spectrometry (GD-MS) system that allows for two-dimensional (2D) elemental imaging.

Electrorefining of Silicon Using Molten Salt and Liquid Alloy Electrodes

A new Si refining process, which employs molten salt electrolysis and precipitation steps, is proposed and tested. In this process, impure Si is added to a Cu-Si liquid alloy anode, and the electrorefining of Si is conducted using an Al-Si liquid alloy cathode in a fluoride-based molten salt. From the obtained Si-enriched Al-Si alloy, purified Si is obtained by precipitation. A glow discharge mass spectrometry analysis revealed that the proposed process can effectively remove the dominant impurities such as Fe, Mn, Ti and V from metallurgical grade Si (98–99% purity). A preliminary electrolysis using Si cells recovered from a commercial photovoltaic module, of which the dominant impurities are Ag, Al and Na, showed that the present process is also applicable for Si recycling from waste photovoltaic modules.

Glow Discharge Mass Spectroscopy Study of Ion Concentrations of Joints in Anodic Bonding of Borosilicate Glass to Ultrathin Silicon

Glow Discharge Mass Spectroscopy Study of Ion Concentrations of Joints in Anodic Bonding of Borosilicate Glass to Ultrathin Silicon

Research on the removal of impurity elements during ultra-high purification process of terbium

Ultra-high purification of terbium (Tb) by vacuum distillation and external getter was investigated. More than 20 kinds of impurity elements were analyzed by glow discharge mass spectrometry (GDMS) and inert gas analysis (IGA). The analysis results show that total impurities decrease from 1114 ppm to 63 ppm. High volatile metallic impurities such as Mg, Ca, Mn, Zn, and Tm can be reduced effectively after distillation. The oxygen (O) concentration can be decreased to 1.8 ppm after deoxidation process, which currently is one of the best results in the contemporary studies. The chemical driving force for deoxidation has been calculated in this paper. The different deoxidation results of Tb metal with various purity have been discussed in detail using the secondary ion mass spectroscopy (SIMS). Finally, a ultra-high purity Tb with low concentration of O can be obtained through vacuum distillation and external getter method.

Synthesis of Si and tin-doped Si powders via gas-phase sodium reduction for Li-ion batteries

Pure silicon nano-powder was successfully synthesized via gas-phase sodium reduction of silicon tetrachloride, exhibiting 100% conversion of the reactants and achieving >95% yield of the final product. The interactions of the process conditions and tin-doping with the particle morphology were investigated. The produced powders were analyzed by nitrogen adsorption, transmission and scanning electron microscopy, X-ray diffraction, inert gas fusion analysis and glow discharge mass spectroscopy. The washed polycrystalline silicon particles had a BET surface area in the range of 23–44m2/g. The silicon aciniform aggregates consisted of relatively homogeneous primary particles in the range of 20–100nm. The silicon was protected by a 2–3nm thick passivation layer established during the washing step resulting in an oxygen content of less than 3wt.%. Electrochemical testing demonstrated a high inherent capacity for the pure Si powders. The initial capacity and 1st cycle charge efficiency of Si-containing anode electrodes was dependent on the initial powder surface area. The highest capacity was achieved for Si powders with intermediate BET surface area of 28.5m2/g and cells with this anode material delivered capacity of 2651mAh/g (normalized to Si) and 82.4% efficiency at first charge.

Investigation of the flickering of La2O3 and ThO2 doped tungsten cathodes

Short-arc lamps are equipped with tungsten electrodes due to their ability to withstand a high thermal load during operation. Nominal currents of more than one hundred amperes lead to a cathode tip temperature near the melting point of tungsten. To reduce the electrode temperature and, thereby, to increase the maintenance of such lamps, ThO2 or tentatively La2O3 are added to the electrode material. They generate a reduced work function by establishing a monolayer of emitter atoms on the tungsten surface. Emitter enrichments on the lateral surface of doped cathodes are formed. They are traced back to transport mechanisms of emitter oxides in the interior of the electrode and on the electrode surface in dependence of the electrode temperature and to the redeposition of vaporized and ionized emitter atoms onto the cathode tip by the electric field in front. The investigation is undertaken by means of glow discharge mass spectrometry, scanning electron microscope images, energy dispersive x-ray spectroscopy, and through measurements of the optical surface emissivity. The effect of emitter enrichments on the stability of the arc attachment is presented by means of temporally resolved electrode temperature measurements and by measurements of the luminous flux from the cathode-near plasma. They show that the emitter enrichments on the lateral surface of the cathode are attractive for the arc attachment if the emitter at the cathode tip is depleted. In this case, it moves along the lateral surface from the cathode tip to sections of the cathode with a reduced work function. It induces a temporary variation of the cathode tip temperature and of the light intensity from the cathode-near plasma, a so-called flickering. In particular, in case of lanthanated cathodes, strong flickering is observed.

