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金刚石微粉表面的纳米硅烷化改性及其抗氧化性能 被引量:3
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作者 庞爱红 董欣然 +6 位作者 董俊言 沈方韧 谭素玲 贾晨超 董书山 毛青青 吴增凤 《金刚石与磨料磨具工程》 CAS 北大核心 2022年第4期410-420,共11页
采用溶胶−凝胶技术和正硅酸乙酯(TEOS)的水解−缩合反应,在金刚石微粉表面包覆一层厚度为2~10 nm的富含活性氧基团的纳米氧化硅非晶凝胶膜,凝胶膜在加热至一定温度后,其二氧化硅可由非晶相向晶体相转变。金刚石微粉在空气中的初始氧化温... 采用溶胶−凝胶技术和正硅酸乙酯(TEOS)的水解−缩合反应,在金刚石微粉表面包覆一层厚度为2~10 nm的富含活性氧基团的纳米氧化硅非晶凝胶膜,凝胶膜在加热至一定温度后,其二氧化硅可由非晶相向晶体相转变。金刚石微粉在空气中的初始氧化温度从原料金刚石的500℃提升到其TEOS覆膜改性后的550℃。在TEOS覆膜中添加纳米硅粉改性后,金刚石微粉样品在空气中的初始氧化温度可进一步提升至610℃;且经过800℃的热处理后,样品剩余量比之原料金刚石量大幅度提升,表明TEOS覆膜中添加纳米硅粉后可进一步提升金刚石微粉的高温抗氧化性能。TEOS覆膜中富含的活性氧基团能与树脂/陶瓷结合剂间产生化学反应,有利于提高结合剂对金刚石的把持力,可为制备高性能的树脂/陶瓷结合剂金刚石工具提供良好的功能化改性原材料。 展开更多
关键词 金刚石表面改性 正硅酸乙酯(TEOS) 非晶二氧化硅膜 溶胶−凝胶法 差热分析
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Influence of dopant content on morphology and optical constants of ZnO:Na films by sol-gel method 被引量:4
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作者 吕建国 曹春斌 +1 位作者 宋学萍 孙兆奇 《Journal of Central South University》 SCIE EI CAS 2011年第1期42-47,共6页
Undoped and Na-doped ZnO films were deposited by sol-gel method.The effects of sodium incorporation on structure,surface morphology and optical constants of the films were investigated.X-ray diffraction patterns show ... Undoped and Na-doped ZnO films were deposited by sol-gel method.The effects of sodium incorporation on structure,surface morphology and optical constants of the films were investigated.X-ray diffraction patterns show the hexagonal wurtzite polycrystalline structure and that the sodium incorporation leads to the change in the structural characteristics of ZnO films.The SEM observations show that the surface morphology of the films is affected by the sodium incorporation.The transmission spectra show that the average transmittance of the films is above 85% in the visible range.The absorption edge initially blue-shifts and then red-shifts with the increase of Na doping content.The optical constants of these films were calculated using transmission spectra.Refractive indices of the films in the visible range decrease at first and then increase with increasing Na doping content. 展开更多
关键词 Na-doped ZnO sol-gel method transmission spectra optical constants
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Preparation and properties of PEO/LiClO_4/KH560-SiO_2 composite polymer electrolyte by sol-gel composite-in-situ method 被引量:4
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作者 潘春跃 高金环 +2 位作者 张倩 冯庆 巢猛 《Journal of Central South University of Technology》 2008年第3期295-300,共6页
Composite polymer electrolytes based on polyethylene oxide(PEO) were prepared by using LiClO4 as doping salt and silane-modified SiO2 as filler. SiO2 was formed in-situ in (PEO)8LiClO4 matrix by the hydrolysis and con... Composite polymer electrolytes based on polyethylene oxide(PEO) were prepared by using LiClO4 as doping salt and silane-modified SiO2 as filler. SiO2 was formed in-situ in (PEO)8LiClO4 matrix by the hydrolysis and condensation reaction of Si(OC4H9)4. The crystallinity,morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry,scanning electron microscopy,atom force microscopy and alternating current impedance spectroscopy,respectively. Compared with the crystallinity of the unmodified SiO2 as inert filler,that of composite polymer electrolytes is decreased. The results show that silane-modified SiO2 particles are uniformly dispersed in (PEO)8LiClO4 composite polymer electrolyte film and the addition of silane-modified SiO2 increases the ionic conductivity of the (PEO)8LiClO4 more noticeably. When the mass fraction of SiO2 is about 10%,the conductivity of (PEO)8LiClO4-modified SiO2 attains a maximum value of 4.8×10-5 S·cm-1. 展开更多
关键词 polyethylene oxide(PEO) SOL-GEL composite-in-situ polymer electrolyte ionic conductivity
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Selective catalytic reduction of NO with NH_3 over sol-gel-derived CuO-CeO_2-MnO_x/γ-Al_2O_3 catalysts 被引量:2
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作者 赵清森 向军 +3 位作者 孙路石 石金明 苏胜 胡松 《Journal of Central South University》 SCIE EI CAS 2009年第3期513-519,共7页
