扫描电镜在喀斯研究中的应用

扫描电镜是了解矿物和岩石的结构、孔隙特性其喀斯特化的有力工具。笔利用扫描电镜及与之匹配的波谱仪、能谱仪、通过对１００多个碳酸盐岩试样的观察，系统研究了其矿物特怔、微观斯特作用机理及喀斯特孔隙类型，并得出结论：（１）表面反应控制下的选择性溶解是微观喀斯特作用的最本质特征；（２）碳酸盐矿物极完善的菱形解理是选择性溶解的优势点；（３）岩石结构控制了喀斯特孔隙的发育和演化。     

系统方法在电镜故障诊断过程中的运用

提出了系统诊断方法：建立完整的电镜功能系统，把握正确的故障特征。可以准确、迅速地将邦联从大的范围逐步缩小到尽可能小的范围内，对于小范围的故障，运用其它方法容易找出故障点所在，因此，系统诊断方法是处理复杂故障的一种快捷、有效的方法。     

TiN膜的电子显微分析

本文是用JEM-2000EX型电镜,对射频等离子体沉积的TiN薄膜进行具体分析,从而得到TiN的形貌及晶体结构。     

电子热运动对电子显微镜分辨本领的影响

本文简述了显微镜的分辨本领,导出了在考虑相对论效应的情况下高速电子束的波长与加强电压的关系,研究了由于电子热运动引起电子液的色散,并研究了该色散对电镜分辨本领的影响,得出了电子热运动引起的色差比加速电压不稳造成的色差还大的主要结论。     

人工加速老化丝织品的纤维损伤性研究

丝织品老化研究是丝织品文物保护的重要内容之一. 采用人工加速老化实验方法制备了光老化、热老化、水解老化和氧化老化的桑蚕丝样品,利用扫描电镜观察了样品的老化程度,对影响桑蚕丝丝织品老化的因素进行了考察,并对桑、柞蚕丝织品的抗水解、抗氧化能力进行了对比分析. 结果表明:加速老化实验方法可以强化老化因素,可用来确定各因素对丝织品老化的影响;光、热、氧化和水解都能对丝织品产生不同程度的老化;桑蚕丝的抗水解、抗氧化能力优于柞蚕丝.     

系统方法在电镜故障诊断过程中的运用

提出了系统诊断方法：建立完整的电镜功能系统，把握正确的故障特征，可以准确、迅速地将故障从大的范围逐步缩小到尽可能小的范围内．对于小范围的故障，运用其它方法容易找出故障点所在．因此，系统诊断方法是处理复杂故障的一种快捷、有效的方法     

离子薄化器及其应用

离子薄化器是近几年来国内开始使用的透射电镜样品制备仪器。本文介绍了离子薄化器在透射电镜样品制备中的应用,结合具体实例对影响薄化速度的因素进行了讨论。并根据实验对离子薄化样品的制备过程、参数的选择、离子薄化样品照片的拍摄和分析做了介绍。     

干酪根及白泡煤的超显微结构的TEM研究

本利用透射电子显微镜的高分辨率、高放大倍数特性及选区电子衍射技术，对干酷根及白泡煤进行了系统的ＴＥＭ研究。重点研究了干酪根及白泡煤中的微粒体及分子定向排列。作论证了微粒体及分子定向延展度是干酪根的类型划分及生油潜力测定的重要依据，并且对煤成烃的研究具有一定的指导意义。     

Catalytic graphitization of polyacrylonitrile-based carbon fibers coated with Prussian blue

Prussian blue (PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile (PAN)-based carbon fibers. PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating (PB content) was controlled by adjusting the electrodeposition time. PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy. The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating. When the PB-coated carbon fibers were heat-treated at 1 900 °C, interlayer spacing (d ₀₀₂) and crystallite size (L _c) reach 0.336 8 and 21.2 nm respectively. Contrarily, the values of d ₀₀₂ and L _c are 0.341 4 and 7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800 °C. Compared with the bare carbon fibers, PB can make the heat treatment temperature (HTT) drop more than 500 °C in order to reach the same extent of graphitization. Furthermore, the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.     

