钽粉的低温掺氮及氮在钽中的分布

叙述了钽粉在镁还原脱氧后引入氮气对钽粉进行掺氮,在200℃以下0．1MPa以上,保温时间大于2h时,得到的钽粉粒子间含氮差别率在20％以下。用俄歇电子能谱仪对渗氮的钽表面进行元素分布研究,发现氮在钽中分布是不均匀的,对于每个粒子也是外表面氮浓度大于钽内部的氮浓度。     

掺Ag含量对金刚石薄膜场发射性能的影响

采用电泳沉积的方法在钛基体上沉积了不同含量Ag纳米颗粒掺杂的金刚石复合薄膜,利用扫描电子显微镜、X射线衍射光谱和拉曼光谱对样品的结构和形貌进行表征,最后进行场发射特性的测试。SEM试验结果表明,制备得到的薄膜连续、致密且纳米颗粒均匀的分布在其中。场发射测试结果显示样品的场发射性能随着复合膜中Ag含量的增加呈现先增强后降低的趋势,在Ag纳米颗粒的掺杂含量为7.5 mg （0.18 g/L）时,复合膜的场发射性能最优。此时,开启电场（E₀）低至1.55 V/μm,在1.96 V/μm的电场强度下可以得到22.69 μA/cm²的场发射电流密度,这表明适量的Ag纳米颗粒掺杂可以显著提升样品场发射性能。同时,文中结合F-N理论进一步讨论了Ag纳米颗粒掺杂含量的变化对金刚石场膜发射性能影响的作用机理。     

碳纳米管对LaNi5稀土合金电化学性能的影响

采用LaNi5稀土合金作为催化剂，用化学气相沉积法(CVD)制备了碳纳米管。研究了含有5％碳纳米管的LaNi5稀土合金电极样品的电化学性能。测定了碳纳米管电极的电化学储氢性能。实验发现：含有碳纳米管的LaNi5稀土合金的电化学放电容量更高，当放电电流密度为100mA／g时，其电化学储氢量高达385mAh／g。其循环寿命也得到了较大改善。循环100次，放电容量仅下降15％。     

碳纳米管/四氧化三铁复合材料的磁性能和电催化性能

采用水热法制备碳纳米管(MWCNT)/四氧化三铁(Fe3O4)复合材料,运用透射电子显微镜(TEM)、X射线衍射(XRD)、傅立叶红外吸收光谱(FTIR)、振动样品磁强计(VSM)以及循环伏安法等对复合材料的微观结构、磁性能以及电化学行为进行研究和分析。结果表明:在MWCNT/Fe3O4复合材料中,磁性Fe3O4纳米颗粒能够对MWCNTs表面较好的包覆,实现了Fe3O4对MWCNTs的表面修饰;Fe3O4含量(质量分数)为62.5%的复合材料容易被磁化,常温下其饱和磁化强度(Ms)为35.89 A·m2/kg,矫顽力(Hc)为0.19 A/m,表现出良好的顺磁性;MWCNTs/Fe3O4修饰玻碳(GC)电极对H2O2的电化学响应具有良好的促进作用,使其氧化还原过电位升高,氧化峰值电流显著增强。     

高温热处理对镀镍碳纳米管电磁性能的影响

通过化学镀的方法制得了Ni-P碳纳米管复合粉体,分别在400℃和700℃对所得的样品进行热处理.分析了复合粉体的物相和形貌,测试了复合粉体的电导率和电磁参数,结果表明:高温热处理后镀层由非晶态的Ni-P转化为立方体的Ni和Ni3P;热处理后样品的透射电镜明显可见10～50 nm大小的镍颗粒附着在纳米管的表面;复合粉体热处理后的电导率和磁化强度增大,获得了较好的电磁参数.高温退火是进一步提高其电磁性能的有效方法.     

可见光响应掺氮TiO2的制备及对白血病HL60细胞体外杀伤效应的研究

采用硫酸钛与氨水反应制备掺氮TiO2。UV-Vis漫反射谱研究表明掺氮的TiO2在紫外区的吸收边明显红移（约20nm），并且在400nm-530nm出现新的吸收区域，光吸收阈值从380nm扩展到530nm。XPS分析表明，在TiO2掺杂的N为间隙态，而且还存在大量的氧空位。氧空位在导带下形成的窄带使得掺氮的TiO2在400nm～530nm出现新的吸收区域。用MTT法测量了掺氮TiO2杀伤白血病HL60细胞的活性。结果显示，无论有无可见光照射，掺氮TiO2对白血病肿瘤细胞杀灭效果明显好于未掺杂TiO2。     