Granular CuO-CeO2-MnOx/γ-Al2O3 catalysts were synthesized by the sol-gel method. The performance of the CuO-CeO2-MnOx/γ-Al2O3 catalysts for the selective catalytic reduction (SCR) was studied in a fixed bed system. ... Granular CuO-CeO2-MnOx/γ-Al2O3 catalysts were synthesized by the sol-gel method. The performance of the CuO-CeO2-MnOx/γ-Al2O3 catalysts for the selective catalytic reduction (SCR) was studied in a fixed bed system. Preliminary tests were carried out to analyze the behavior of NH3 and NO over catalyst in the presence of oxygen. The optimum temperature range for SCR over the CuO-CeO2-MnOx/γ-Al2O3 catalysts is 300-400 ℃ . The catalysts maintain nearly 100% NO conversion at 350 ℃. The NH3 oxidation experiments show that both NO and N2O are produced gradually with the increase of temperature. The catalysts in this experiment have a stronger oxidation property on NH3, which improves the denitrification activity at low temperature. The over-oxidation of NH3 at high temperature is the main cause leading to a decrease in the NO conversion. The NH3 and NO desorption experiments show that NH3 and NO can be adsorbed on CuO-CeO2-MnOx/γ-Al2O3 granular catalysts. The transient response of NH3 and NO indicates that the SCR reaction proceeds in accordance with the Eley-Rideal mechanism. The adsorbed NO has little influence on the denitrification activity in SCR process. 展开更多
关键词 sol-gel method CuO-CeO2-MnOx/γ-Al2O3 NH3 NO CONVERSION selective catalytic reduction (SCR)
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Photocatalytic H_2 evolution activity of CuO/ZrO_2 composite catalyst under simulated sunlight irradiation 被引量:2
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作者 阎建辉 姚茂海 +2 位作者 张丽 唐有根 杨海华 《Journal of Central South University》 SCIE EI CAS 2011年第1期56-62,共7页
Zirconia-supported CuO (CuO/ZrO2) composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO2 materials were also prepared by solid state reaction and ... Zirconia-supported CuO (CuO/ZrO2) composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO2 materials were also prepared by solid state reaction and co-precipitation method. The as-prepared powders were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), and thermogravimetric-differential thermal analysis (TG-DTA). The photocatalytic activity of CuO/ZrO2 catalyst was investigated based on the H2 evolution from oxalic acid solution under simulated sunlight irradiation. The effects of molar ratio of CuO to ZrO2, preparation method, phase change with the calcination temperature and the durability on the photocatalytic activity of the photocatalyst were investigated in detail. It is found that the optimal activity of photocatalytic H2 evolution (2.41 mmol.h i.g-~) can be obtained when CuO/ZrO2 composite photocatalyst is synthesized by sol-gel technique and the mole ratio of CuO to ZrO2 is 40%. The activity of copper oxide supported on monoclinic ZrO2 calcined at higher temperature is much higher than that on tetragonal ZrO2 calcined at lower temperature, and the best calcination temperature is 900 ℃. 展开更多
关键词 CuO/ZrO2 photocatalytic activity hydrogen evolution simulated sunlight
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Photo oxidation of DBT using carbon nanotube titania composite as visible light active photo catalyst 被引量:1
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作者 BARMALA Molood BEHNOOD Mohammad OMIDKHAH Mohammad Reza 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第7期1642-1650,共9页
Sulfur removal from liquid fuels has increased in importance in recent years. Although hydrodesulfurization is the usual method for removing sulfur, the elimination of thiophene compounds using this process is difficu... Sulfur removal from liquid fuels has increased in importance in recent years. Although hydrodesulfurization is the usual method for removing sulfur, the elimination of thiophene compounds using this process is difficult. Photocatalysis is an alternative method being developed for thiophene removal at ambient conditions. Among semiconductors, titania has shown good potential as a photo-catalyst; however, quick recombination of electron holes hinders its commercial use. One way to decrease the recombination rate is to combine carbon nanotubes with a semiconductor. In this work, multiwall carbon nanotube (MWCNT) / titania composites were prepared