乙醇化学气相沉积法制备多壁碳纳米管

介绍了采用浮动催化剂法，利用乙醇化学气相沉积法制备多壁碳纳米管。采用二茂铁作为催化剂先体，乙醇作为碳源，利用石英基底收集产物。催化剂先体二茂铁的蒸汽在载气的作用下被带到高温区（800℃），二茂铁在高温区分解形成铁纳米催化剂颗粒，这些催化剂颗粒催化生长出多壁碳纳米管。利用扫描电子显微镜、（高分辨）透射电子显微镜对制备的多壁碳纳米管都进行了表征。实验结果表明，制备的多壁碳纳米管均匀性好，石墨化程度较高。     

单根多壁碳纳米管的电学测试

提出了一种制备多壁碳纳米管的简单方法.以乙醇为碳源,利用催化化学气相沉积工艺制备了碳纳米管.用较为简单的设备在较低的反应温度下,在基底上生长了取向多壁碳纳米管阵列.利用扫描电子显微镜内部的纳米操纵仪对单根碳纳米管进行操纵,并测试了单根多壁碳纳米管的电学特性.     

乙醇化学气相沉积法制备多壁碳纳米管

介绍了采用浮动催化剂法,利用乙醇化学气相沉积法制备多壁碳纳米管.采用二茂铁作为催化剂先体,乙醇作为碳源,利用石英基底收集产物.催化剂先体二茂铁的蒸汽在载气的作用下被带到高温区(800℃),二茂铁在高温区分解形成铁纳米催化剂颗粒,这些催化剂颗粒催化生长出多壁碳纳米管.利用扫描电子显微镜、(高分辨)透射电子显微镜对制备的多壁碳纳米管都进行了表征.实验结果表明,制备的多壁碳纳米管均匀性好,石墨化程度较高.     

取向碳纳米管阵列的等离子体复合化学气相沉积法制备

采用热丝和射频等离子体复合化学气相沉积技术,用旋涂法制备负载催化剂的硅片衬底,以CH4为碳源制备出取向碳纳米管阵列薄膜.利用扫描电子显微镜对不同还原时间和不同N i(NO3)2浓度下制备的催化剂基片和取向碳纳米管阵列薄膜进行形貌分析,用透射电子显微镜和拉曼光谱对碳纳米管进行表征.结果表明,在H2-N2气氛中热还原后硅片上的催化剂粒径均匀,排列致密,利用该法制备的碳纳米管为竹节型多壁碳纳米管,管径分布均匀,管长约5μm.碳纳米管阵列薄膜垂直于硅片衬底生长,生长排列均匀致密,具有良好的取向性.     

单根多壁碳纳米管的电学测试

提出了一种制备多壁碳纳米管的简单方法。以乙醇为碳源,利用催化化学气相沉积工艺制备了碳纳米管。用较为简单的设备在较低的反应温度下,在基底上生长了取向多壁碳纳米管阵列。利用扫描电子显微镜内部的纳米操纵仪对单根碳纳米管进行操纵,并测试了单根多壁碳纳米管的电学特性。     

单根多壁碳纳米管的电学测试

提出了一种制备多壁碳纳米管的简单方法。以乙醇为碳源，利用催化化学气相沉积工艺制备了碳纳米管。用较为简单的设备在较低的反应温度下，在基底上生长了取向多壁碳纳米管阵列。利用扫描电子显微镜内部的纳米操纵仪对单根碳纳米管进行操纵，并测试了单根多壁碳纳米管的电学特性。     

SiC纳米晶/非晶复合纳米纤维的制备和场发射性能研究

采用阵列碳纳米管作为模板制备出了SiC纳米晶/非晶复合纳米纤维(以下称SiC纳米纤维),并对其晶体结构、形貌和精细结构使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HR-TEM)进行了表征.比较了SiC纳米纤维和碳纳米管模板的场发射性能,研究了SiC纳米纤维直径的变化对其绝对场增强因子的影响.结果表明:SiC纳米晶/非晶复合纳米纤维具有特殊的"树状"结构,顶端及"树枝"中分布着大量的SiC纳米晶粒.SiC纳米晶粒以及特殊的分支结构增强了SiC纳米纤维的场发射性能,开启场强低至1.1 V/μm,仅为相同直径碳纳米管模板的1/2.随着SiC纳米纤维直径的减小,绝对场增强因子β0呈明显增大趋势.     

