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Vanadium nitride (VN) serves as a versatile material in various applications such as electrodes, ceramics, catalysts, and alloy components owing to its robust electrical performance, favorable stability, and high hardness. However, conventional VN synthesis methods require long soaking times and high temperatures. This study investigates a method wherein VxCypowder was soaked in an N2atmosphere for a shorter period of time at a lower temperature to produce high-quality VN particles. The mechanism underlying this process was investigated via thermodynamic analyses, ab initio molecular dynamics (AIMD) simulations, and experimental studies. Thermodynamic analysis validates the thermodynamic feasibility of the reactions between VxCyand N2to produce VN, while the atomic-level interactions between VxCy, N2, and surplus C atoms were comprehensively elucidated. By analyzing the two systems, it was discovered that the surplus C promoted the combination of N2molecules with V atoms to form V–N in shorter AIMD simulation durations. Surplus C increased the chance of N2molecules and V atoms to contact, similar to a catalytic effect, by activating N2molecules to decompose and further reacted with V atoms to form VN. According to the experimental results, high-quality VN particles were formed at a heating temperature of 1323 K and soaking period of 90 min. Field-emission scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS), particle size distribution analysis, and X-ray diffraction (XRD) were used to characterize the final product. The O and N contents were measured by an O/N analyzer at 0.11% and 17.4%, respectively. Accordingly, a C/S analyzer measured the C content at 3.92%. These analyses indicate that high-quality VN can be obtained by the VxCynitridation in N2atmosphere.

In this study, a novel two-stage vacuum distillation method was proposed to refine crude indium to prepare refined indium. Low-temperature distillation (1223K, holding time of 3h) and high-temperature distillation (1473K, holding time of 5h) were conducted under a system pressure of 7 × 10−3Pa to successfully purify crude indium (99 wt%) to refined indium (99.995 wt%). This strategy can replace the traditional electrolytic process for the clean production of refined indium and achieve the goals of environmental protection. The vapor-liquid equilibrium (VLE) values of indium-based binary alloys were calculated using the molecular interaction volume model (MIVM), and a VLE phase diagram was drawn. Optimal temperatures of 1173K for low-temperature and 1373K for high-temperature distillation were determined based on the VLE phase diagram, and good purification was achieved. Moreover, this study reveals the migration distribution pattern of typical impurity elements (e.g., Tl and Sn) in crude indium in the low and high-temperature distillation sections, further improving the refining effect. Notably, the combination of MIVM simulations and experiments can obtain optimal experimental parameters for segmental vacuum distillation and further help to avoid the waste of raw materials and energy caused by pre-experiments, realizing the clean and efficient production of refined indium.

Vacuum volatilization is a clean and efficient method for metal purification, alloy separation, and comprehensive recovery of secondary resources. The evaporation kinetics of In and In–Sn alloys were investigated to better understand the evaporation mechanism during the vacuum volatilization of In. The evaporation rates of the In and In–Sn alloys at 1173–1373 K and 5 Pa increased significantly with increasing temperature in accordance with the equation ω = e(a+b∙T). The evaporation rates at 1323 K and 5 Pa decreased with increasing crucible depth in accordance with the equation ω = a2+(a1-a2)/(1+e(h-b)/c). For In and In–Sn, the total mass-transfer coefficients of In were obtained at different temperatures and crucible depths. A theoretical kinetic model of In was established and limiting links were obtained vacuum volatilization of In and In–Sn.

The recovery of tellurium and bismuth from bismuth telluride waste is of great significance in improving the utilization levels of renewable resources, protecting the ecological environment and alleviating the problem of resource shortages. In this paper, tellurium and bismuth were recovered from bismuth telluride waste by selective sulfidation–vacuum volatilization. The Gibbs free energy, phase diagram and thermodynamic equilibrium diagram for the core reaction were calculated and analyzed to determine the possible reactions and the conditions required for the stability of bismuth telluride during the sulfidation process. After calculating the saturated vapor pressures, it was concluded that tellurium and bismuth sulfide could be separated by vacuum volatilization. The thermogravimetric analyses and differential scanning calorimetry were then used to analyze the reaction between bismuth telluride and sulfur. The results indicated that the temperature range for the sulfidation reaction should be 491–620 K. The volatilization temperature of tellurium should be greater than 695 K. The evaporation kinetics for tellurium and bismuth sulfide showed that the evaporation rate of tellurium was much higher than that of bismuth sulfide. Furthermore, experiments were conducted to verify the reliability of the theoretical analysis, and these were in good agreement with the thermodynamic and kinetic results. The direct yields of tellurium and bismuth were 99.65% and 99.49%, respectively. These results confirmed that the selective sulfidation-vacuum volatilization method is a feasible alternative for recovery of tellurium and bismuth from bismuth telluride waste.

