EFFECT OF ELECTRONIC IRRADIATION IN THE PRODUCTION OF NbSe2 NANOTUBES

In this work, we report the production of NbSe₂ (niobium diselenide) nanotubes formed by irradiating NbSe₂ with high doses of electron irradiation. The apparatus used for the irradiation was a 2 MeV Van de Graaff accelerator at the following conditions: voltage 1.3 MeV, current 5 μA, dose rate 25 kGy/min, and total dosage 1000 kGy. These conditions were maintained fixed while irradiation dosage was changed between 100, 250 and 500 Mrad. We observed enormous and very well defined nanotubes with a length of several nm and width of a few nm, which are hollow and capped at one end. As the level of irradiation is increased to 500 Mrad, onion-like structures were observed.     

OPTIMIZATION OF THE ELECTRON IRRADIATION IN THE PRODUCTION OF MoTe2 NANOTUBES

In this paper, we report the study of the production of MoTe₂ (molybdenum ditelluride) samples after a high dose of electron irradition. A 2 MeV Van de Graaff accelerator was used to irradiate the sample at the following conditions: 1.3 MeV voltage, 5 μA current, 25 kGy/min dose rate, and 1000 kGy total dosage. These conditions are maintain fixed while the irradiation dosages were changed to 50, 100, 200, and 500 Mrad. The optimization of the dosage used for the production of MoTe₂ nanotubes was obtained from the analysis of the samples that were examined in a high-resolution transmission electron microscope. The most efficient production of MoTe₂ nanotubes was obtained at the range between 100 and 200 Mrad. A very typical characteristic was obtained for rotated structures with angles of 4, 5, 7, 8, and 12° observed in the diffraction pattern for MoTe₂.     

OPTIMIZATION OF THE ELECTRON IRRADIATION IN THE PRODUCTION OF MoTe2 NANOTUBES

In this paper, we report the study of the production of MoTe₂ (molybdenum ditelluride) samples after a high dose of electron irradition. A 2 MeV Van de Graaff accelerator was used to irradiate the sample at the following conditions: 1.3 MeV voltage, 5 μA current, 25 kGy/min dose rate, and 1000 kGy total dosage. These conditions are maintain fixed while the irradiation dosages were changed to 50, 100, 200, and 500 Mrad. The optimization of the dosage used for the production of MoTe₂ nanotubes was obtained from the analysis of the samples that were examined in a high-resolution transmission electron microscope. The most efficient production of MoTe₂ nanotubes was obtained at the range between 100 and 200 Mrad. A very typical characteristic was obtained for rotated structures with angles of 4, 5, 7, 8, and 12° observed in the diffraction pattern for MoTe₂.     

PRODUCTION AND CHARACTERIZATION OF MoSe2 NANOTUBES BY ELECTRON IRRADIATION

In this work, we report the production of MoSe₂ (molybdenum diselenide) nanotubes formed by irradiating the samples with high doses of electron irradiation. The irradiation was performed on a 2 MeV Van de Graff accelerator at the following conditions: voltage 1.3 MeV, current 5 µA current, dose rate 25 Kgy/min, and total dosage 1 Mgy. We observed well-defined nanotubes of several nm long and few nm wide, which suppose to be hollow and capped at one end. As the level of irradiation was increased to 1 Mgy, elongated onion-like structures were observed.     

PRODUCTION AND CHARACTERIZATION OF MoSe2 NANOTUBES BY ELECTRON IRRADIATION

ABSTRACT

In this work, we report the production of MoSe₂ (molybdenum diselenide) nanotubes formed by irradiating the samples with high doses of electron irradiation. The irradiation was performed on a 2?MeV Van de Graff accelerator at the following conditions: voltage 1.3?MeV, current 5?µA current, dose rate 25?Kgy/min, and total dosage 1?Mgy. We observed well-defined nanotubes of several nm long and few nm wide, which suppose to be hollow and capped at one end. As the level of irradiation was increased to 1?Mgy, elongated onion-like structures were observed.     

