低能离子束辅助大面积制备纳米点阵列

本工作研究了离子束辅助下在氧化铝模板中大面积制备纳米点阵列的方法.利用此方法,可成功地制备出密度为1.2×1010cm-2、直径高度统一、排列有序的镍和金纳米点阵列.纳米点直径和密度可由氧化铝模板的孔胞参数控制.这种制备方法亦可适用于其他材料,并为研究纳米点的尺度相关特性提供了契机.     

氧化铝模板制备条件的探索

在低温下通过改变第一次和第二次氧化条件尝试性地生长了系列模板,结合扫描电镜(SEM)研究了模板的孔间距和孔径与制备条件的关系.结果表明模板的形貌经两步氧化已达到最佳,孔间距受到第一步氧化的调制,改变第二步氧化的条件可以制备出不同孔径的模板.并在此基础上分析了模板的形成机理.     

基于超顺排碳纳米管技术的冷阴极X射线管研制

冷阴极X射线管是静态CT系统的关键部件。自从超顺排碳纳米管阵列被发现后,其被用于X射线管中的研究就逐渐展开。通过设计一款新的X射线管结构并采用一套新的X射线管制备工艺开展了冷阴极X射线管研制工作。采用乙炔为碳源气,用化学气相沉积法,制备出超顺排碳纳米管阵列;然后将其作为电子源,研制了一种基于超顺排碳纳米管技术的冷阴极X射线管,并对其进行了性能测试。从绘制的I-V特性曲线分析,当栅极电压为2 373 V时,得到最大发射电流为5.0 mA;使用小孔成像法测得的X射线焦点尺寸为0.6 mm×1.6mm。在阳极高压130 k V以下,研制的X射线管工作稳定。本研究为研制脉冲X射线源以及静态CT安检系统奠定了基础。     

Co纳米线阵列的掠入射中子小角散射研究

本文采用掠入射中子小角散射（GISANS）技术,研究了沉积在多孔阳极氧化铝（AAO）模板中的Co磁性纳米线阵列的空间结构,利用计算机软件对GISANS实验进行了理论模拟,并与扫描电子显微镜（SEM）观察的结果进行比较。结果表明,GISANS实验结果、GISANS理论模拟结果和SEM实验结果三者相吻合。纳米线直径约为60 nm,纳米线中心平均距离约为121 nm,垂直于样品表面相互平行排列,在样品平面内呈现出二维局域六角有序排布。本工作证明了GISANS实验技术结合计算机理论模拟,是研究纳米线阵列及类似纳米体系的有力手段。     

直流电沉积制备纳米铜丝阵列

研究采用模板法直流电沉积制备纳米铜丝阵列。基底选用阳极三氧化二铝硬模板,膜底磁控溅射1层薄铜层（1μm以下）做导电底衬,再利用直流电沉积法制备出纳米铜丝阵列。由此工艺所制备的纳米铜丝长度可达50μm左右、直径约为250nm,丝阵含铜量高。讨论了阴极电流密度、阴极电位、模板类型、模板孔径等因素对纳米铜丝生长的影响,为惯性约束聚变（ICF）实验除金腔靶外的其它金属靶的研究提供了一种新方法。     

臭氧氧化改性碳纳米管对铀的吸附性能

通过臭氧氧化改性方法制备含有大量含氧官能团的改性碳纳米管(CNT)。采用有机元素分析、X射线光电子能谱(XPS)元素分析以及Boehm滴定法分别测得样品的表面含氧量、总含氧量以及不同含氧官能团含量,并对产物的比表面积、孔体积和孔径进行测定。结果表明,改性后含氧功能团数量增加了3~7倍,并且这种臭氧改性技术受温度影响显著。然后,考察了改性CNT对铀的吸附性能,对吸附条件进行优化。结果表明,未经改性的CNT样品的吸附效果较差,铀去除率仅为78.0%,而改性后的CNT对铀的吸附效果有显著提高,铀去除率高达95.0%以上,表明含氧量的增加显著提高了改性物对铀的吸附效果。     