The Kroll process is currently the only effective method in industry to produce sponge titanium with a low-oxygen concentration (500 ppm). However, it has several limitations, such as a long processing time, low efficiency, and high energy consumption, resulting in the high production cost of titanium. To reduce the production cost, a method to prepare low-oxygen titanium powder by magnesiothermic reduction of TiO2in KCl–MgCl2–YCl3molten salt was designed. The thermodynamic calculation results showed that it was feasible to prepare titanium powder by the magnesiothermic reduction of TiO2at 1073, 1173, and 1273 K. In addition, the deoxidation limits of Mg under Mg/MgCl2/YCl3/YOCl equilibrium were 3, 12, and 38 ppm at 1073, 1173, and 1273 K, respectively. The experimental results showed that titanium powder with a high oxygen concentration of approximately 10,000 ppm was obtained when the reduction was conducted in KCl–MgCl2molten salt (i.e., the activity of YCl3(aYCl3) was 0). Low-oxygen titanium powder was prepared with the addition of YCl3in the molten salt and formed yttrium oxychloride (YOCl) (TiO2(s) + 2Mg (l) + 2YCl3(l) = Ti (s) + 2MgCl2(l) + 2YOCl (s)). Moreover, at 1173 K, when the activity of YCl3(aYCl3) was 1, titanium powder with an oxygen concentration as low as 150 ppm was obtained. Based on these results, a novel process for preparing low-oxygen titanium powder was designed. The proposed process is fast and highly efficient, and its future application in industry is anticipated.

Circulation of Sb in an Sn refining system strongly affects the production process. In this study, an innovative multi-stage vacuum separation process was developed and successfully applied on an industrial scale. Our results indicate that Sn–Sb alloys can be completely separated by vacuum evaporation. In this study, we used single-factor experiments to investigate the effects of distillation temperature and time on several factors, such as the Sn content in the residue, Sb content in the volatile matter, separation rate, and direct recovery rate of Sb from high-Sb crude Sn. The purity of the obtained Sn and Sb products was above 99%, and the recovery rate of the metal was above 99% under the optimal distillation conditions of 1673 K and 150 min. In addition, we suggest that Sn volatilization occurs due to the presence of SbSn intermetallic compounds. A two-stage vacuum-separation process for high-Sb crude Sn was developed for industrial production. Continuous production data showed that the direct yields of Sn and Sb were 72.99% and 71.15%, respectively. The total power consumption of this process was as low as 1086 kWh/t, which is better than the corresponding parameters of other treatment processes.

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An important way to obtain PbS and FeS is the thermal decomposition of Jamesonite. However, the mechanism of PbS–FeS interaction is unknown. In order to explore the separation effect of PbS and FeS, thermodynamic calculation, dynamic simulation and vacuum distillation experiments were used to explore the interaction mechanism of PbS and FeS. The decomposition and volatilization temperatures of PbS and FeS were obtained by thermodynamic calculation. The difference of saturated vapor pressure indicates that there is a tendency of separation between them. The ab initio molecular dynamics method was used to calculate the density of states of PbS and FeS at different temperatures, indicating that the FeS(114) structure is more stable than the PbS(200) structure, and the Pb–S bond is easier to break than the Fe–S bond at the same temperature. The experimental results of vacuum distillation show that the volatilization temperature of PbS is much lower than that of FeS, and FeS can only volatilize into the gas phase at a higher temperature. The theoretical calculation method is consistent with the experimental results, which shows that the thermodynamic calculation and dynamic simulation methods are reliable in predicting the volatilization and separation of crystal structures. The interaction mechanism between PbS and FeS was explored from the theoretical point of view to provide theoretical guidance for vacuum distillation experiment.