Effects of reaction temperature on the synthesis of high purity silicon carbide powder

High purity silicon carbide powder for growing semi-insulating silicon carbide single crystal was synthesised using high purity carbon and silicon powder. The effects of reaction temperature on the phase composition, particle size and the production yield were discussed. The results showed that with increasing the reaction temperature, the phase transition from β-silicon carbide to α-silicon carbide was found. Moreover, the particle size and the production yield were first increased with raising the reaction temperature and then decreased when the temperature was higher. The results of glow discharge mass spectroscopy indicated that the synthesised silicon carbide powder can meet the requirements for semi-insulating silicon carbide single crystal growth. Finally, the semi-insulating 4H-SiC single crystals were grown using silicon carbide powder which was synthesised in our laboratory.

Methodology to analyse small silicon samples by glow discharge mass spectrometry using a thin wafer mask

Glow discharge mass spectrometry (GDMS) is widely used for trace element analysis of bulk solid samples. The geometry of the GD source limits the minimum size of the sample, which for the instrument used in this work (ThermoElementGD) is 20mm in diameter. From time to time, there is the need to analyse smaller samples with this technique, and we present here a methodology to analyse samples of 9–20mm diameter through the use of thin masks.Thin masks have been previously used mostly as secondary cathode for the analysis of non-conducting materials, with hole size smaller than the area of the glow discharge. The use of masks in this work includes the following customization:•The choice of highly-pure Si as mask material, to decrease the chance of interferences with the Si samples.•The use of a hole in the mask of the same size as the discharge area. This implies that the mask material is not sputtered, thus decreasing chances for contamination from the mask itself.

Changes of tribological properties of Inconel 600 after ion implantation process

Abstract Commercial Inconel 600 nickel-chromium alloy was implanted with nitrogen, titanium, chromium, copper with tin (as bronze components) and yttrium ions to doses ranging from 1.6e17 to 3.5e17 cm−2. The aim of this research was to investigate the properties of the modified alloy in the context of its application in foil bearings. The virgin and the treated samples were tribologically tested and examined by Scanning Electron Microscopy, Glow Discharge Mass Spectrometry and Energy Dispersive Spectroscopy. The technological studies were preceded by modelling of concentration values of the introduced elements. The results obtained with the use of ion implantation are discussed. There are two advantages which should be highlighted: good agreement in modelling and experimental results of depth profiles of implanted ions, wear resistance improvement of Inconel 600 surface by implantation of copper and tin ions. The tribological tests indicate that abrasion and corrosion are the predominant mechanisms of surface wear.

Cz-Silicon Produced from Solar Grade and Recycled Materials. Part I: Bulk Properties and Formation of As-Grown Defects

The current paper is the first of two, investigating the properties of Czochralski-silicon (Cz-silicon) materials and solar cells produced with recycled and compensated silicon materials. In this work, impurity levels in two experimental Cz-silicon ingots were characterized by glow discharge mass spectroscopy and FTIR. The combined effects of these impurities on recombination properties were investigated by photoluminescence imaging and compared to bulk properties of a reference ingot. Ring pattern distribution of as-grown micro-defects in the ingots, related to elevated carbon and oxygen levels, were delineated based on the results of two steps of dry oxidation. Moreover, the mechanism of defect formation in the experimental Cz-Si during solidification and oxidation is elaborated in light of thermodynamic theories. Meanwhile, the positive effect of phosphorus in compensated feedstock is discussed in relation to the minority carrier lifetime based on the quasi-steady-state photoconductance results, as well as on the restricted formation of oxygen-related defects during solidification by analyzing samples after oxidation and copper decoration.

The use of matrix-specific calibrations for oxygen in analytical glow discharge spectrometry.

The performance of glow discharge optical emission spectroscopy and mass spectrometry for oxygen determination is investigated using a set of new conductive samples containing oxygen in the percent range in three different matrices (Al, Mg, and Cu) prepared by a sintering process. The sputtering rate corrected calibrations obtained at standard conditions for the 4 mm anode (700 V, 20 mA) in GD-OES are matrix independent for Mg and Al but not for Cu. The importance of a “blue shifted” line of oxygen at 130.22 nm (first reported by Köster) for quantitative analyses by GD-OES is confirmed. Matrix-specific calibrations for oxygen in GD-MS are presented. Two source concepts—fast flow (ELEMENT GD) and low gas flow (VG9000)—are evaluated obtaining higher sensitivity with the static flow source. Additional experiments using Ar-He mixtures or μs pulsed GD are carried out in ELEMENT GD aiming to improve the oxygen sensitivity.