氧化铁/氮掺杂碳纳米管催化剂的制备与氧还原性能研究

目的探索非贵金属作为燃料电池阴极催化剂的氧还原性能。方法采用磁控溅射的方法,在N2/Ar工作气氛中,将Fe溅射到碳纳米管阵列表面,同时将氮掺入样品中,然后在不同温度下退火制备氮掺杂碳纳米管负载氧化铁(Fe_2O_3/N-CNT)的氧还原催化剂。采用场发射扫描电镜、X射线衍射仪、X射线光电子能谱仪对样品的形貌、结构和成分进行分析。通过电化学测试研究样品的氧还原催化性能,并对样品的催化反应动力学进行研究。结果退火温度对样品的形貌和氧还原催化性能具有显著影响,样品的氧还原催化活性随着退火温度的升高先增强后显著下降。其中450℃退火的样品表现出最佳的催化性能,该样品在0.1 mol/L KOH溶液中的起始电位和峰电位分别为0.715 V和0.6 V,电子转移数在3.3~3.6之间。结论 Fe_2O_3/N-CNT具有较好的氧还原催化活性,其中吡啶氮是可能的氧还原催化活性位点。实验中催化剂的制备方法简便且成本低廉,是一种有望替代Pt基贵金属的电催化材料。     

掺废渣混凝土抗冻融性能的超声检测

用超声波法检测了掺废渣混凝土在水溶液、3．5％氯化钠溶液以及3．5％氯化钠与5．0％硫酸钠复合溶液中冻融前后的声速变化。结果表明，生态混凝土在氯化钠溶液中冻融循环的质量损失比水和复合溶液中冻融循环的质量损失大，氯化钠溶液对生态混凝土冻融循环产生的剥蚀是不能忽略的；声速变化比质量损失变化明显，说明超声波法是一种检测混凝土冻融损伤的简单可靠的方法。     

射频磁控溅射方法制备掺氮TiO2薄膜及其结构和亲水性研究

本文采用磁控溅射方法制备掺氮TiO2薄膜。将TiO2作为靶材,通以N2/Ar混合气体来精确控制N的掺杂量。为改善掺氮TiO2薄膜的性能,首先将试样放于退火炉中退火,退火温度范围为300-600℃;再将试样放于黑暗处一段时间;最后用可见光（visible-light, VIS）照射。采用扫描电子显微镜（Scanning electron microscopy, SEM）观察薄膜的表面形貌,结果表明,颗粒尺寸随退火温度升高而增大。采用X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）研究薄膜的化学成分,结果表明,薄膜中生成了N-Ti-O (β-N)和羟基,这可能是因为N掺杂入TiOx晶格引起的;且羟基含量随退火温度升高而增加,使得基片有更好的亲水性。采用X射线衍射（X-ray diffraction, XRD）研究薄膜的晶体结构,结果表明,退火后非晶薄膜转变为晶态。采用接触角仪测试薄膜的亲水性,结果表明,水接触角随退火温度升高而减小,这可能是由于颗粒尺寸和羟基含量的改变造成的。亲水性也受避光储存时间的影响,实验结果表明,随着储存时间的增加,水接触角增加。可见光照射实验表明,可见光照射后薄膜的亲水性增加。     

多壁碳纳米管复合BiSbTe材料的热电性能

研究了BiSbTe/多壁碳纳米管(MWCNTs)复合材料的球磨法制备及其热电性能(300~500 K)。采用商用BiSbTe块体作为基体材料,利用球磨及压力辅助的感应加热烧结进行致密化得到了不同复合比的BiSbTe/0.5、1.0 vol% MWCNTs复合材料。复合MWCNTs后,引入的纳米复合结构增强了声子散射,大幅降低了热导率,同时由于载流子散射的增强和较低的致密度使电导率恶化。尽管电导率降低但热导率得到抑制,BiSbTe/1.0 vol% MWCNT复合材料的热电优值与BiSbTe基体接近。结果表明,优化加工参数获得更高的致密度可以优化BiSbTe/MWCNTs复合材料的热电性能。     

Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

Mg/Fe oxide nanotubes decorated with nitrogen-doped carbon nanotubes (CN_x) were fabricated by catalytic chemical vapor deposition of ethylenediamine on the outer surface of oxide nanotubes. Mg/Fe oxide nanotubes were prepared using a 3:1 molar precursor solution of Mg(NO₃)₂ and Fe(NO₃)₃ and anodic aluminum oxide as the substrate. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The XRD pattern shows that the oxide nanotubes are made up of MgO and Fe₂O₃. TEM and SEM observations indicate the oxide nanotubes are arrayed roughly parallel to each other, and the outer surface of oxide nanotubes are decorated with CN_x. XPS results show the nitrogen-doped level in CN_x is about 7.3 at.%. Magnetic measurements with VSM demonstrate the saturated magnetization, remanence and coercivity of oxide nanotubes are obvious improved after being decorated with CN_x.     

Cathodoluminescence from organic bilayer induced by field electron emission of carbon nanotubes

We report the observation and studies of cathodoluminescence (CL) of organic bilayer structures, such as tris-(8-hydroxyquinoline) aluminium (Alq3) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) deposited on ITO-coated glass, with and without hole transport layer, N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-phenyl)-4,4′-diamine (α-NPD). To excite the CL of such bilayer organic heterostructure, low energy electrons field emitted by single walled carbon nanotube cathodes were utilized. The dependence of CL spectrum and intensity on voltage (V), current (I), type of transport layer and the cathode–anode geometry has been studied. We propose carbon nanotubes as efficient cathodes for stable CL emission from organic multilayer heterostructures. The role of both electron and hole transport layers on stability and spectrum of CL is also discussed.     

