Single crystals of ternary sodium tungsten bronzes have been prepared by the electrolysis of molten Na2W04-W03 system. X-ray powder diffraction and energy dispersive spectroscopy results reveal that the obtained sampl...Single crystals of ternary sodium tungsten bronzes have been prepared by the electrolysis of molten Na2W04-W03 system. X-ray powder diffraction and energy dispersive spectroscopy results reveal that the obtained samples are of cubic phase with empirical formula of Na0.54W03. Electrical resistivity measurement indicates a metallic conducting behavior without any anomaly from 5-300 K.展开更多
Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl3-NaCl melts were studied by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammetry and chronopotentiomet...Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl3-NaCl melts were studied by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammetry and chronopotentiometry analyses showed that Al （Ⅲ） was reduced at 200℃ in two consecutive steps in an electrolyte of molten AlCl3-NaCl system with a composition 52：48 molar ratio. The current-time characteristics of nucleation aluminum on tungsten showed a strong dependence on overpotentials. Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism. The results could lead to a better understanding of the AlCl3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.展开更多
Utilizing the technique of electrolysis with reverse current,sodium tungsten bronze (Na_xWO_3) crystals were prepared from a molten mixture of sodium tungstate (Na_2WO_4 ) and tungstic trioxide (WO_3) at 800℃. Crys...Utilizing the technique of electrolysis with reverse current,sodium tungsten bronze (Na_xWO_3) crystals were prepared from a molten mixture of sodium tungstate (Na_2WO_4 ) and tungstic trioxide (WO_3) at 800℃. Crystal structure, lattice parameter, and s展开更多
The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ra...The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na_(0.854)WO_3 and Na_(0.814)WO_3. Conductivity measurements indicate that Na_xWO_3 show anomalous semiconducting behavior and percolation model was used to interpret it.展开更多
The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system,pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated.The results show that the extracti...The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system,pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated.The results show that the extraction of molybdenum,tungsten and sulfur goes up with the increase of NaOH concentration,oxygen partial pressure and reaction time.The extraction of molybdenum and tungsten also rises up with temperature,but the leaching ratio of sulfur increases initially to a peak of 98% at 150°C and then decreases with the increase of temperature.Under the optimal conditions,the extraction of molybdenum,tungsten and sulfur is more than 95.6%,93.8% and 96.0%,respectively,and the main phases of residue are Bi2O3 and Fe2O3.Therefore,the method of pressure leaching in alkaline solution is provided as an effective separation of molybdenum,tungsten and sulfur from bismuth and a beneficial pretreatment for consequent process.展开更多
二硫化钨由于具有独特的层状结构、大的层间距等优点,已经成为一种非常有潜力的钠离子电池负极材料,但是其导电性差、充放电过程中易发生体积膨胀的不足限制了它进一步的广泛应用.本文以六氯化钨、硫代乙酰胺以及自制的空心碳壳为原料,...二硫化钨由于具有独特的层状结构、大的层间距等优点,已经成为一种非常有潜力的钠离子电池负极材料,但是其导电性差、充放电过程中易发生体积膨胀的不足限制了它进一步的广泛应用.本文以六氯化钨、硫代乙酰胺以及自制的空心碳壳为原料,采用溶剂热法合成了一种中空杆状结构的C/WS_(2)复合材料,将其用于钠离子电池来改善其上述存在的问题.结果表明,在2 A g^(-1)的电流密度下,循环90圈后,C/WS_(2)电极的比容量仍能达到417.1 mAh g^(-1);在10.0 A g^(-1)的大电流密度下,还具有343.3 mAh g^(^(-1))的比容量.因此,中空杆状C/WS2复合材料具有优异的储钠性能.展开更多
A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleach...A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleaching efficiency of more than 96. 92 % can be obtained with a low NaOH consumption by using the mechani-cal activating caustic decomposition , and the content of main impurities (P, As, Si) in Na_2WO_4 solution ob-tained is competitive with that from standard wolframite concentrate by traditional caustic decomposition. Afterrecovering caustic liquor by first crystallization, molylxlenum is removed from Na_2WO_4 solution by ion ex-change method. High-purity sodium tungstate is obtained by second crystallization of Na_2WO_4 solution. Thistechnology has the advantages of good adaptability for raw materials, high removing efficiency of impurities,high tungsten recovery and high economic benefit.展开更多
基金supported by the Natural Science Foundation of Guangdong Province(No.10151063201000003)Fundamental Research Funds for the Central Universities (No.21610706)
文摘Single crystals of ternary sodium tungsten bronzes have been prepared by the electrolysis of molten Na2W04-W03 system. X-ray powder diffraction and energy dispersive spectroscopy results reveal that the obtained samples are of cubic phase with empirical formula of Na0.54W03. Electrical resistivity measurement indicates a metallic conducting behavior without any anomaly from 5-300 K.