Structures and magnetic properties of nanocomposite CoFe2O4-BaTiO3 fibers by organic gel-thermal decomposition process

The nanocomposite xCoFe₂O₄-(1−x)BaTiO₃ (x=0.2, 0.3, 0.4, 0.5, molar fraction) fibers with fine diameters and high aspect ratios (length to diameter ratios) were prepared by the organic gel-thermal decomposition process from citric acid and metal salts. The structures and morphologies of gel precursors and fibers derived from thermal decomposition of the gel precursors were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. The magnetic properties of the nanocomposite fibers were measured by vibrating sample magnetometer. The nanocomposite fibers consisting of ferrite (CoFe₂O₄) and perovskite (BaTiO₃) are formed at the calcination temperature of 900 °C for 2 h. The average grain sizes of CoFe₂O₄ and BaTiO₃ in the nanocomposite fibers increase from 25 to 65 nm with the calcination temperature from 900 to 1 180 °C. The single fiber constructed from these nanograins of CoFe₂O₄ and BaTiO₃ has a necklace-like morphology. The saturation magnetization of the nanocomposite 0.4CoFe₂O₄-0.6BaTiO₃ fibers increases with the increase of CoFe₂O₄ grain size, while the coercivity reaches a maximum value when the average grain size of CoFe₂O₄ is around the critical single-domain size of 45 nm obtained at 1 000 °C. The saturation magnetization and remanence of the nanocomposite xCoFe₂O₄-(1−x)BaTiO₃ (x=0.2, 0.3, 0.4, 0.5) fibers almost exhibit a linear relationship with the molar fraction of CoFe₂O₄ in the nanocomposites.     

Synthesis and oxidation behavior of boron-substituted carbon powders by hot filament chemical vapor deposition

Boron-substituted carbon powder, B _x C_1−x with x up to 0.17, has been successfully synthesized by hot filament chemical vapor deposition. The boron concentration in prepared B _x C_1−x samples can be controlled by varying the relative proportions of methane and diborane. X-ray diffraction, transmission electron microscopy, and electron energy loss spectrum confirm the successful synthesis of an amorphous BC₅ compound, which consists of 10–20 nm particles with disk-like morphology. Thermogravimetry measurement shows that BC₅ compound starts to oxidize approximately at 620°C and has a higher oxidation resistance than carbon. Supported by the National Natural Science Foundation of China (Grant Nos. 10474083, 50472051, 50532020, 50672081) and the National Basic Research Program of China (Grant No. 2005CB724400)     

Iron Fibers Arrays Prepared by Electrodepositing in Reverse Liquid Crystalline

Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using ＂FeSO4 solution-sodium caprylate-Decanol＂ 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft templates and the synthesized iron ,fibers were characterized by polarizing microscopy, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray microanalysis etc. The experimental results shou that the synthesized iron fibers with a crystal phase grew up in the form of fiber clusters of about 200 nm along the direction perpendicular to the cathode surface. Each cluster was composed of several tens of fibers. The fibers had almost the same length of more than 10μm with a diameter of about 50 nm.     

Straight SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> nanorod Y junctions

Novel straight silicon oxide [SiO _x (1<x<2)] nanorod Y junctions have been synthesized on Si plate by thermal evaporation of mixed powders of silica and carbon nanofibers at 1300°C and condensation on a Si substrate without assistance of any catalyst. The synthesized samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The results suggested that the straight nanorod Y junctions are amorphous and consist only of elements Si and O, and these rods with diameters about 50–200 nm have a neat smooth surface. The growth of such silicon oxide nanorods may be a result of the second nucleation on the surface of rods causing a change in the growth direction of silicon oxide nanorods developed. Supported by the Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing, and the Program of Science & Technology Activity for Chinese Homecoming Fellow Abroad and Research Program of Beijing Key Laboratory for Sensor (Grant No. KM200810772009)     

<Emphasis Type="Italic">In-situ</Emphasis> growth and photoluminescence of β-Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> cone-like nanowires on the surface of Ga substrates