In this study, the migration and distribution behaviors of Cu, Si, Fe, and Ti impurities in the process of preparing high-purity Al by zone melting under an argon atmosphere were investigated. The width of the molten zone during the experiment was determined as 40 mm, based on simulation calculation results. The influences of the travel speed of the molten area and number of zone melting times on the migration and distribution of the Cu, Si, Fe, and Ti impurities in the Al were experimentally demonstrated. The contents of the impurities Cu, Si, Fe, and Ti in the middle of the sample (i.e., 140 mm from the head end) were 0.9057, 0.8116, 0.1202, and 0.4237 ppm, respectively, when the travel speed of the molten area was 1.0 mm/min and with 15 times of zone melting. The contents of all the above impurities were reduced to the requirements of Chinese national standard and 99.9995% (i.e., 5N5) high-purity Al was obtained from 4 N Al by the zone melting method under the above optimal experimental conditions. The experimental results show that the effect of the number of zone melting times on the removal of the Cu, Si, and Fe impurities is more evident, and that these impurities are easier to separate than Ti. Therefore, high-purity Al with lower Cu, Si, and Fe contents can be obtained by optimizing the travel speed of the molten area and number of zone melting times.

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In this study, the authors discover the phenomenon of folding during the process of zone melting and purification of aluminum in a protective atmosphere, for the first time, and these surface folds tend to affect the purity and crystal growth of aluminum. Compared with zone melting purification under a protective atmosphere, when zone melting under vacuum is used, interfacial folding is reduced, and accordingly, the aluminum purity is improved and grain size is increased. Results show that when the vacuum is controlled at 0.1Pa, the aluminum samples show perfect purity and large crystal particles.

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Lead anode slime, which is produced by electrolytic refining of refined Pb, is a significant source of the rare metal Te. However, traditional methods for treating lead anode slime are characterized by complex processes, hazardous waste discharge, high energy consumption, repeated reduction and oxidation, and inefficient separation of Te. Therefore, a novel, green, and efficient vacuum gasification process for Te separation and enrichment was developed in this study. The optimal gasification temperature and time of Te volatilization were investigated using two-step, high-temperature and low-temperature vacuum distillation experiments; the system pressure was maintained at 5–15 Pa for both steps. Te (96.07%) in lead anode slime was separated using high-temperature vacuum gasification at 1173 K for 60 min and low-temperature vacuum gasification at 723 K for 45 min, yielding Te-rich volatiles with a 4.80% tellurium content. Te was enriched more than 16 times. Te existed as Te and TeO2in the tellurium-rich volatiles, making the volatiles an excellent raw material for further tellurium purification. This two-step vacuum gasification process provides theoretical guidance for effective and sustainable recovery of Te from lead anode slime with no waste gas or water, which meets the need for cleaner production methods in the metallurgical industry.

Traditional method for treatment of Pb–Ag alloy has disadvantages of a long metal production cycle, long process, and high energy consumption. Vacuum distillation has obvious advantages, such as a short flow, short production cycle, high direct yields of metal, and low cost. Kinetics is the key factor that determines production efficiency. Therefore, evaporation kinetics of Pb evaporation from pure Pb and Pb–Ag alloy has been investigated. The evaporation rate of pure Pb was experimentally determined as 0.044, 0.13 and 0.32 g cm−2·min−1at 1173 K, 1273 K and 1373 K, respectively. Pb evaporation from Pb–Ag alloy followed first order kinetics and the rate controlling step were mainly mass transfer in liquid which indicated that increasing the stirring of the melt during the production process can improve the removal efficiency of lead. In addition, some kinetic parameters were obtained such as the apparent activation energy of Pb evaporation from Pb–Ag alloy was 148.8 kJ mol−1, the mass transfer coefficient was 6.48 × 10−8, 1.90 × 10−7and 6.00 × 10−7 m s−1at 1173 K, 1273 K and 1373 K, respectively. The research enriches the Pb evaporation kinetic database and can provide theoretical guidance for the vacuum distillation of noble lead alloys. In addition, the research designs a set of alloy configuration and vacuum evaporation device with simple assembly and convenient operation which can be used for the research on vacuum evaporation kinetics of other non-ferrous metal alloy systems.