Mechanical property enhancement of kinetic sprayed Al coatings reinforced by multi-walled carbon nanotubes

Significant mechanical property enhancement was observed when kinetic sprayed (KS) Al coatings were reinforced by the addition of multi-walled carbon nanotubes (MWCNTs). Embedding the MWCNTs in a ductile Al matrix through mechanical milling to fractions of 0.5 and 1.0 wt.% led to significant improvements in elastic modulus, micro-hardness, and wear resistance. Reinforcement of the Al matrix with MWCNTs is based on the mechanical interaction of MWCNTs with the Al, i.e. elastic wave reflection and dispersion hardening and toughening. These effects were able to overcome the innate ductility of the Al, thereby widening the potential applications of Al coatings. This study provides insight into the strengthening mechanisms of KS MWCNT reinforced Al composite coatings with respect to the spray process, microstructure and mechanical properties.     

空气氧化对球磨后纳米碳管场发射特性的影响

以乙炔为原料气,采用铬一镍复合催化剂,在550~C下,由化学气相沉积法(CVD)制得了直径为20.300nm的多壁碳纳米管(MWNT).经过45min的高能球磨处理后,通过空气氧化法对所获碳纳米管进行提纯,去除了碳纳米管中的无定形碳、碳纳米颗粒等非晶碳成分,提高了碳纳米管的纯度;并研究了提纯温度和场发射特性的关系.用扫描电镜、Raman光谱对其形貌和结构进行了表征.结果表明:碳纳米管在空气中,400～450℃加热10min后,非晶碳成分基本去除,纯度得到提高可以得到优化的场发射特性,如低的阈值电场和高场发射电流等.     

Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 μA/cm²) achieved at a low applied field (3.50 V/μm) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.     

电流对碳纳米管增强铜基复合材料载流摩擦学性能的影响

采用粉末冶金方法在相同的工艺条件下制备纯铜和碳纳米管含量为10%（体积分数）的铜基复合材料。在一种销盘式载流摩擦磨损试验机上考察了不同电流条件下2种材料的载流摩擦磨损性能。结果表明：纯铜和铜基复合材料的摩擦系数和磨损率均随电流的增大而增大,但是电流对纯铜材料的影响更加显著;纯铜材料的主导磨损机制是电弧烧蚀磨损,而铜基复合材料的主导磨损机制是塑性流动变形;碳纳米管可以改善铜基复合材料的载流摩擦磨损性能。     

Influence of pretreatment conditions of Ti film on field emission properties of carbon nanotubes films

Carbon nanotubes (CNTs) films have been synthesized from methane and hydrogen gas mixture by microwave plasma chemical vapor deposition (MPCVD) on Ti-coated Al₂O₃ substrates, which mechanically grinded by SiO₂ powder with Fe dopant. It is found that the grindness is a crucial effect to produce CNTs. By varying pretreatment conditions of the substrates such as no grinding, grinding and grinded acidly washing, the grinding and acidly washing can lower the turn-on field and improve the emission current density and emission light dots. The current density of the un-pretreated sample attains 0.015 mA/cm², but the grinding sample and grinded acidly washing sample attain 12.6 and 3.8 mA/cm², at the electric field of 3.7v/μm, respectively. The grinding sample shows the excellent field emission properties.     

Functionalization of multiwalled carbon nanotubes and related polyimide/carbon nanotubes composites

A low molecular weight tree-type polyimide was used to modify the surface of multiwalled carbon nanotubes. The modified carbon nanotubes exhibited excellent dispersion in organic solvent; and the polyimide/carbon nanotubes composite film basic on such carbon nanotubes shows enlarged combination property compared with the composite film from acid-carbon nanotubes. Meanwhile, an electric conductivity was introduced to the composite film, and the thermal properties have also been developed.     

Properties of copper/graphite/carbon nanotubes composite reinforced by carbon nanotubes

Electroless Cu plating was used for flake G powder and CNTs, Cu-G-CNTs (copper/graphite/carbon nanotubes) composites were manufactured by means of powder metallurgical method. The influences of CNTs on the mechanical properties, conductivity properties, friction, and wear performance of the composite were examined. The results indicate that adding a small amount of CNTs can improve comprehensive property of the composites, especially mechanical property. However, excessive CNT, which is easily winding reunion and grain boundary segregation, results in performances degradation.     

Linearly joined carbon nanotubes

Linearly joined carbon nanotubes (CNTs) have been fabricated on well-ordered porous anodic aluminum oxide (AAO) nanotemplates prepared by a multi-step anodization and pore widening process. The location and shape of the junctions are very uniform. The electronic properties of the tubes will be affected critically by the junctions. Therefore, one could design CNTs which have specific properties by changing the ratio of the two diameters of linearly joined CNTs. The linearly joined tubes could be used in fabrication of nanoscale electronic devices like field-effect transistor (FET).