乙醇化学气相沉积法制备多壁碳纳米管

介绍了采用浮动催化剂法,利用乙醇化学气相沉积法制备多壁碳纳米管。采用二茂铁作为催化剂先体,乙醇作为碳源,利用石英基底收集产物。催化剂先体二茂铁的蒸汽在载气的作用下被带到高温区(800℃),二茂铁在高温区分解形成铁纳米催化剂颗粒,这些催化剂颗粒催化生长出多壁碳纳米管。利用扫描电子显微镜、(高分辨)透射电子显微镜对制备的多壁碳纳米管都进行了表征。实验结果表明,制备的多壁碳纳米管均匀性好,石墨化程度较高。     

用FeCl3作催化剂先体制备碳纳米结构

以不同浓度的FeCl3溶液作为催化剂先体,利用乙醇催化燃烧法,在铜片上生长出了碳纳米管和碳纳米纤维.讨论了不同浓度的FeCl3催化剂先体对生长碳纳米材料产物和形貌的影响.利用扫描电镜,透射电镜和喇曼光谱对样品的形貌和结构进行了表征.实验结果表明,随着催化剂先体浓度增大,碳纳米材料产量增大,直径呈现增大趋势,其直径范围也逐渐变大.当催化剂先体浓度为0.01 mol/L时,可以制备出直径较小的碳纳米管;当催化剂先体浓度为0.1 mol/L时,可以制备出直径分布均匀的碳纳米管与碳纳米纤维的混合物;当催化剂先体浓度为1 mol/L时,可以制备出直径分布不均匀的碳纳米纤维.     

碳纳米管和金属纳米粒子复合结构的拉曼光谱特性

提出了一种基于碳纳米管和金属纳米粒子的表面增强拉曼基底,并进行了实验研究。采用化学方法制备了单壁和多壁碳纳米管薄膜;利用离子溅射方法在碳纳米管薄膜上形成Au纳米粒子,构成基于碳纳米管和金属纳米粒子复合结构的表面增强拉曼散射基底。对此样品进行了扫描电子显微镜(SEM),反射谱、拉曼谱等表征测试。研究表明,该基底由于碳纳米管极大的比表面积,可吸附更多的金属纳米粒子,增强拉曼散射信号强度。     

Synthesis method and substrate influence on TiO2 films doped with low vanadium content

Titania films doped with low amount of vanadium were deposited on different substrates (microscope glass, microscope glass covered with SiO₂ barrier layer, and silicon wafer with a thermally grown layer of SiO₂) by dip coating from solutions prepared by sol-gel and microwave (MW) assisted sol-gel syntheses. The selected molar composition was 99.95:0.05 which corresponds to 0.03 at% of V. The films were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and Spectroscopic Ellipsometry (SE). The deposited films thermally treated at 450 °C, presented homogeneous and continuous nanostructured surfaces and good adherence to the substrates used. All samples crystallized in anatase phase and have good optical properties. The highest transmission value was obtained for the V-doped TiO₂ films (T > 90%) deposited from solutions prepared by microwaves assisted sol-gel method. Based on the obtained results it was concluded that the method of preparation has higher influence on the properties of the resulted films than the substrates used.     

一种新的测定多壁碳纳米管中无定形碳含量方法的研究

目前,碳纳米管（CNTs）中无定形碳含量的测定方法很多,但由于测试样品方法不完善和样品预处理的方式不同,导致测量结果有较大差别,实验的可重现性也不好。本文对一种新的测定多壁碳纳米管（MWCNTs）中无定形碳含量的方法进行了研究。该方法基于不同形态碳与CO2反应活性的差异,利用CO2柔性氧化法氧化CNTs,采用热重法（TG）测定CNTs中无定形碳含量。并且,结合拍摄CNTs高分辨电子显微（HRTEM）像,证实通过该方法可使粗品中CNTs相和无定形碳相得以区分,达到了对CNTs中无定形碳进行定量分析的目的。本文也讨论了TG测试过程中的各个影响因素。     

碳纳米管团聚结构的电镜研究

纳米聚团床催化裂解法制得的碳纳米管均以团聚体形式存在，本文利用电子显微镜观察了两种碳纳米管团聚体的团聚结构，分散形态及微观结构，研究表明，纳米聚团床催化裂解法制备的碳纳米管具有多级团聚结构，范德华力及缠绕作用共同造成了多级团聚体的形成，细长的碳纳米管分散困难，易絮凝；短小弯曲的碳纳米管易于分散。     

Spray deposited carbon nanotubes for organic vapor sensors

In this article a study of chemiresistor sensors based on Single and Multi Wall Carbon Nanotube films deposited at low temperature by means of a spray technique is presented. A dispersion of nanotube powder in a non-polar 1,2-Dichloroethane solvent was used as starting solution. Electron Microscopy in Scanning and Transmission mode were used in order to verify the morphological properties of the deposited films. The conductivity of carbon nanotubes (CNTs) was measured in two organic solvent vapors environments: 2-propanol and carbon-tetrachloride. The solvents used are characterized by different polarities. The results show that the electrical resistance of the sensors increases when exposed to solvent vapors. Finally the effect of Teflon-like and Melanin coatings on the sensitivity yield is presented and discussed.     