with different mass ratios of MWCNT to titania using tetraethyl orthotitanate (TEOT) and titanium tetra isopropoxide (TTIP) as precursors of titania. Dibenzothiophene (DBT) photocatalytic removal from n-hexane was measured in both the presence and absence of oxygen. The results indicated that the best removal occurred when the MWCNT to titania ratio was 1. When the ratio exceeded this number, DBT removal efficiency decreased due to light scattering. Also, the composites prepared by TEOT exhibited better efficiency in DBT removal. The research findings suggested that the obtained composite was a visible light active photocatalyst and exhibited better performance in the presence of oxygen. Kinetics of photocatalytic DBT removal was a first-order reaction with removal rate constant 0.7 h–1 obtained at optimum conditions. 展开更多
关键词 advanced oxidation processes carbon nanotube PHOTOCATALYSIS UV kinetics SEMICONDUCTOR sol-gel process
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Increased photo-catalytic removal of sulfur using titania/MWCNT composite 被引量:1
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作者 Molood Barmala Abdolsamad Zarringhalam Moghadam Mohammad Reza Omidkhah 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第5期1066-1070,共5页
Titania coating of multi wall carbon nano tube(MWCNT) was carried out by sol-gel method in order to improve its photo catalytic properties.The effect of MWCNT/TiO_2 mass to volume ratio on adsorption ability,reaction ... Titania coating of multi wall carbon nano tube(MWCNT) was carried out by sol-gel method in order to improve its photo catalytic properties.The effect of MWCNT/TiO_2 mass to volume ratio on adsorption ability,reaction rate and photo-catalytic removal efficiency of dibenzothiophene(DBT) from n-hexane solution was investigated using a 9 W UV lamp.The results show that the addition of nanotubes improves the photo-catalytic properties of TiO_2 by two factors;however,the DBT removal rate versus MWCNT content is found to follow a bimodal pattern.Two factors are observed to affect the removal rate of DBT and produce two optimum values for MWCNT content.First,large quantities of MWCNTs prevent light absorption by the solution and decrease removal efficiency.By contrast,a low dosage of MWCNT causes recombination of the electron holes,which also decreases the DBT removal rate.The optimum MWCNT contents in the composite are found to be 0.25 g and 0.75 g MWCNT per 80 m L of sol. 展开更多
关键词 photo oxidation DESULFURIZATION SOL-GEL TITANIA multi wall carbon nano tube (MWCNT)
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Microstructure and electrical properties of La_2 O_3-doped ZnO-based varistor thin films by sol-gel process 被引量:1
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作者 徐东 姜斌 +4 位作者 崔凤单 杨永涛 徐红星 宋琪 于仁红 《Journal of Central South University》 SCIE EI CAS 2014年第1期9-13,共5页
Microstructure and electrical properties of La2 O3-doped ZnO-Bi2 O3 thin films prepared by sol–gel process have been investigated.X-ray diffraction shows that most diffraction peaks of ZnO are equal,and the crystals ... Microstructure and electrical properties of La2 O3-doped ZnO-Bi2 O3 thin films prepared by sol–gel process have been investigated.X-ray diffraction shows that most diffraction peaks of ZnO are equal,and the crystals of ZnO grow well.Scanning electron microscopy and atomic force microscopy results indicate that the samples have a good structure and lower surface roughness.The nonlinear V–I characteristics of the films show that La2 O3 develops the electrical properties largely and the best doped content is 0.3% lanthanum ion,with the leakage current of 0.25 mA,the threshold field of 150 V/mm and the nonlinear coefficient of 4.0 in detail. 展开更多
关键词 zinc oxide VARISTOR FILM sol-gel process electrical properties MICROSTRUCTURE
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Synthesis of CaCu_3Ti_4O_(12)powders and ceramics by sol-gel method using decanedioic acid and its dielectric properties 被引量:2
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作者 王茂华 周芙 +1 位作者 王秋丽 姚超 《Journal of Central South University》 SCIE EI CAS 2012年第12期3385-3389,共5页