基金supported by the National Basic Research Program of China (No.2007CB210305)the National Natural Science Foundation of China (Grant No.50674031).
文摘Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl3-NaCl melts were studied by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammetry and chronopotentiometry analyses showed that Al （Ⅲ） was reduced at 200℃ in two consecutive steps in an electrolyte of molten AlCl3-NaCl system with a composition 52：48 molar ratio. The current-time characteristics of nucleation aluminum on tungsten showed a strong dependence on overpotentials. Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism. The results could lead to a better understanding of the AlCl3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.
文摘Utilizing the technique of electrolysis with reverse current,sodium tungsten bronze (Na_xWO_3) crystals were prepared from a molten mixture of sodium tungstate (Na_2WO_4 ) and tungstic trioxide (WO_3) at 800℃. Crystal structure, lattice parameter, and s
文摘The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na_(0.854)WO_3 and Na_(0.814)WO_3. Conductivity measurements indicate that Na_xWO_3 show anomalous semiconducting behavior and percolation model was used to interpret it.
文摘The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system,pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated.The results show that the extraction of molybdenum,tungsten and sulfur goes up with the increase of NaOH concentration,oxygen partial pressure and reaction time.The extraction of molybdenum and tungsten also rises up with temperature,but the leaching ratio of sulfur increases initially to a peak of 98% at 150°C and then decreases with the increase of temperature.Under the optimal conditions,the extraction of molybdenum,tungsten and sulfur is more than 95.6%,93.8% and 96.0%,respectively,and the main phases of residue are Bi2O3 and Fe2O3.Therefore,the method of pressure leaching in alkaline solution is provided as an effective separation of molybdenum,tungsten and sulfur from bismuth and a beneficial pretreatment for consequent process.
文摘二硫化钨由于具有独特的层状结构、大的层间距等优点,已经成为一种非常有潜力的钠离子电池负极材料,但是其导电性差、充放电过程中易发生体积膨胀的不足限制了它进一步的广泛应用.本文以六氯化钨、硫代乙酰胺以及自制的空心碳壳为原料,采用溶剂热法合成了一种中空杆状结构的C/WS_(2)复合材料,将其用于钠离子电池来改善其上述存在的问题.结果表明,在2 A g^(-1)的电流密度下,循环90圈后,C/WS_(2)电极的比容量仍能达到417.1 mAh g^(-1);在10.0 A g^(-1)的大电流密度下,还具有343.3 mAh g^(^(-1))的比容量.因此,中空杆状C/WS2复合材料具有优异的储钠性能.
文摘A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleaching efficiency of more than 96. 92 % can be obtained with a low NaOH consumption by using the mechani-cal activating caustic decomposition , and the content of main impurities (P, As, Si) in Na_2WO_4 solution ob-tained is competitive with that from standard wolframite concentrate by traditional caustic decomposition. Afterrecovering caustic liquor by first crystallization, molylxlenum is removed from Na_2WO_4 solution by ion ex-change method. High-purity sodium tungstate is obtained by second crystallization of Na_2WO_4 solution. Thistechnology has the advantages of good adaptability for raw materials, high removing efficiency of impurities,high tungsten recovery and high economic benefit.