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Arsenic is commonly used in alloy materials and the semiconductor industry, and has promising applications. Arsenic and antimony have similar physicochemical properties, and their binding and separation mechanisms are unknown, thereby limiting the purification and preparation of arsenic. This study, from a microscopic perspective, reveals that arsenic and antimony covalently interact in alloys through a combination of thermodynamic analysis and molecular dynamics simulations. In addition, antimony as arsenic-antimony clusters enters the gas phase, and the diffusion coefficients of the clusters are in the order of As4>As3Sb>As2Sb2>AsSb3. A green and efficient vacuum sublimation-graded condensation process for arsenic purification is proposed based on the different diffusion coefficients to obtain the optimal process parameters. The coalescence of arsenic on a condenser was normally distributed. The removal rate of antimony in the most concentrated area of the condensate was 91.37% under the optimal conditions of 748 K, 60 min, and 10 Pa. Thus, the proposed method effectively solves the challenging problem of separating arsenic and antimony, and the study results provide theoretical support for purifying arsenic via vacuum sublimation.

A route is present for preparing porous titanium scaffolds with open and interconnected pore morphology through calcium thermal in-situ reduction of TiO precursor. Titanium and dioxide titanium powders, with ammonium carbonate as the space holder, were used to prepare porous precursor whose main phase is TiO by a sintering process. Then calcium vapor was conduced to reduce the precursor and CaO was removed by leaching to obtain porous titanium structures. The morphology, pore structure, phase analysis of porous titanium precursor and porous titanium scaffolds were investigated by means of XRD, SEM and EDS. The porosity was observed by Archimedes method. By this route, the porous titanium with multi-gradient pore sizes ranging from a few microns to several hundred microns was formed. The porous titanium is of multi-gradient pore size distribution of 100 μm bigger, 10 μm∼100 μm and 10 μm smaller. The micro-pores on the pore walls increases connectivity between the macro-pores throughout the porous titanium interior. The porous titanium obtained by this method has a porosity of 50–65% and a titanium content more than 99%.

Effective distribution coefficient (ke) plays an important role in zone melting purification but has never been systematically calculated as an important parameter. A novel analysis method for impurity separation separating from Al using determination of impurities (Si, Fe, Cu, Zn) content and calculation of kehas been investigated. Experimental results show that the impurity separation effect was significantly improved due to the keclosely approximating the equilibrium distribution coefficient (k0) via optimization of purification times and speed of the melting zone. When the times of purification were increased from 15 to 20 times, the kevalues of Si, Fe, Cu, and Zn at the sample (No. 3) were 0.603, 0.702, 0.364, and 0.502, respectively. Correspondingly, the removal rate of impurities of Si, Fe, Cu, and Zn increased by 6.25%, 1%, 10.49%, and 27.58%, respectively. The effect on the keof Cu and Fe is more significant at the sample (No. 3) when the melting zone speed is changed. The removal rates of Fe and Cu in the sample are 99.0% and 94.75% when the melting zone speed was 1/3 mm/min, and, correspondingly, the removal rates of Si and Zn were 81.7% and 88.51%, respectively. The Al content at sample position No. 3is more than 999994.59 ppm when the sample was purified 15 times at a speed of 0.5 mm/min, which meets the standard of 5N high purity aluminum.

In this study, metallurgical grade crude selenium (99.4%), comprehensively recovered from copper electrolysis anode slime, was purified to 99.992% through triple consecutive vacuum distillation (TCVD) on a laboratory scale. The actual evaporation rate and accommodation coefficient α of crude selenium were found to be 0.0231 g cm−2 min and 0.3236, respectively, at 523 K and approximately 4 Pa by a vacuum thermogravimetric furnace. Internal heat vacuum distillation equipment was employed in the purification experiments with a dynamic vacuum level of approximately 4 Pa. Detailed analysis of the initial and purified selenium was performed using inductively coupled plasma mass spectrometry (ICP-MS) to identify the 15 most common impurity elements. The analysis confirmed the reduction in the total impurity content from 2997.38 ppmw to <79.08 ppmw. The microscopic impurity elemental distribution was analyzed using an electron probe microanalyzer (EPMA), and it shows that the impurities were relatively concentrated and gathered in crude selenium. The results enrich the database of selenium evaporation kinetics and lay a foundation for the industrial purification of selenium.