The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid (decanoic acid and decanedioic acid). The xerogels, powders and ceramics were characterized by ... The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid (decanoic acid and decanedioic acid). The xerogels, powders and ceramics were characterized by the methods of TG-DTG, FT-IR, XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The results indicated that the powders calcined at 850 ℃ for 2 h are both nanometer scale particles. After sintering, the ceramics mainly consist of the CaCu3Ti4O12 phase. Compared with the powders prepared using monoacid, the particle size of the powders prepared using diacid obviously increases, and the grain size, the relative density and the whole permittivity of the ceramics increase as well. Specially, the ceramic prepared using decanedioic acid has higher relative density (97.3%), dielectric constant (316 808) and lower dielectric loss (0.242 5) at 30 ℃ (10 kIaz) 展开更多
关键词 CACU3TI4O12 sol-gel method decanedioic acid PERMITTIVITY
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Electrochemical performance of LiFePO_4/(C+Fe_2P) composite cathode material synthesized by sol-gel method 被引量:2
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作者 陈权启 李小栓 王建明 《Journal of Central South University》 SCIE EI CAS 2011年第4期978-984,共7页
A LiFePO4/(C+Fe2P) composite cathode material was prepared by a sol-gel method using Fe(NO3)3.9H20, LiAc·H2O), NHaH2PO4 and citric acid as raw materials, and the physical properties and electrochemical perf... A LiFePO4/(C+Fe2P) composite cathode material was prepared by a sol-gel method using Fe(NO3)3.9H20, LiAc·H2O), NHaH2PO4 and citric acid as raw materials, and the physical properties and electrochemical performance of the composite cathode material were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical tests. The Fe2P content, morphology and electrochemical performance of LiFePOa/(C+Fe2P) composite depend on the calcination temperature. The optimized LiFePO4/(C+FeeP) composite is prepared at 650 ~C and the optimized composite exhibits sphere-like morphology with porous structure and Fe2P content of about 3.2% (mass fraction). The discharge capacity of the optimized LiFePO4/(C+FeRP) at 0.1C is 156 and 161 mA.h/g at 25 and 55 ℃, respectively, and the corresponding capacity retentions are 96% after 30 cycles; while the capacity at 1C is 142 and 149 mA.h/g at 25 and 55 ℃, respectively, and the capacity still remains 135 and 142 mA-h/g after 30 cycles at 25 and 55℃, respectively. 展开更多
关键词 LiFePO4/(C+Fe2P) composite sol-gel sphere-like morphology electrochemical performance
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Preparation and properties of SrBi_(2.2) Ta_2O_9 thin film
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作者 王文 贾德昌 周玉 《Journal of Central South University of Technology》 EI 2005年第4期376-379,共4页
SrBi2.2 Ta2O9(SBT) thin film with thickness of 2μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr(CH3COO)2·1/2H2O] and bismth subnitrate [BiO(NO3)], and tantalum ethox... SrBi2.2 Ta2O9(SBT) thin film with thickness of 2μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr(CH3COO)2·1/2H2O] and bismth subnitrate [BiO(NO3)], and tantalum ethoxide [Ta(OCH2CH3)5] as source materials, glacial acetic and ethylene glycol as solvents. The X-ray diffraction(XRD) and transmission electron microscope(TEM) results indicate that SBT layer-perovskite phase obtained has to be single phase, SBT thin film is formed after being annealed at 800℃ for 1min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO2/Si is obtained, and the measured polarization value of the SBT thin film is 4.2μC/cm2. 展开更多
关键词 SrBi2.2 Ta2O9 sol-gel technique thin film FERROELECTRIC
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Preparation and electrochemical performance of Li_2Mn_(0.5)Fe_(0.5)SiO_4 cathode material with sol-gel method for lithium ion batteries
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作者 胡传跃 郭军 +1 位作者 文瑾 彭秧锡 《Journal of Central South University》 SCIE EI CAS 2014年第4期1285-1289,共5页
Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5... Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g. 展开更多
关键词 lithium ion battery Li2Fe0.5Mn0.5SiO4 citric acid assisted sol-gel method cathode
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