电弧法制备洋葱状富勒烯的工艺研究

运用纳米Bi2O3微粒作催化剂，在电弧放电条件下，进行了纳米洋葱状富勒烯大量合成的研究。并用透射电镜对产物的形貌、结构进行了观察与分析。结果表明：纳米洋葱状富勒烯的石墨化程度很高，且直径均匀(约为25nm)，结构较完善；同时伴有单核纳米洋葱状富勒烯向多核纳米洋葱状富勒烯的转变。为洋葱状富勒烯的宏量制备提供了有利线索。     

NaCl担载Fe催化CVD法合成纳米洋葱状富勒烯

以简单的浸渍法制备的NaCl担载Fe作催化剂,化学气相沉积法在400℃下裂解乙炔,并直接将产物于650℃氩气气氛中保温2h,以提高产物的石墨化程度.通过扫描电子显微镜对催化剂进行了表征,结果显示,大多数Fe粒子已被载体氯化钠分散为粒径在10～40nm之间的纳米颗粒;通过高分辨透射电子显微镜和X射线衍射仪对样品进行了表征,结果显示,本实验合成了粒径在20～50nm之间的石墨化程度稍高的内包Fe3C的纳米洋葱状富勒烯.     

洋葱状富勒烯的制备与提纯

采用CVD法制备了洋葱状富勒烯(OLFs),研究了不同工艺条件对OLFs形成的影响,并通过硝酸回流法对得到的粗产品进行了提纯处理.研究结果表明,在相同的反应体系中,采用乙炔作碳源,氩气和氢气的混合气体作载气,制得的OLFs的纯度较高;硝酸处理可有效去除粗产品中碳纳米管、无定形炭和金属催化剂颗粒等杂质,使得OLFs的整体纯度得到提高.     

洋葱状富勒烯的研究进展

详细介绍和分析了洋葱状富勒烯(OLFS)的各种制备、纯化和改性方法,概述了其性能和应用的最新研究进展.OLFS特有的力、电、光、磁、吸附、催化等物理及化学性能,使其在工程、电子信息、能源、生物医学、化学化工、国防等领域有着广阔的应用前景.为此,应进一步围绕OLFS类新型纳米碳材料的制备、表面修饰、功能化、实际应用等各个环节的物理与化学问题进行探索,为该类功能材料的实际应用提供参考依据.     

水下电弧放电法制备洋葱状富勒烯

探索了纯石墨电极在水中放电制备洋葱状富勒烯（Onion-like fullerenes，OLFs）的过程和工艺。用高分辨透射电镜（High resolution transmission electron microscope。HRTEM）对生成的OLFs进行了形貌、结构的观察与表征。分析结果表明制得的OLFs具有各种不同形状的内核。石墨化程度很高，直径分布在5nm～40nm范围内。在一定范围内随着电流强度的增大OLFs的产量和产率都有不同程度的提高。     

Fe@洋葱状富勒烯的拉曼特征

采用化学气相沉积方法制备了Fe@洋葱状富勒烯并采用高分辨透射电镜（HRTEM）、拉曼（Raman）分析对其进行了表征。结果表明：产物粒径稳定在50nm左右，拉曼特征峰相对于HOPG发生了软化，这是由于其特殊的弯曲层状结构造成。     

液苯介质放电制备洋葱状富勒烯

以液体苯(C6H6)为放电介质,石墨做电极,成功地制备了洋葱状富勒烯(Onion-like Fullerenes,OLFs)。重点考察了电流对OLFs产量的影响,利用高分辨透射电镜(HRTEM)和X-射线衍射(XRD)对所得产物进行了表征。结果表明:电流大小是影响OLFs产量的主要因素,所制OLFs直径分布可控制在10nm~30nm范围内。     

煤基纳米洋葱状富勒烯制备及其结构表征

在射频等离子体条件下以煤为原料制备纳米洋葱状富勒烯(Nano-structured Onion—like Fullerenes:NSOFs).高分辨透射电镜(HRTEM)和X射线衍射(XRD)表征结果表明:以煤为原料可大量制备NSOFs,纯度较高,无碳纳米管伴随生成,外观呈准球状或多面体状,内中空,直径分布较均匀,石墨化程度很高,为低成本合成纯净的NSOFs提供了一条新途径.     

水下电弧放电法制备的洋葱状富勒烯的结构表征

采用水下电弧放电法制备了洋葱状富勒烯(OLFs),通过高分辨透射显微镜(HRTEM)、拉曼散射(Raman)和X射线衍射分析(XRD)等分析方法对产物的形貌、尺寸、微观结构及其物相结构进行表征。结果表明,所制备产物其外观呈准球状或多面体状,最外碳层由闭合的、呈波浪状的石墨片构成,且石墨化程度很高。OLFs的直径分布不均匀,从而造成其拉曼谱峰相对于石墨特征峰发生了频移;TGA考察了OLFs的热稳定性,实验表明OLFs在空气中的热稳定性大于600℃,在氩气中能够维持到1000℃以上。     

微波等离子体法合成洋葱状富勒烯的研究

在微波等离子体条件下, 以乙炔炭黑/二茂铁为原料, 低温合成纳米洋葱状富勒烯(Nano-structured Onion-like Fullerenes: NSOFs). 采用HRTEM、Raman和XRD等分析方法对产物的形貌、尺寸、微观结构及其物相结构进行了表征. 结果表明, 以乙炔炭黑/二茂铁为原料可大量合成NSOFs, 其外观呈准球状或多面体状、实心、直径分布均匀, 最外碳层由闭合的、呈波浪状的石墨片构成.     

