Glow Discharge Mass Spectrometry Research Articles

Combustion Methods for Measuring Low Levels of Carbon in Nickel, Copper, Silver, and Gold

Laboratory studies and a literature search indicate that there is no definitive procedure for combustion analysis of low levels of carbon in Cu, Ag, and Au. Literature data disagree by one to two orders of magnitude for solubility of carbon in Cu, near the melting point. Data for Ag and Au are very limited. This study develops a procedure for combustion analysis of ppm levels of carbon in high-purity Ni, Cu, Ag, and Au samples. For comparison, each sample is measured with glow discharge mass spectrometry. The study begins with Ni, as the procedure for this material is fairly well established. For the other metals, an optimum accelerator and sample-to-accelerate weight ratio is developed. Fine particle copper is a suitable accelerator for Cu and Ag samples, and also shows potential for Au samples

Comparison of Characterization Techniques for Measurements of Doping Concentrations in Compensated n-type Silicon

Nowadays, compensated silicon (Si) is used in photovoltaic (PV) processes, whether it is through intentional co-doping of resistivity-adjusted Czochralski ingots for high efficiency n-type Si solar cells, as a result of alternative Si purification processes for the production of low-cost Si feedstock, or as a result of recycling end-of-life materials. Whatever the origin of the compensated Si, the doping concentrations need to be accurately and quickly characterized in order to control such processes. In this work, a rapid and highly sensitive characterization technique based on low temperature Hall Effect measurements is described in scientific details and compared to three well-established chemical methods: Glow Discharge Mass Spectrometry (GDMS), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS), and Secondary Ion Mass Spectrometry (SIMS). The characterized samples were extracted from the n-type top part of a casted solar grade Si ingot. A very good agreement is observed between the dopants densities extracted from the electrical method and from the standard methods. With the advantage of a very low detection limit combined with a short measurement time, the advanced Hall Effect technique is promising for the rapid and accurate characterization of dopant concentrations in compensated Si.

Structural and Chemical Characterization of Li-Ion Batteries

Lithium ion batteries have improved rapidly in the last 10 years to become the main power source in portable electronics, telecommunications, and large capacity applications such as in electric vehicles (EV). Ongoing improvements in characterization techniques must also meet industry, regulatory and consumer needs as battery manufacturers and end-users demand higher battery efficiencies, lower cost, and most importantly, safety. At Evans Analytical Group (EAG, Inc.), we provide a suite of techniques suitable for both the structural and chemical analysis of Li-ion batteries. Both scanning and transmission electron microscopy (SEM and TEM) are used to provide the thickness and microstructure of the various layers in the battery. Ion milling techniques are used to preserve the integrity of the sample to assure an accurate representation of the original state of the battery materials. This is essential in order to properly understand process development or battery failures. TEM combined with X-Ray Diffraction (XRD) can also be used to analyze the phase transformations associated with the diffusion of Li-ions. Additionally, the thickness of the thin SEI layer caused by electrode-electrolyte interfacial reactions can only be visualized by TEM. Degradation mechanisms of the battery materials can be analyzed with surface analysis techniques such as X-ray photoelectron spectroscopy (XPS) to detect chemical state information and gas chromatography (GCMS) techniques to detect volatile components that can lead to swelling of the battery. These techniques along with Raman and infrared spectroscopy (FTIR), and Glow Discharge Mass Spectrometry (GDMS) can detect the organic and inorganic species present in the battery, including any impurities that may be present. GDMS is commonly used for purity certification of cathode materials such as LiCoO2, LiFePO4, and LiCoMnNiOx .Inductively coupled optical emission techniques (ICP-OES) can be used to determine the Li/metal ratio to within a 1% uncertainty, which is essential for tuning the cycling stability of Li-ion batteries. In this presentation we will demonstrate the multi-disciplinary approach of using these various techniques and the importance of proper sample preparation for accurate analyses of Li-ion batteries. This approach enhances the value of the information obtained and can accelerate product development.

Thermally induced native defect transform in annealed GaSb**Project supported by the National Natural Science Foundation of China (Grant Nos. 61474104 and 61504131).

Undoped p-type GaSb single crystals were annealed at 550–600 °C for 100 h in ambient antimony. The annealed GaSb samples were investigated by Hall effect measurement, glow discharge mass spectroscopy (GDMS), infrared (IR) optical transmission and photoluminescence (PL) spectroscopy. Compared with the as-grown GaSb single crystal, the annealed GaSb samples have lower hole concentrations and weak native acceptor related PL peaks, indicating the reduction of the concentration of gallium antisite related native acceptor defects. Consequently, the below gap infrared transmission of the GaSb samples is enhanced after the thermal treatment. The mechanism about the reduction of the native defect concentration and its influence on the material property were discussed.

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.