PRODUCTION OF CARBON NANOTUBES IN AIR

Carbon nanotubes were produced by plasma discharging of graphite electrodes in air at 1 atm. The combined yield of CNTs and carbon nanoparticles is ～20 wt % relative to the mass of cathode deposits or 14 wt% of graphite electrode consumed. The yields of CNTs and carbon nanoparticles under different inert gas atmospheres, such as He, Ar, N₂, and air were compared.     

PRODUCTION OF CARBON NANOTUBES IN AIR

Carbon nanotubes were produced by plasma discharging of graphite electrodes in air at 1 atm. The combined yield of CNTs and carbon nanoparticles is ∼20 wt % relative to the mass of cathode deposits or 14 wt% of graphite electrode consumed. The yields of CNTs and carbon nanoparticles under different inert gas atmospheres, such as He, Ar, N₂, and air were compared.     

几种纳米管的电子性质

利用紧束缚方法及密度泛函方法研究了几种纳米管的电子性质。     

氦气压力对碳纳米管形成的影响

用热重分析和差热分析研究地流碳弧法中氦气压力对阴极沉积物－含纳米管碳灰中碳纳米管形成的影响，并与Ｃ６０／７０和石墨的ＤＴＡ曲线比较，结果表明：在研究范围内，氦压越高，碳纳米管与碳纳米粒子的比率越高。可用控制氦气压力调整碳纳米管与碳纳米粒子的比例。     

THE EFFECT OF INFORMATION DELAYS IN A PRODUCTION CONTROL SYSTEM

This paper gives the results of computations, for a chosen production control model, yielding the extra costs incurred when information about a change in mean demand level becomes available at some time relative to the time of the change. These extra costs are zero if the information is available from prehistoric times and increase monotomcally as the detection moment shifts to later points of time. Only “jumplike”changes of mean demand level are considered. It is found that the extra costs as a function of the detection moment N approach a linear asymptote for high N. The points of contact of these results with control chart theory, especially the optimization of control charts as a link between predictors and production control, are mentioned.     

矿物在合成纳米炭管中的催化作用

采用了电弧放电方法合成纳米炭管,在使用Ｆｅ、Ｃｏ、Ｎｉ、Ｔｉ、Ｚｒ等金属元素作催化剂的基础上,探索天然矿物－黄铁矿（ＦｅＳ２）、磁黄铁矿（Ｆｅ１－ｘＳ）、方铅矿（ＰｂＳ）、磁铁矿（ＦｅＦｅ２Ｏ４）、刚玉（Ａｌ２Ｏ３）及合成ＦｅＣｌ３、ＮａＣｌ、ＫＣｌ等化合物作催化剂合成纳米炭管的途径,讨论其催化机理。实验说明：用矿物（化合物）作催化剂合成纳米炭管是可行的,并有应用潜力,其催化效果与电子层结构、化合物键性类型、晶体缺陷等密切相关。就催化效果而言,总体上表现出过渡金属元素催化效果优于非过渡金属元素,晶体结构中共价键程度高的化合物（含金属键或改性的共价键的化合物）催化效果好于离子键程度高的化合物。     

Tersoff—Brenner势函数在纳米碳管研究中的应用

介绍一种以键序概念来描述原子间作用的势函数－Tersoff-Brenner势函数表达式和其碳氢系统中的参数化情况,综述了Tersoff-Brenner势函数在单壁纳米碳管的几何结构优化、力学性能、生长机理等理论研究中的应用,并且讨论了这个函数增加长程作用形式,以期能够在单壁在单壁纳米碳管储氢的理论研究中得到应用。     

THE INFLUENCE OF SYNTHESIS PARAMETERS ON THE PRODUCTION OF MULTIWALLED CARBON NANOTUBES BY THE FERROCENE CATALYZED PYROLYSIS OF TOLUENE

A high yield (∼32 wt.%) of multiwalled carbon nanotubes was obtained in an iron catalyzed reaction. This was achieved in the temperature range 800-1000°C under an atmosphere of H₂/Ar by an improved solution injection method in a horizontal reactor using toluene as carbon source and ferrocene as catalyst precursor. The pyrolysis temperature, ferrocene concentration, solution feeding rate and carrier gas flow rate all influenced the yield of carbon nanotubes and the thickness of the aligned carbon nanotube films. The carbon nanotubes was prepared in high purity using optimized pyrolysis conditions.     