Tribological property of onion-like fullerenes as lubricant additive

Onion-like fullerenes (OLFs) were generated by arc discharge in water between pure graphite electrodes. The size and crystalline morphology of the generated OLFs were characterized by means of the high-resolution transmission electron microscopy and X-ray diffraction. Furthermore, OLFs were added to base lubricant and the tribological property of OLFs was investigated by using a four-ball type tribometer. The results indicated that the OLFs with diameter about 25 nm were of high degree graphitization. Good friction-reduction property at different additive concentration and applied load as lubricant additive was obtained. The scratches on the worn surfaces become slighter and more uniform with addition of OLFs to the base lubricant. In addition, the tribological mechanism of the sliding-bearing system was proposed.     

Structural properties of microcrystalline Si films prepared by hot-wire/catalytic chemical vapor deposition under conditions close to the transition from amorphous to microcrystalline growth

The structural properties of microcrystalline Si films prepared by hot-wire/catalytic chemical vapor deposition, with various dilution ratios of silane in hydrogen, were investigated as regards to the role of hydrogen. A large surface roughness correlated with a low crystalline nuclei density was observed for microcrystalline Si films deposited near the transition from amorphous to microcrystalline growth. Investigations of hydrogen-related properties suggest the presence of molecular hydrogen in these films. We tentatively propose that the diffusion of atomic hydrogen into the subsurface layer of growing films, which leads to the relaxation of amorphous Si network and to the generation of molecular hydrogen, plays an important role for determining the film properties, besides top surface reactions.     

Coverage properties of silicon nitride film prepared by the Cat-CVD method

The coverage properties of silicon nitride (Si₃N₄) films prepared by the catalytic chemical vapor deposition (Cat-CVD) technique were systematically studied. By increasing the catalyzer–substrate distance, the coverage was improved from 46 to 67% on a 1.0-μm line and space pattern. The etching rate of Cat-CVD Si₃N₄ film measured using 16BHF solution was independent of the deposited position of the micro-patterns deposited, and was approximately 3 nm/min, one order of magnitude lower than that of plasma-enhanced CVD (PE-CVD) Si₃N₄ film. This means that Cat-CVD Si₃N₄ films are denser than PE-CVD Si₃N₄ films, and that the quality at the side wall is equivalent to that on the top surface. That is, Cat-CVD Si₃N₄ films show a passivation effect, which was excellent, even at the side wall of micro-patterns. These results suggest that Si₃N₄ films prepared by Cat-CVD are suitable for the passivation films in microelectronic devices having a step configuration, such as TFT-LCDs and ULSIs.     

纳米洋葱状富勒烯的研究现状及前景

通过述评纳米洋葱状富勒烯的结构、制备、生长机理、纯化、修饰及性能,指出:纳米洋葱状富勒烯具有独特的中空笼状及同心壳层结构,是富勒烯家族的一个重要成员,具有许多特殊性能,有望在能源材料、高性能、高温耐磨材料、超导材料和生物医用材料等领域得到广泛的应用.     

Crystallization by excimer laser annealing for a-Si:H films with low hydrogen content prepared by Cat-CVD

Crystallization by excimer-laser annealing (ELA) for hydrogenated amorphous silicon (a-Si:H) films with low hydrogen content (C_H) prepared by catalytic chemical vapor deposition (Cat-CVD) was systematically studied. From optical microscopy images, no hydrogen bubbling was observed during ELA, even without a dehydrogenation process. As the laser energy density was increased to 300 mJ cm⁻², the full width at half-maximum of the Raman signal from the crystalline phase decreased to approximately 4 cm⁻¹. This value is almost equal to or even smaller than that reported for polycrystalline Si (poly-Si) films prepared from plasma-enhanced CVD (PECVD) a-Si:H films by ELA so far. The average grain size, estimated from scanning electron microscopy, was approximately 500 nm for C_H of 1.3 at.%. On the other hand, the grain size of poly-Si films prepared from PECVD a-Si:H films with a dehydrogenation process was only 200 nm. The technique using Cat-CVD films is expected to be used for fabrication of low-temperature high-mobility thin-film transistors.     

功能化洋葱状富勒烯在裸鼠体内的流动

采用L-半胱氨酸盐酸盐,通过化合接枝法对洋葱状富勒烯进行功能化,合成水溶性L-半胱氨酸富勒烯衍生物。利用扫描电子显微镜(SEM)、X射线衍射(XRD)、红外光谱(IR)、热重分析(TGA)及X射线能谱分析(XPS)对所制样品进行表征。结果表明:L-半胱氨酸富勒烯衍生物表面具有-OH、-NH3等亲水性基团,水溶性良好。裸鼠实验表明,合成的L-半胱氨酸富勒烯衍生物在生物体组织细胞中具有很好的分布,可以顺利溶入生物体体液并具备良好的流动性。     

AlGaN/GaN HEMTs passivated by Cat-CVD SiN Film

We demonstrate the excellent performance of a 140 W AlGaN/GaN HEMT in the C-band, which is passivated by a Cat-CVD SiN film. The interface trap density of the AlGaN surface passivated by Cat-CVD film after NH₃ treatment is 3 × 10¹² cm^− 2, which is the smallest of investigated deposition techniques. The lowest interface trap density achieved by the Cat-CVD technique makes it possible to operate the AlGaN/GaN HEMT in the C-band. We clarify that the Cat-CVD technique is necessary for developing future amplifiers.     

甲烷浓度对金刚石薄膜质量的影响

纳米金刚石薄膜具有优异的性能,已在多个领域获得广泛应用.但微波等离子体化学气相沉积制备的金刚石薄膜质量却严重受沉积工艺的影响,为了深入了解沉积工艺对制备的金刚石薄膜质量的影响,本文详细研究了甲烷浓度对微波等离子体化学气相沉积( MPCVD)金刚石薄膜质量的影响,利用扫描电镜、X射线衍射、拉曼光谱以及原子力显微镜对其进行...