Determination of major nonmetallic impurities in magnesium by glow discharge mass spectrometry with a fast flow source using sintered and pressed powder samples.

Fast flow glow discharge mass spectrometry with a Grimm-type ion source providing a high sputter rate was used for the determination of major nonmetallic impurities in magnesium. The analytical signal was found to be strongly influenced by the electrical discharge parameters. For calibration by standard addition, synthetic standard samples were produced in two different ways-namely, by pressing and by sintering doped metal powders. The observed sensitivity of the calibration curves was shown to depend on the particle size of the powder. For the magnesium powders, the mass fractions of oxygen, nitrogen, boron, and silicon were determined to be about 0.01 kg·kg(-1) (relative standard deviation approximately 10-20 %), 2,700 mg·kg(-1), 150 mg·kg(-1), and 300 mg·kg(-1), respectively.

On copper diffusion in silicon measured by glow discharge mass spectrometry.

Copper contamination occurs frequently in silicon for photovoltaic applications due to its very fast diffusion coupled with a low solid solubility, especially at room temperature. The combination of these properties exerts a challenge on the direct analysis of Cu bulk concentration in Si by sputtering techniques like glow discharge mass spectrometry (GDMS). This work aims at addressing the challenges in quantitative analysis of fast diffusing elements in Si matrix by GDMS. N-type, monocrystalline (Czochralski) silicon samples were intentionally contaminated with Cu after solidification and consequently annealed at 900 °C to ensure a homogeneous distribution of Cu in the bulk. The samples were quenched after annealing to control the extent of the diffusion to the surface prior to the GDMS analyses, which were carried out at different time intervals from within few minutes after cooling onward. The Cu profiles were measured by high-resolution GDMS operating in a continuous direct current mode, where the integration step length was set to ∼0.5 μm over a total sputtered depth of 8-30 μm. The temperature of the samples during the GDMS analyses was also measured in order to evaluate the diffusion. The Cu contamination of n-type Si samples was observed to be highly material dependent. The practical impact of Cu out-diffusion on the calculation of the relative sensitivity factor (RSF) of Cu in Si is discussed.

Studies of rare earth elements to distinguish nephrite samples from different deposits using direct current glow discharge mass spectrometry

Nephrite is an interesting gemstone of wide versatility that is used for ritual objects, decoration, utilitarian objects, carving or jewellery around the world. It is necessary to demonstrate a possible relationship between the concentrations of characteristic elements and differences in the quality or deposit. In this study, direct current glow discharge mass spectrometry (dc-GD-MS) was used to determine the rare earth elements (REEs) of 14 nephrite samples from different deposits by using a tantalum (Ta) pin for the electrical connection, and this method has successfully overcome interferences in the REE analyses. After the optimization of discharge conditions, the characteristics of REEs were studied for nephrite minerals obtained from different deposits. Principal component analysis using REEs and other minor and trace elements successfully separated some nephrites from specific deposits. The dc-GD-MS was an effective tool for the classification of nephrites from different deposits.

Assignment of purity to primary metal calibrants using pin-cell VG 9000 glow discharge mass spectrometry: a primary method with direct traceability to the SI international system of units?

A measurement model based on the use of a pin-cell glow discharge source coupled to a VG 9000 sector field mass spectrometer (GD-MS) for the assignment of purity of high-purity metals, i.e., mass fraction of metal matrix, w(M), is presented. A mass balance approach to the calculation requires the determination and summation of impurity mass fractions of all extraneous elements present, including non-metals and gases. It is posited that a primary method of measurement can be devised to yield direct traceability of results to the SI. The major source of uncertainty in the traceability chain stems from the need to adjust the initially estimated quantity values of each impurity element by a relative sensitivity factor ‘influence quantity’ , derived from ab initio calculations, and validated through comparison with those derived through use of Certified Reference Materials. It is argued that the method is sufficiently well understood that a measurement equation can be formulated for which all parameters are measured in terms of SI units; that all contributions to uncertainty of measurement can be quantitatively evaluated, underpinning the metrological traceability; and that the performance of GD-MS in CCQM key and pilot comparisons of trace elements in complex metal matrices is in conformance with claimed capabilities. The applicability of the approach to metals in the 3N to 7N range of purity shows that fit-for-purpose relative expanded uncertainties of 0.5% to 0.000 05% can be conservatively achieved for w(M). Presentation of various instrument calibration scenarios vis-à-vis impact on SI traceability of results is also undertaken with a view to eliciting further discussion of this concept within the metrological community.