A rapid preparation method of TiO2–xby thermal treatment using H2TiO3as the precursor was proposed compared with the static hydrogenation thermal treatment process. Its adsorption properties of arsenic under visible light were explored and investigated as well. Various colors of TiO2–xwere prepared and characterized via XRD, TEM, BET, and so on. The results indicate that the method of rapid preparation is feasible. The TiO2–xexhibits a larger particle size that varied from 10 nm to 2 μm, and deeper color products were obtained as the treatment temperature increased from 600 to 900 °C. Light yellow TiO2–xwas prepared after increasing the temperature from 600 to 900 °C, Ti4O7and Ti6O11with a dark color were formed under a H2atmosphere at 1500 °C. The arsenic adsorption performances of some samples under visible light were tested, and reveal a high efficiency of TiO2–xin the photocatalytic oxidation arsenic adsorption under visible light, the conversion ratio of As(III) photocatalytic oxidation fluctuates around 2.85 mgAsg–1h–1. In the absence of visible light, the adsorption capacities for As(III) and As(V) are 3.7 and 42.7 mg/g, respectively, at pH = 3. Under visible light condition, the adsorption capacity of As(III) increases sharply to 15.6 mg/g, which provides the foundation for a new application of TiO2–xin the field of arsenic adsorption.

Abstract

Sn–Sb alloy is an ideal candidate for lead-free solder; however, its performance has been inferior to that of Sn–Pb alloy. Here, the authors used ab initio molecular dynamics simulation to investigate the interatomic interaction in Sn–Sb-based lead-free solders. By calculating the electron density distribution, bond population, and partial density of states, the authors found that the Sn–Sb bonds are a mixture of nonlocalized metal and localized covalent bonds. The covalent bond between Sn and Sb is easy to break at higher temperatures, so Sn–Sb (6.4 wt%) had better fluidity than other studied Sn–Sb alloys. Furthermore, adding Cu or Ag into Sn–Sb alloys can decrease the strength of covalent bonds and stabilize the metal bonds, which improves the metallicity and wettability of the Sn–Sb–Cu and Sn–Sb–Cu–Ag systems when the temperature increases. These results are all in good agreement with experimental findings and have significant value for the development of new solder alloys.

CeTiOxand CeZrTiOxcatalysts were prepared by a coprecipitation method and used for selective catalytic reduction of NOxby NH3(NH3-SCR). Various amounts of KNO3were impregnated on the catalyst surface to investigate the effects of Zr addition on the K+-poisoning resistance of the CeTiOxcatalyst. The NH3-SCR performance of the catalysts showed that the NOxremoval activity of the Zr-modified catalyst after poisoning was better than that of the CeTiOxcatalyst. Brunauer-Emmett-Teller data indicated that the Zr-containing catalyst had a larger specific surface area and pore volume both before and after K+poisoning. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy showed that Zr doping inhibited anatase TiO2crystal grain growth, i.e., the molten salt flux effect caused by the loaded KNO3was inhibited. The Ce 3dX-ray photoelectron spectra showed that the Ce3+/Ce4+ratio of CeZrTiOxdecreased more slowly than that of CeTiOxwith increasing K+loading, indicating that Zr addition preserved more crystal defects and oxygen vacancies; this improved the catalytic performance. The acidity was a key factor in the NH3-SCR performance; the temperature-programmed desorption of NH3results showed that Zr doping inhibited the decrease in the surface acidity. The results suggest that Zr improved the K+-poisoning resistance of the CeTiOxcatalyst.

•Magnéli phase Ti4O7was successfully prepared by rapid thermal reduction process.•High-rate performance of cell was greatly improved by a small amount of Ti4O7.•Provides a reference for the development of fast charging of the battery.

Electroporation is a physical process that transiently permeabilizes prokaryotic and eukaryotic cell membranes with an electrical pulse, permitting cell uptake of a variety of biological molecules. Because of the advantages of high efficiency, low toxicity popularity, and controllability, it has been applied in the fields such as cell engineering, genetic engineering, and so on. The principles and characteristics of gene transfection apparatus which is made by us will be illustrated in this paper. The temperature influence is considered and the optical fiber sensor in the apparatus is proposed.