用于阵列探测器的多阳极光电倍增管特性研究

测量了两种新型低串扰的可以作为阵列闪烁晶体读出器件的 H5 90 0系列多阳极光电倍增管(MAPMT)的特性。 PMT采用金属通道倍增极结构 ,使其结构紧凑 ,H6 5 6 8和 H6 5 6 8- 10的外形尺寸均为 30 mm× 30 mm× 4 5 mm,只是高压的分压电路不同。测量了它们的增益、单光电子响应、线性范围、一致性、串扰。这种低串扰的特性 ,非常适合作为阵列探测器的光电转换器件。     

微米柱阵列ICF埋点靶的制备

微米柱阵列埋点靶是研究超短激光辐照靶激光吸收效率和等离子体产生过程及发展的1种重要靶型。本文结合采用电子束刻蚀、X射线刻蚀和微电镀等制备金微米点阵列,用CVD方法对阵列间隙填充无应力CH薄膜,用SEM、AFM与白光干涉仪等对制作过程和结果样品进行检测。结果表明,用电子束刻蚀方法制作的掩膜分辨率好、边缘光滑。用同步辐射的X光制作高质量样品,样品点柱高宽比为4,垂直度近于90°,点柱阵列周期为2×2μm,CH层厚约4μm。     

电子束辐照制备微孔阵列聚丙烯膜的研究

采用电子束辐照方法成功制备了微孔阵列聚丙烯(PP)膜,将微孔阵列掩膜覆盖在聚丙烯膜上,在电子束下进行辐照,然后将样品在蚀刻剂中进行蚀刻,即可得到微孔阵列聚丙烯膜,其孔径为200μm.在研究中采用XRD、GPC、DSC等仪器分别测定了不同剂量辐照的PP样品的结晶度和分子量,分析了它们可能存在的内在联系及其对蚀刻工艺的影响,并对不同方法测得的结晶度结果进行了对比;探讨了蚀刻时间、蚀刻温度、蚀刻剂浓度等因素对蚀刻结果的影响;使用电子拉力机测定了不同电子束辐照剂量PP膜的力学性能;采用电子显微镜对制备的微孔阵列聚丙烯膜图案和孔径进行了相关表征.     

碳纳米管/聚丙烯酰胺复合水凝胶的制备及性能

通过活度2.072×1015 Bq、剂量率2 k Gy·h-1的钴-60进行辐照接枝和辐照交联两步法制备了碳纳米管复合水凝胶。使用傅里叶红外光谱(Fourier Transform Infrared spectroscopy,FTIR)、热释重分析(Thermal gravimetric analysis,TGA)、透射电子显微镜(Transmission electron microscope,TEM)、X射线衍射(X-ray diffraction,XRD)、BET比表面积(Brunauer-Emmett-Teller Specific Surface Area)等方法对样品进行了表征。结果显示,改性后的碳纳米管(Carbon nanotubes,G-CNTs)的管壁出现了明显的链段,其傅里叶红外光谱在1 452 cm-1和1 726 cm-1处多了两个吸收峰;碳纳米管复合水凝胶的BET值(30 m2·g-1)比聚丙烯酰胺水凝胶的(12 m2·g-1)提高了一倍多。实验结果表明丙烯酸被成功接枝到CNTs的管壁上。G-CNTs在凝胶中均匀分散,并提高了复合水凝胶的比表面积和机械强度。     

Theoretical study on the carbon nanotube used ashard x—radiation source

Calculations and analyses are made on the interaction between the carbon nanotube and the incident positron of high energy.The results obtained show that it is possible to use carbon nanotube as hard X-radiation source with high intensity and good monochromaticity.     

The effect of ion sputtering of silicon substrates on the catalyst morphology and growth of carbon nanotube arrays

Polished Si substrates are sputtered by He⁺ ions, and carbon nanotube arrays are prepared on the Fe-coated substrates by heat chemical vapor deposition from acetylene. Scanning electron microscopy and atomic force microscopy are employed to examine the morphologies of sputtered substrates, catalyst and carbon nanotube arrays. It is found that ion sputtering is effective in increasing the roughness of Si substrates, and helpful in obtaining higher density Fe catalyst particles and better-aligned carbon nanotube arrays.     