THE INFLUENCE OF SYNTHESIS PARAMETERS ON THE PRODUCTION OF MULTIWALLED CARBON NANOTUBES BY THE FERROCENE CATALYZED PYROLYSIS OF TOLUENE

ABSTRACT

A high yield (～32?wt.%) of multiwalled carbon nanotubes was obtained in an iron catalyzed reaction. This was achieved in the temperature range 800–1000°C under an atmosphere of H₂/Ar by an improved solution injection method in a horizontal reactor using toluene as carbon source and ferrocene as catalyst precursor. The pyrolysis temperature, ferrocene concentration, solution feeding rate and carrier gas flow rate all influenced the yield of carbon nanotubes and the thickness of the aligned carbon nanotube films. The carbon nanotubes was prepared in high purity using optimized pyrolysis conditions.     

具有分形特征的碳纳米管束的储氢性能研究

分形学体现了科学与美学的完美结合,在众多领域得到了广泛的应用。该文提出了碳纳米管束的分形结构,并将该结构应用于碳纳米管的储氢问题。研究表明,分形碳管束的储氢体积密度高于普通碳管束,并且,通常只需要1级分形结构就可以得到较好的储氢性能。此外,该文通过对不同分形形式的比较,发现内部包含七个碳管的分形结构的储氢性能最优。     

碳纳米管非金属掺杂对结构和性能影响的研究

通过讨论氮、硼、硅、氟等非金属原子掺杂的碳纳米管,对场电子发射特性的影响。介绍了掺杂在场电子发射、能源电池、气体传感器等领域的研究和应用。掺杂可以增加碳纳米管的缺陷,改变其电子结构。掺杂可使碳纳米管转变为n型半导体或是金属性导体,将提高场发射性能。同时,掺杂亦可使碳纳米管向P型半导体转变,这将不利于场发射性能改善。当场发射性能随着掺杂浓度升高而提高时,存在最佳掺杂浓度值,一旦超出,则场发射性能逐渐下降。因此,研究碳纳米管非金属掺杂具有重要的应用价值。     

紫外光辐照交联对超高相对分子质量聚乙烯纤维结构和性能的影响

在光敏剂和交联剂存在下，用紫外光进行辐照引发对超高相对分子质量聚乙烯（UHMWPE）纤维进行交联改性。从纤维凝胶含量、力学性能、耐热性、蠕变性、粘结性能、结外光谱及扫描电镜（SEM）等测试分析得知，UHMWPE纤维的性能和结构发生了重要变化，其耐热性和抗蠕变性能有了明显的提高，纤维的表面粘结性能得到了改善，同时，UHMWPE纤维保持了原丝的优异的力学性能。     

电子封装塑封材料中水的形态

利用实验和Fick扩散方程模拟塑封材料对水的吸收过程，得到水汽在塑封材料中的扩展系数和饱和浓度，塑封材料中的水分子存在于高分子链围成的微孔洞中，并与高分子聚合物以氢键相连。当塑封材料中水汽浓度达到饱和时，在水分子进入的有效体积内，水汽的密度为标准状态下水蒸气密度的100倍，为液态水密度的8％，这表明在塑封材料中水分子以一种特殊的液态水形态存在。在一定的水汽浓度下，在界面处的微孔洞中水气液两相共存，在两相共存的微孔洞中由于水分子争夺高分子的氢健使高分子与芯片表面的二氧化硅层的结合减弱，逐步扩展形成可以观察到的分层。     

电子束辐照对HDPE/PA6共混体系的影响

通过电子束辐照的方法，在高密度聚乙烯（HDPE）分子链上引入含氧极性基团，增加了HDPE分子的极性，改善了HDPE与PA6的界面相容性，本文通过FT－IR，SEM，接触角、DSC等方法对电子束辐照HDPE／PA6体系的界面相互作用及其对共混体系结构与性能的影响进行了研究，结果表明，HDPE经电子束辐照后，在其分子链上引入了含氧极性基团，提高了HDPE的极性，增加了表面自由能，从而改善了其与PA6界面相容性，随着辐照剂量的增大，PA6分散相的粒径变小，在HDPE基体中的分散更均匀。