碳纳米管薄膜的电泳沉积与场发射性能

采用电泳法在Si基片上沉积碳纳米管(CNTs)薄膜。研究了电泳极间距、电泳时间及电泳电压等对沉积的薄膜形貌结构与场发射性能的影响。SEM、高倍光学显微镜和场发射性能测试结果表明,保持阴阳极间距为2cm,在100V的直流电压下电泳2min所获得的CNTs薄膜均匀、连续、致密且具有最好的场发射性能,其开启电场强度仅为1.19V/μm,当外加电场强度为2.83V/μm时,所获得的最大发射电流密度可达14.23×10–3A/cm2。     

Characterization and antibacterial capabilities of nanocrystalline CdS thin films prepared by chemical bath deposition

Antibacterial capabilities of nanocrystalline cadmium sulfide (CdS) thin films have been developed against Gram-positive and Gram-negative bacteria in dark and sunlight at 60 °C. For this purpose, a strain of Gram-positive Staphylococcus aureus, and two strains of Gram-negative bacteria (Pseudomonas aeruginosa, and Escherichia coli) were used. The nanocrystalline CdS thin films have been prepared using a chemical bath deposition (CBD) method at different thicknesses (50, 80 and 100 nm). The different deposition parameters including the speed of rotation of substrate, temperature of chemical bath, pH of solution and time of the deposition were optimized. The Polyvinylpyrrollidone (PVP) was successfully used as capping agent in order to stop the agglomeration in the CdS thin films. It was found that, CdS thin films have remarkable antibacterial activity in dark and sunlight and it could be applied as antimicrobial agent in medical field. In order to confirm the crystalline structure of CdS thin films, the polycrystalline nature of the deposited CdS thin films with hexagonal structure was obtained. Furthermore, the structural parameters including lattice parameters, cell volume, the space group, average grain size, dislocation density and the strain have been calculated. The topography and surface roughness of the CdS thin films have been studied before and after the bacteriostatic effect using Scanning Electron Microscopy (SEM). Furthermore, the compositions of nanocrystalline CdS thin films have been evaluated using Energy Dispersive X-ray emission (EDX) and a Transmission Electron Microscope (TEM). Based on the optical measurements in the range of 300–2500 nm, the band gap energy of the prepared CdS thin films was found to be 2.4 eV.     

基于高温扩散的AlGaAs靶制备

基于高温扩散理论,研究了不同温度下Al在GaAs中的扩散情况。利用扫描电子显微镜(SEM)对Al在GaAs中的浓度分布和Al与GaAs的界面进行了表征。结果表明:当扩散温度较低时(650℃),Al在GaAs中扩散较快,可获得较佳的扩散结果。当温度升高后(800℃),GaAs中的As挥发增强,其在Al和GaAs界面处富集,阻碍了Al向GaAs中的扩散。最后根据实验结果,利用Fick定律计算了在650℃下AlGaAs靶的制备时间。     

纯化条件对多壁碳纳米管功能化的影响

分别采用浓HNO3,混酸(浓HNO3与浓H2SO4体积比为1:3)和酸性高锰酸钾法对多壁碳纳米管(MWCNTs)进行了纯化处理。利用超声法用醋酸铜和纯化好的碳纳米管在碱性条件制备了Cu2O/MWCNTs纳米复合材料。通过XRD、FT-IR、XPS、TEM对三种纯化方法所获得的MWCNTs和Cu2O/MWCNTs进行了对比分析。结果表明,酸性高锰酸钾法纯化处理的MWCNTs功能化效果最好,引入的活性基团相对较多且在表面分布均匀。     

Thin-film electroluminescent devices: Influence of Mn-doping method and degradation phenomena

Comparative experiments on ac thin-film electroluminescent (ACTFEL) emitters show the influence of the electroluminescent source material preparation on the L(V) characteristic. The influence on the polycrystalline structure has been investigated by Scanning Transmission Electron Microscopy (STEM). Different types of degradation occurring during sustained operation of the devices are reported and solutions proposed.     

Growth of multi-wall carbon nanotubes with three-dimensional network microstructure

Multi-wall carbon nanotubes (MWCNTs) were grown by spray pyrolysis of acetylene as the carbon source in the presence of Au-Co as catalyst precursors. A high yield of network-shaped carbon nanotubes (CNTs) with further purification has been obtained in the optimal conditions. The optimum synthesis parameters included a synthesis temperature of 700degC, growth time of 30 min, and a flow rate of acetylene and hydrogen of 40 and 300 sccm, respectively. The morphology and structure features of the MWCNTs are characterised using scanning electron microscopy, transmission electron microscopy, energy dispersive spectra, Raman spectroscopy and thermogravimetry analyses.