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Preparation of titanium powders by calciothermic reduction of titanium dioxide 被引量:7
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作者 万贺利 徐宝强 +3 位作者 戴永年 杨斌 刘大春 森维 《Journal of Central South University》 SCIE EI CAS 2012年第9期2434-2439,共6页
To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide (w(TiO2)〉98%), based on the preform reduction process (PRP), was investigated by me... To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide (w(TiO2)〉98%), based on the preform reduction process (PRP), was investigated by means of XRD, SEM and EDS. In this process, the mixture of TiO2 powder and CaC12 was pressed into pieces as feed preform and was reduced by calcium vapor. Titanium powders was recovered after leaching from the reduced preform with hydrochloric acid and deionized water. The results indicate when the mass ratio of CaC12 to TiO2 is about 1:4 and at a constant temperature of 1 273 K for 6 h in vacuum furnace, titanium powders with 99.55% purity by EDS analysis and irregular shape (8-15 μm in particle size) are obtained. 展开更多
关键词 titanium powders titanium dioxide calciothermic reduction calcium chloride
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Effects of temperature variation on Li_xFe PO_4/C(0
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作者 肖政伟 张英杰 胡国荣 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第6期2043-2051,共9页
Li Fe PO4/C was prepared via solid state reaction and characterized with X-ray powder diffraction and charge–discharge test. As-prepared Li Fe PO4/C has a triphylite structure and exhibits an excellent rate capabilit... Li Fe PO4/C was prepared via solid state reaction and characterized with X-ray powder diffraction and charge–discharge test. As-prepared Li Fe PO4/C has a triphylite structure and exhibits an excellent rate capability and capacity retention. Electrochemical impedance spectroscopy(EIS) was applied to investigate LixFe PO4/C(0<x<1) electrode on temperature variation. The valid equivalent circuit for EIS fitting was determined which contains an intercalation capacitance for Li+ ion accumulation and consumption in the electrode reaction. The surface layer impedance needs to be included in the equivalent circuit when Li Fe PO4/C is deeply delithiated at a relatively high temperature. EIS examination indicates that a temperature rise leads to a better reversibility, lower charge transfer resistance, higher exchange current density J0 and greater Li+ ion diffusion coefficient for the LixFe PO4/C electrode process. The Li+ ion concentration in LixFe PO4/C is potential to impact the Li+ ion diffusion coefficient, and a decrease in the former results in an increase in the latter. 展开更多
关键词 lithium ion cell LIFEPO4/C el :ctrode process electrochemical impedance spectroscopy equivalent circuit Li+ ion diffusion coefficient
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间硝基苯甲酸/8-羟基喹啉(1/1)共晶体结构解析与Rietveld精修
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作者 居威材 陶亚秋 +1 位作者 沈晓冬 潘志刚 《南京工业大学学报(自然科学版)》 北大核心 2017年第3期126-131,共6页
通过溶液冷却结晶法制备出间硝基苯甲酸/8-羟基喹啉(1/1)共晶体。利用粉末X线衍射技术及傅里叶红外光谱技术采集该共晶体的粉末衍射数据及红外光谱数据。对该共晶体粉末衍射数据进行指标化及晶体结构解析,并参照红外分析结果对该共晶体... 通过溶液冷却结晶法制备出间硝基苯甲酸/8-羟基喹啉(1/1)共晶体。利用粉末X线衍射技术及傅里叶红外光谱技术采集该共晶体的粉末衍射数据及红外光谱数据。对该共晶体粉末衍射数据进行指标化及晶体结构解析,并参照红外分析结果对该共晶体的晶体结构进行了Rietveld精修,最终测定了间硝基苯甲酸/8-羟基喹啉(1/1)共晶体的晶体结构。该共晶体的一个不对称单元中包含一个间硝基苯甲酸分子(去质子化的)和一个8-羟基喹啉分子(质子化的)。8-羟基喹啉上的酚羟基和芳香N原子与间硝基苯甲酸上的羧基通过O—H…O氢键、N—H…O氢键形成二聚体,沿b轴方向相互平行的二聚体之间存在着π…π堆砌作用。 展开更多
关键词 共晶体 粉末x线衍射 RIETVELD精修 质子转移 氢键
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Facile synthesis of Zn_2GeO_4 nanorods toward improved photocatalytic reduction of CO_2 into renewable hydrocarbon fuel 被引量:4
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作者 杨明 金效齐 《Journal of Central South University》 SCIE EI CAS 2014年第7期2837-2842,共6页
Zn2GeO4 nanorods were prepared by a surfactant-assisted solution phase route.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission ... Zn2GeO4 nanorods were prepared by a surfactant-assisted solution phase route.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),UV-vis diffuse reflection spectroscopy and photoluminescence(PL) spectroscopy.The possible formation mechanism of Zn2GeO4 nanorods was discussed.It was supposed that the CTA+ cations preferentially adsorb on the planes of Zn2GeO4 nanorods,leading to preferential growth along the c-axis to form the Zn2GeO4 rods with larger aspect ratio and higher surface area,which showed the improved photocatalytic activity for photoreduction of CO2.The photoluminescence(PL) property of Zn2GeO4 nanorods was investigated through the emission spectra. 展开更多
