等离子体气相沉积非晶SiO2薄膜的特性研究

用傅立叶红外吸收光谱，电子自旋共振，表面台阶仪等研究了等离子体增强气相沉积法制备的非晶ＳｉＯ２薄膜的特性与膜厚的关系。当膜厚从０．１μｍ递增到１．１μｍ时，１０６０ｃｍ＾－１附近的Ｓｉ－Ｏ－Ｓｉ伸缩振协吸峰从１０５０ｃｍ＾－１漂移到１０７５ｃｍ＾－１，但是８００display status     

离子束溅射沉积作用下聚四氟乙烯膜的制备和结构分析

本文首先利用离子束溅射聚四氟乙烯靶材的方法制备了薄膜，进而研究了其结构。由ＸＰＳ的结果可知，所得薄膜主要由ＣＦ２结构组成；由ＦＴ－ＩＲ的结果可知，在１１６９ｃｍ＾－１和１０８３ｃｍ＾－１处出现了Ｃ－Ｆ的最强吸收峰，在７３４ｃｍ＾－１，６１９ｃｍ＾－１和５００ｃｍ＾－１处出现了聚四氟乙烯的特征吸收峰。ＸＰＳ和ＦＴ－ＩＲ的结果是一致的，所得薄膜呈现聚四氟乙烯的结构特征。     

氮对纳米硅氮薄膜晶化的影响

在电容式耦合等离子体化学气相沉积系统中，用高氢稀释硅烷和氮气为反应气氛制备纳米硅氮（ｎｃ－ＳｉＮｘ２Ｈ）薄膜，结果表明，当Ｎ２／ＳｉＨ４气体流量比（Ｘｎ）从Ｉ增加为４时，薄膜的晶态率从５８％降至１４％，晶粒尺寸从１０ｎｍ降至５ｎｍ，Ｎ／Ｓｉ含量比从０．０３增至０．１２，当Ｘｎ≥５，则生成非晶硅氮（ａ－ＳｉｕＮｘ２Ｈ）薄膜，当Ｘｎ从１增加为１０时，薄膜暗电导率从１０＾－５（Ωｃｍ）＾－１降至１０＾－     

固相法合成氟化石墨

在４５０℃，０．５ＭＰａ的Ｎ２中，固态聚四氟乙烯与石墨（粒度〈４０μｍ，含碳〉９９．７％）合成反应制得灰白色氟化石墨，其真密度为２．５０Ｍｇ．ｍ＾－３，电阻率为２．８５ｋΩ．ｃｍ，在波数１２１９ｃｍ＾－１和１５３０ｃｍ＾－１处有Ｆ－Ｃ供价键红外光谱吸收峰，这些特征与“气相法”合成的氟化石墨一致，“固相法”新工艺方法简单，安全，成本低，无需剧毒单质氟气作为主要原料。     

在Ag基体上用MOCVD法连续制备YBCO超导带

用ＭＯＣＶＤ法在Ａｇ基体上以－１５ｃｍ／ｈ的带速连续制备ＹＢＣＯ超导带，在８００－８５０℃之间沉积的样品均呈强裂ｃ－轴取向；而在７５０－８００℃间，ｃ－轴取向明显减弱，前者为不规则排列的大片状晶结构，而后者为不规则排列的小棒状晶和发育不育的片状晶，或者为小粒状晶集，所制亲品的Ｊｃ（７８Ｋ，ｏ）一般在０．５－１×１０＾４Ａ／ｃｍ＾２之间，最好的达到１．４×１０＾４Ａ／ｃｍ＾２。     

