共查询到18条相似文献,搜索用时 203 毫秒
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用直流碳弧法在阳极石墨棒中加入α-Fe2O3产生碳包Fe纳米晶,研究在复合石墨棒中加入不同的Fe2O3含量对碳包Fe纳米晶的形貌、结构特性及晶粒尺寸分布的影响,探讨碳包Fe纳米晶的形成原因及碳弧法中氦气压力和Fe2O3含量对复合石墨棒所产生的碳灰的C60/70产率的影响.结果表明:Fe2O3复合石墨棒所产生的碳灰含有α-Fe相、Fe3C相和石墨相,没有氧化物相.复合阳极棒中的Fe2O3含量决定了碳包Fe纳米晶的数量和晶粒直径分布,碳弧法中的He气压力仍是影响掺Fe2O3阳极棒所产生的碳灰的C60/70产率的主要因素,但对碳包Fe纳米晶的产率影响不大.掺Fe2O3阳极棒所产碳灰的C60/70产率与氦气压力的关系和纯石墨阳极棒的这一关系比较,存在着显著的差别. 相似文献
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使用梯度过渡层的掺Cr碳膜的显微组织特征 总被引:1,自引:0,他引:1
为了探究C、Cr两种主要成膜元素在非晶碳膜中的存在和分布状态,采用非平衡磁控溅射离子镀技术制备出了具有梯度过渡层的掺Cr碳膜,利用高分辨透射电子显微术(HRTEM)分析了薄膜的显微组织.结果表明,沉积在硅晶片上的纯Cr底层具有典型的柱状晶结构,其上的梯度过渡层则由各种形态的Cr纳米晶和富碳非晶基质构成.沿薄膜生长方向,随着Cr含量逐渐降低,过渡层中的Cr纳米晶依次形成层片晶、岛状晶和微晶.掺Cr碳膜的工作层则是一种非晶的纳米多层膜.膜中的C始终以非晶态存在,所观察到的结晶相均属金属Cr,同时纯Cr层柱状晶和过渡层中的各种Cr纳米晶都不同程度地具有(110)晶面的择优取向. 相似文献
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以葡萄糖为原料水热合成碳球作为模板剂,将其与TiO2纳米晶共混制备纳米多孔TiO2光阳极。采用场发射电子扫描电镜(SEM)、台阶仪、紫外-可见分光光度计(UV-Vis)等对TiO2薄膜的表面形貌、厚度和散射能力进行表征。研究发现,随着碳球含量的增加,光阳极单位体积内的表面积先增加后减小;薄膜对光的散射能力也呈现同样趋势。采用所制备的光阳极组装染料敏化太阳能电池,性能测试结果表明,随着碳球含量的增加,电池短路电流密度先增加,后减小。当碳球加入量为TiO2纳米晶质量的3%时,电池光电转换效率达到最佳为5.15%。 相似文献
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通过介绍在气体和液体介质中激光与固体材料相互作用的过程,评述了激光在不同介质中发生物理化学现象的差异.与气相中相比,激光冲蚀液体中固体材料产生的气态等离子区受到了液体限制,在该区域会产生更高的气态密度、温度和压力,适合于亚稳相纳米晶的合成.同时评述了激光制备碳基纳米材料的进展.激光在气相和液相中均可制得碳纳米管,气相中适于制备结构完整的碳纳米管,而液相中有利于纳米金刚石的合成.激光冲蚀液体中的石墨靶制备的纳米金刚石粒径较大,辐照石墨悬浮液工艺不仅可以获得超细的纳米金刚石还可以获得线型碳.激光法制备的碳基纳米材料具有尺寸小、纯度高和形状多样性,在未来有着广泛的潜在应用价值. 相似文献
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本文用真空电弧熔炼法首次制备了Ce2Co17-xAlx化合物,利用X-射线和磁测量手段,研究了化合物的结构与内禀磁性。重点讨论了Al原子在Co次晶格四个不同晶位择优占位与Co次晶格磁晶各向异性的关系,其中18h晶位对Co次晶格各向异性负贡献起重要作用。 相似文献
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《Materials Chemistry and Physics》1998,55(2):167-170
Using an Fe2O3-containing composite anode instead of an Fe-containing composite anode in the Kratschmer-Huffman carbon arc method, carbon-coated Fe (not Fe2O3) nanocrystals are produced both in the soot on the reactor walls and in the cathode deposits. The encapsulates also contain a little iron carbide, but do not contain iron oxides, as identified by transmission electron microscopy ( TEM ) and X-ray diffraction (XRD). As compared with Ni2O3- and Co2O3-containing composite anodes, the action of the Fe2O3-containing composite anode is unique. When the Fe2O3 contents in the composite graphite rod for the carbon arc nanocrystal production are increased in the range 5-33 wt.%, the effect on the structure and diameter distribution of the iron nanocrystals is investigated. The diameter distribution of iron nanocrystals is about 1–30 nm. The effect of helium pressure in the range 80–680 torr on the yield of C60/70 in carbon soot produced from the composite graphite rod has also been examined. We present a novel result about the relationship of C60/70 yields and helium gas pressure using a composite anode differing remarkably from the result using a homogeneous graphite anode in arc discharge. 相似文献
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首次将四氧化三钴/石墨(Co_3O_4/G)复合材料用于海底沉积物微生物燃料电池(MSMFCs)阳极改性,并对阳极电化学性能和电池性能进行研究。结果表明,Co3O4/G复合改性阳极表面的微生物附着数量是空白组的6.1倍;其氧化还原电化学活性和电容特性分别是空白组的16.2倍和31.0倍;交换电流密度达到1.366×10-3m A·cm-2,电子转移动力学活性是空白组的215.6倍,且其抗极化能力最强;电荷转移电阻降至空白组的2/5,并且双电层电容和生物膜电容均得到增加;其组成电池的功率密度为735.1 m W/m2,是空白组电池的4.6倍。机理分析表明,Co_3O_4和石墨的协同作用使复合改性阳极的电容性能和电子转移速率得到提高。 相似文献
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采用热裂解方法, 热解分散于聚偏二氟乙烯溶液中的硅和石墨, 得到了具有稳定电化学循环性能的Si/C/石墨复合负极材料。透射电子显微镜观察发现, 复合材料形貌为无定型碳包裹硅颗粒的核壳结构。通过系统研究不同Si粒径和石墨含量对电极电化学性能的影响, 发现Si颗粒粒径越小复合材料电化学循环稳定性能越优越, 适当的降低石墨含量有利于电极材料剩余比容量的提高。当Si粒径为50 nm, Si与石墨质量比1:1时, 电极材料具有1741.6 mAh/g的首次放电比容量和72.5%的首次库仑效率, 60次循环后, 可逆比容量保持在820 mAh/g。热解有机物形成碳包覆的结构能有效地改善硅基类负极材料的电化学循环性能。 相似文献
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A new method to produce large quantities of single-walled carbon nanotubes (SWCNTs) with high purity is developed. Using several
composite graphite rods containing Y and Ni powder as the anode, and a high purity graphite hemisphere as the cathode, a cloth-like
deposit could be obtained by dc arc-discharge in helium at high temperature. The deposit contained about 50% SWCNTs. In this
way, more than one gram deposit could be produced in a few minutes. The structure and morphology of the SWCNTs were then examined
using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis.