β-Ga₂O₃ cone-like nanowires have been in-situ grown on the surface of gallium grains and films by heating gallium substrates at 750–1000°C for 2 h in air. The controllable synthesis of β-Ga₂O₃ nanowires with different diameters and lengths was achieved by adjusting the heating temperature and time. The as-synthesized products were characterized by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the β-Ga₂O₃ nanowires are single crystalline with a monoclinic structure and have a controllable diameter and length in the range of 30–100 nm and 0.5–1.5 μm, respectively. A possible mechanism was also proposed to account for the formation of β-Ga₂O₃ cone-like nanowires. Photoluminescence spectra of the β-Ga₂O₃ nanowires obtained at different temperatures were measured at room temperature, and a strong blue photoluminescence with peaks at 430 and 460 nm and a weak red photoluminescence with peak at 713 nm were observed. The blue light emission intensity decreases with increasing the reaction temperature, however, the red light emission intensity hardly changes. The blue and red light emissions originate from the recombination of an electron on an oxygen vacancy with a hole on a gallium-oxygen vacancy pair and the nitrogen dopants, etc., respectively. Supported by the National Natural Science Foundation of China (Grant No. 20573072) and Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20060718010)     

Preparation and characterization of nanocomposite MgFe<Subscript>2</Subscript>O<Subscript>4</Subscript>/SiO<Subscript>2</Subscript>

Nanocomposites MgFe₂O₄/SiO₂ were successfully synthesized by the sol-gel method in the presence of N, N-dimethylformamide (DMF). The formation of pure MgFe₂O₄ was confirmed by powder X-ray diffraction (XRD) and electron diffraction. The structural evolution of MgFe₂O₄ nanocrystals was followed by powder X-ray diffraction and IR absorption spectroscopy. The formation of spinel structure of MgFe₂O₄ started at 800 °C, and completed at 900 °C. The transmission electron microscopy (TEM) measurements suggest that the particle sizes increase with the increasing annealing temperature, and the mean particle sizes of the spherical samples annealed at 800 °C, 900 °C and 1 050 °C are ca. 3 nm, 8 nm and 11 nm, respectively. Magnetization measurements at room temperature and 78 K indicate superparamagnetic nature of these MgFe₂O₄ nanocrystals. Funded by the National Natural Science Foundation of China(No. 30771676), the Natural Science Foundation of Jiangsu Province (No. BK20081842), and the Foundation of Nanjing Bureau of Personal for the Returned Overseas Chinese Excellent Scholars     

Synthesis and characterization of VO<Subscript>2</Subscript>/mesoporous carbon composites for hybrid capacitors

VO₂/ordered mesoporous carbon (CMK-3) composites were prepared by solid-state reaction process. The microstructures were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The experimental results showed that the vanadium oxide in the composites was vanadium dioxide (VO₂) with monoclinic structure, which was artificially loaded on the outer surface of CMK-3. VO₂/ordered mesoporous carbon composites present a significantly improved capacitive performance (131 F/g) increased by 40.86% compared to that of CMK-3 carbon (93 F/g). Therefore, as-prepared VO₂/mesoporous carbon composites suggest promising applications in hybrid capacitors.     

Microstructure characterization of 3D C/SiC composites in combustion gas environments

C/SiC composites prepared by chemical vapor infiltration(CVI) were subjected to a stationary loading of 160 MPa in a combustion gas environment with flame temperature of 1300 ℃.Lifetime of C/SiC composites in such environment was measured.Microstructures of the composites after the testing were also characterized by SEM.The experimental results indicate the lifetime of C/SiC composites is average 2.3 hours in combustion gas environments.The combustion gas flow accelerates the damage of carbon fibers and the failure of the composites by speeding up the diffusion of gas reactants and products,destroying the layer of SiO2 on the surface of SiC coating and bringing fused SiO2 inside the composites.The fracture face of C/SiC is uneven,i e,a flat area close to the windward side and a pulling-out of long fibers near the leeward side,which results from the directionality effect of the combustion gas flow.     

Preparation of bioactive calcium phosphate coating on porous C/C substrate by a novel deposition technique

A novel heat substrate technique, high frequency inductive heat deposition （IHD）, was introduced to coat porous carbon materials, C/C and carbon felt to improve their bioactivity. The morphologies, composition and microstructure of the resulting coatings were examined by scanning electron microscopy （SEM）, energy dispersive spectra （EDS）, X-ray diffractometer （XRD） and Fourier transform infrared spectroscopy （FTIR）. The results show that, the calcium phosphate consisted of non-stoichiometric, CO3-containing and plate- like octacalcium phosphate （Ca8-xH2（PO4）6, OCP） could uniformly cover the entire porous surfaces of carbon materials. Good adhesion of the coating to carbon material substrates was observed.