Electron transferring from titanium ion irradiated carbon nanotube arrays into vacuum under low applied fields

Field emission characteristics of carbon nanotube arrays synthesized by thermal chemical vapor deposition on iron ion pre-bombarded silicon substrate are enhanced by titanium ion irradiation. A pronounced degradation of turn-on electric field of 0.305 V/μm and threshold field, of which the lowest value is only 1.054 V/μm, about 0.482 V/μm at the dose of 5 × 10¹⁶ ions/cm² is as an expression of this enhancement. Scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Photoelectron spectrometer and transmission electron microscopy are measured for comparison before and after the Ti ion irradiation of the carbon nanotube arrays, and the results reveal that the formation of carbon nanorod/nanotube heterostructure during ion irradiation plays a dominative role in the promotion of the field emission properties. However, high-dose irradiating transaction on carbon nanotube arrays will exert repulsive effects on the field emission characteristics for the introduction of severe structural damage. Additionally, the longtime eminent stability behaviors under high applied fields have provided a possibility for the potential application of field emission flat panel display or electron emitters based on carbon nanotube arrays.     

低能碳原子通过单壁碳纳米管的计算机模拟研究

利用分子动力学(MD)模拟对低能碳原子通过单壁碳纳米管的运动轨迹进行了研究。通过改变不同的入射条件,得出粒子在横向平面和三维空间中的运动轨迹,结果表明：在满足一定的入射条件时,粒子在单壁碳纳米管中作受制约的运动或作折线或作螺旋线式的运动。     

SiC/SiC composite fabricated with carbon nanotube interface layer and a novel precursor LPVCS

Continuous SiC fiber reinforced SiC matrix composites (SiC/SiC) have been studied as promising candidate materials for nuclear applications. Three-dimensional SiC/SiC composite was fabricated via polymer impregnation and pyrolysis (PIP) process using carbon nanotubes (CNTs) as the interface layer and LPVCS as the polymer precursor. The microstructural evolution of the fiber/matrix interface was studied. The porosity, mechanical properties, thermal and electrical conductivities of the SiC/SiC composite were investigated. The results indicated that the high densification efficiency of the liquid precursor LPVCS resulted in a low porosity of the SiC/SiC composite. The SiC/SiC composite exhibited non-brittle fracture behavior, however, bending strength and fracture toughness of the composite were relatively low because of the absence of CNTs as the interface layer. The thermal and electrical conductivities of the SiC/SiC composite were low enough to meet the requirements desired for flow channel insert (FCI) applications.     

碳纳米管的径向形变和集束效应

用２０ＭｅＶ质子束照射电弧放电生成碳纳米管样品后，用高分辨率透射电子显微镜观察辐照样品，观察到了与辐照有关的碳纳米管的集束现象，三个并行联结构的纳米管的电镜图表明由于范德瓦尔斯力的作用，纳米管内部的碳（００２）层受到挤压，层间距变小，纳米管发生径向形变。     

Intensive irradiation of carbon nanotubes by Si ion beam

Multi-walled carbon nanotubes were irradiated with 40 keV Si ion beam to a dose of 1×10^7 cm^-2. The multiple-way carbon nanowire junctions and the Si doping in carbon nanowires were realized. Moreover, the formation processes of carbon nanowire junctions and the corresponding mechanism were studied.     

Bonding effect on channeling of C ions in a carbon nanotube

The channeling phenomenon of carbon ions in single-wall carbon nanotubes (SWCNTs) is investigated by using the molecular dynamics simulation with analytical potentials.The relationship between the channeling critical angles in the SWCNT and the bonding interaction is analyzed.It was found that,at 200-5000 eV and 10°-20° of incident angle,the ions with the bonding interaction or chemical effect,have decreased dechanneling probabilities and increased critical angles,compared to that of non-bonding ions.So the bonding effect cannot be ignored in the channeling mechanism of carbon ions through a SWCNT.     

Optical absorption of ion irradiated multi-walled carbon nanotube sheets in the visible to terahertz ranges

ecreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.     

Dynamic interactions of fast ions with carbon nanotubes

We used the hydrodynamic model to describe the dielectric response of a multi-walled carbon nanotube to a fast point charge moving paraxially, either inside or outside the nanotube. Calculations are performed for a two-walled nanotube, giving rise to a splitting of the plasmon frequencies due to the interaction between the electron fluids on the two cylinders. The dependences of the projectile stopping power and the self-energy (image potential) on the velocity and the distance from the nanotube axis show interesting features when the projectile velocity matches the phase velocity of the plasmon mode with a quasi-linear dispersion.