A method for signal enhancement utilizing stacked magnets was introduced into high-resolution radio frequency glow discharge-mass spectrometry (rf-GD-MS) for significantly improved analysis of inorganic materials. Compared to the block magnet, the stacked magnets method was able to achieve 50–59% signal enhancement for typical elements in Y2O3, BSO, and BTN samples. The results indicated that signal was enhanced as the increase of discharge pressure from 1.3 to 8.0 mPa, the increase of rf-power from 10 to 50 W with a frequency of 13.56 MHz, the decrease of sample thickness, and the increase of number of stacked magnets. The possible mechanism for the signal enhancement was further probed using the software “Mechanical APDL (ANSYS) 14.0”. It was found that the distinct oscillated magnetic field distribution from the stacked magnets was responsible for signal enhancement, which could extend the movement trajectories of electrons and increase the collisions between the electrons and neutral particles to increase the ionization efficiency. Two NIST samples were used for the validation of the method, and the results suggested that relative errors were within 13% and detection limit for six transverse stacked magnets could reach as low as 0.0082 μg g–1. Additionally, the stability of the method was also studied. RSD within 15% of the elements in three nonconducting samples could be obtained during the sputtering process. Together, the results showed that the signal enhancement method with stacked magnets could offer great promises in providing a sensitive, stable, and facile solution for analyzing the nonconducting materials.

Development of lithium sulfur (Li–S) batteries with high Coulombic efficiency and long cycle stability remains challenging due to the dissolution and shuttle of polysulfides in electrolyte. Here, a novel additive, carbon disulfide (CS2), to the organic electrolyte is reported to improve the cycling performance of Li–S batteries. The cells with the CS2-additive electrolyte exhibit high Coulombic efficiency and long cycle stability, showing average Coulombic efficiency >99% and a capacity retention of 88% over the entire 300 cycles. The function of the CS2 additive is 2-fold: (1) it inhibits the migration of long-chain polysulfides to the anode by forming complexes with polysulfides and (2) it passivates electrode surfaces by inducing the protective coatings on both the anode and the cathode.Keywords: additive; carbon disulfide; electrolyte; lithium sulfur battery; SEI;

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.

•A dc-GD-MS was applied for analysis of doping elements in synthetic crystals.•The two methods could sustain stable discharge and enhance the stability.•Ta carrier method was more effective to analyze rare earth elements.•The two methods could be used together to make up for the deficiency.Direct current glow discharge mass spectrometry (dc-GD-MS) was applied for the determination of doping elements in synthetic crystals. To get stable discharge, the surface coating method and tantalum carrier method were used to support the sputtering and ionization of samples respectively. For the analysis of BaF2, Y3Al5O12 (YAG), Bi4Si3O12 (BSO), La3Ga5SiO14 (LGS), CsI and Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), the stable discharge current and the matrix signals were investigated by using these two methods. While for the analysis of CaF2 and γ-Al2O3, the tantalum carrier method could sustain much stable discharge to achieve fine intensity of matrix elements compared to the surface coating method. Furthermore, two Y3Al5O12 (YAG) samples were also studied by inductively coupled plasma optical emission spectrometer (ICP-AES) to validate the precision, accuracy and reproducibility of these two methods. The results suggested that the dc-GD-MS would be a good choice to determine the doping elements in synthetic crystals by these two methods.

A surface coating method was developed to analyze some non-conducting materials using the pin cell of a direct current glow discharge mass spectrometer (dc-GD-MS). As the materials were non-conducting there were many problems associated with sustaining a dc glow discharge, and this could be overcome by coating the surface with a very thin layer of conducting material. During the sample preparation process the melted indium was coated manually onto the surface of the sample, thus supporting the sputter process and causing the sample to be sputtered and ionized for analysis. After optimization of the plasma conditions, the prepared samples could be analyzed directly by dc-GD-MS with satisfactory detection limits, stability and reproducibility. Two NIST standard reference materials were used to validate the precision, accuracy and reproducibility of this method. The results showed that this method could avoid grinding, sustain the relatively stable discharge and enhance the stability of signals compared to the method of using a cathode made from indium pin rolled in the sample powder.

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.Graphical abstractHighlights► GD-MS analysis was used to study nephrite minerals of different deposits. ► Two types of nephrite minerals were separated by Cr, Co and Ni elements. ► Nephrite minerals from some specific deposits had their typical elements.

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.

A surface coating method was developed to analyze some non-conducting materials using the pin cell of a direct current glow discharge mass spectrometer (dc-GD-MS). As the materials were non-conducting there were many problems associated with sustaining a dc glow discharge, and this could be overcome by coating the surface with a very thin layer of conducting material. During the sample preparation process the melted indium was coated manually onto the surface of the sample, thus supporting the sputter process and causing the sample to be sputtered and ionized for analysis. After optimization of the plasma conditions, the prepared samples could be analyzed directly by dc-GD-MS with satisfactory detection limits, stability and reproducibility. Two NIST standard reference materials were used to validate the precision, accuracy and reproducibility of this method. The results showed that this method could avoid grinding, sustain the relatively stable discharge and enhance the stability of signals compared to the method of using a cathode made from indium pin rolled in the sample powder.