The article is published in the original. 相似文献
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借助机械球磨法, 成功地利用层状硫化物MoS2对膨胀石墨实现了有效剥离, 得到石墨烯与MoS2的复合材料。球磨处理后, 元素C均匀地分散在复合材料中。MoS2 与膨胀石墨的质量比越高, 得到的复合材料中具有石墨烯特征的石墨就越多, 但相应的石墨烯的缺陷也越多。优化后的复合材料用作锂离子电池负极材料时显示出良好的电池性能, 在小倍率0.1 Ah/g电流密度下充放电循环70次后, 电池容量仍保持在~ 570 mAh/g; 在大倍率1 A/g电流密度下充放电循环55次后, 电池容量仍能保持在~ 450 mAh/g。 相似文献
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以碳纳米管和氧化石墨烯为原料,二者按5∶3混合超声分散再高温还原制备碳纳米管/石墨烯/天然石墨(CNTs/rGO/NG)锂离子复合负极材料。采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(FTIR)和电化学测试等分析技术对复合材料的形貌、结构、电化学进行表征。结果表明:石墨烯和碳纳米管在天然石墨表面形成三维立体网络结构。与纯天然石墨相比,CNTs/rGO/NG复合材料具有良好的倍率性能和循环寿命,在0.1C时首次放电比容量为479mAh/g,可逆容量达473mAh/g,循环100次后容量为439.5mAh/g,容量保持率为92%,在0.5,1,5C不同电流倍率时容量依次为457,433,394mAh/g。 相似文献
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Paladugu MC Maneesh K Nair PK Haridoss P 《Journal of nanoscience and nanotechnology》2005,5(5):747-752
In this work Carbon nanotubes have been synthesized by arc discharge in open air. A TIG welding ac/dc inverter was used as the power source for arc discharge. During each run of the arc discharge based synthesis, the anode was a low purity (approximately 85% C by weight) graphite rod. The effect of varying the atmosphere on the yield of soot of the carbon nanotube containing carbon soot has been studied. Various soots were produced, purified by oxidation and characterized to confirm formation of carbon nanotubes and their relative quality, using transmission electron microscopy, Raman spectroscopy, and XRD. It was found that the yield of soot formed on the cathode is higher when synthesis is carried out in open air than when carried out in a flowing argon atmosphere. When synthesized in open air, using a 7.2-mm-diameter graphite rod as anode, the yield of soot was around 50% by weight of the graphite consumed. Current and voltage for arcing were at identical starting values in all the experiments. This modified method does not require a controlled atmosphere as in the case of a conventional arc discharge method of synthesis and hence the cost of production may be reduced. 相似文献
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Tao Yu Jin-Chai Li Feng-Xin Cai Xiang-Jun Fan Ming-Sheng Ye Rong Chen Wan Wu Nian Xiao De-Cheng Tian Wen-Kuan Zhao You-Ling Fang Ai-Yan Kuang 《Fullerenes, Nanotubes and Carbon Nanostructures》1994,2(3):223-231
A new homemade are fullerene generator used in this experiment is reported. The comparation of yields of fullerenes (C60/C70 mixture) was studied by different power supplies (AC and DC), different gaps of two graphite rods and different He pressure between 0.4×104- 2.8×104 Pa. In our experiment, the highest yield up to 13% was achieved, when DC discharge was used and the optimum He pressure was near 0.8×104 - 1.6×104 Pa.
The mixed fullerene was analyzed by electron impact masa spectnun (EIMS). The relative amount af C60 to C70 was 4.2 to 1. After column chromatography aeperation with hexane on alumina, 99.9% Cso was obtained. FTIR and 1aC-NMR epectrum were ueed to characterize the pure C60 samples. 相似文献
The mixed fullerene was analyzed by electron impact masa spectnun (EIMS). The relative amount af C60 to C70 was 4.2 to 1. After column chromatography aeperation with hexane on alumina, 99.9% Cso was obtained. FTIR and 1aC-NMR epectrum were ueed to characterize the pure C60 samples. 相似文献