关键词 PHOTOCATALYSIS Zn2GeO4 nanorod cetyl trimethyl ammonium bromide(CTAB)
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Characterization of ultrafine copper powder prepared by novel electrodeposition method 被引量:3
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作者 贺玮 段学臣 朱磊 《Journal of Central South University》 SCIE EI CAS 2009年第5期708-712,共5页
The auto-evolved ultrafine copper powders were synlhesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray ... The auto-evolved ultrafine copper powders were synlhesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray powder diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and laser size distribution analyzer (SL) respectively. The formation mechanisms of the powders and the efficiency of the elctrodeposition were discussed. The results show that the as-prepared powders are high-purity copper nanoparticles with the fcc structure taking a mixture of fishbone-like and irregular shapes When the concentration of Cu^2+ increases from 0.03 to 0.09 mol/L, the average size of copper particles increases from 0.92 to 1.80 μm, and current efficiency of electrodeposition linearly changes from 66.5% to 91.3%. 展开更多
关键词 copper powder: electrodepositon uhrasound
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Preparation of microsized single-crystalline Co_3O_4 by high-temperature hydrolysis
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作者 李启厚 刘智勇 +1 位作者 刘志宏 胡雷 《Journal of Central South University》 SCIE EI CAS 2011年第4期993-997,共5页
Microsized single-crystalline Co3O4 has been synthesized by high-temperature hydrolysis of CoCD2H20 at 600℃. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) an... Microsized single-crystalline Co3O4 has been synthesized by high-temperature hydrolysis of CoCD2H20 at 600℃. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that the as-prepared powders are microsized single-crystalline CO3O4 with cubic spinel structure. An increase in the high-temperature hydrolysis time results in the evolution of particle shapes from cube to quasi-sphere, and then to octahedron. The effect of NaCl additive on the surface morphologies of Co3O4 particles was experimentally investigated. The results indicate that the NaCl additive acts as an inert disperse phase in the high-temperature hydrolysis, and prevents the aggregation of Co3O4 particles effectively. 展开更多
关键词 CO3O4 crystal structure HYDROLYSIS surface morphology
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Dissolution mechanism and solubility of hemimorphite in NH_3-(NH_4)_2SO_4-H_2O system at 298.15 K
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作者 李琴香 陈启元 胡慧萍 《Journal of Central South University》 SCIE EI CAS 2014年第3期884-890,共7页
The dissolution mechanism of hemimorphite in NH3-(NH4)2SO4-H2O system at 298.15 K was investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy ... The dissolution mechanism of hemimorphite in NH3-(NH4)2SO4-H2O system at 298.15 K was investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. The results show that hemimorphite is soluble in NH3-(NH4)2SO4-H2O system and its residue exists in the form of an amorphous SiO2 layer on the hemimorphite surface. The XPS data also indicate that the Si 2p3/2 and O ls spectra of the hemimorphite are broadened and shift to higher binding energies and their binding energies are closer to silica with an increase of total ammonia and time. Solubility of hemimorphite in NH3-(NH4)2SO4-H2O system was measured by means of isothermal solution method at 298.15 K based on the study of the dissolution mechanism of hemimorphite. The results show that the solubility of zinc in solution increases firstly and then decreases with the increase of cr(NH3) (total ammonia concentration) at different NH3/NH4^+ ratios. The solubility of silicon in solution decreases from 0.0334 mol/kg in ct(NH3)-4.1245 mol/kg NH3-(NH4)2SO4-H2O solution to 0.0046 mol/kg in cT(NH3)=7.6035 mol/kg NH3-(NH4)2SO4-H2O solution. 展开更多
关键词 HEMIMORPHITE ammoniacal solution dissolution mechanism SOLUBILITY
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