NH3-MBE生长极化场二维电子气材料

介绍了用ＮＨ３－ＭＢＥ技术在蓝宝石Ｃ面上外延的高质量的ＧａＮ单层膜以及ＧＮ／ＡｌＮ／ＧａＮ极化感应二维电子气材料。外延膜都是Ｎ面材料。形成的二维电子气是“倒置二维电子气”。ＧａＮ单层膜的室温电子迁移率为３００ｃｍ＾２／Ｖｓ。二维电子气材料的迁移率为６８０ｃｍ＾２／Ｖｓ（ＲＴ）和１７００ｃｍ＾２／Ｖｓ（７７Ｋ）,相应的二维电子气的面密度为３．２＊１０＾１３ｃｍ＾－２（ＲＴ）和２．６ｘ１０＾１３ｃｍ＾     

新型压电材料芳香族聚脲薄膜

用真空蒸发聚合法合成了亚微米厚度的芳香族聚脲薄膜。红外吸收和元素分析表明，沉积原状薄膜处于低聚状态（３－６单体分子），它的香分子化是在热极化或热处理过程中完成的。极化后的聚脲高分子在室温和１０Ｈｚ的频率下测定应力压电常数，应变压电常数，弹性常数，热释电系数，介电常数和介电损耗分别为２０ｍＣ／ｍ＾２，１０ｐｃ／Ｎ，２．２ＧＮ／ｍ＾２，１８μＣ／ｍ＾２Ｋ，４．０和０．００５。芳香族聚脲薄膜的压电和热释     

氧化锌透明导电薄膜的制备及其特性

氧化锌薄膜的透明导电特性与化学计量偏离和溅射条件有关。以２％氧化铝掺杂的氧化锌陶瓷作靶,采用ＦＲ磁控溅射技术制备的透明导电薄膜,其电阻率４．５＊１０＾－３Ωｃｍ,载流子浓度２．８＊１０＾２０ｃｍ＾－３,霍尔迁移率１５．８ｃｍ＾２／Ｖ．ｓ平均透射率大于８０％。     

溶胶—凝胶制备TiO2／SiO2复合薄膜的FT—IR表征

ＦＴ－ＩＲ吸收谱用来研究具有多孔结构的ＴｉＯ２／ＳｉＯ２复合薄膜；薄膜在１２００ｃｍ＾－１有一较强的肩峰，其强度与峰位随热处理温度度而生变化。在９５５ｃｍ＾－１的吸收峰是由于Ｓｉ－Ｏ－Ｔｉ和Ｓｉ－ＯＨ的结果，并随着热处理 度的提高其吸收峰完全是Ｓｉ－Ｏ－Ｔｉ振动所引起的，其峰位随着ＴｉＯ２的增加，向低频区域移动。     

等离子体辅助反应式脉冲激光熔蚀制备AIN薄膜的低温生长

使用等离子体辅助反应式脉冲激光溅射沉积薄膜的方法在Ｓｉ（１１１）和Ｓｉ（１００）基片上已经成功地低温制备出ＡＩＮ多晶膜。实验表明,当脉冲能量密度ＤＥ＝１．０Ｊ·ｃｍ＾－２,脉冲频率ｆ＝５Ｈｚ,氮气气压ＰＮ２＝１．３３×１０＾４Ｐａ,基底温度ｔｓｕｂ＝２００℃,放电电压Ｖ＝６５０,基靶距离ｄｓ－Ｔ＝４ｃｍ时薄膜的生长速度等于６ｎｍ／ｍｉｎ。ＡＩＮ薄膜的折射率为２．０５,和基底的取向关系分别为：ＡＩＮ     

Carbon nanotube-based functional materials for optical limiting

Optical limiting is an important application of nonlinear optics, useful for the protection of human eyes, optical elements, and optical sensors from intense laser pulses. An optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The optical limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent optical limiting responses. In the former case the optical limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real optical limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The optical limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the optical limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the optical limiting. Further improvements in the optical limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by ex situ alignment and other methods. It would be very desirable, from the practical application point of view, if one can design broadband optical limiting chromophores that would function in a multimechanistic fashion.     

Finite element modeling and testing of a deformable carbon fiber reinforced polymer mirror

Thin-shelled composite mirrors have been recently proposed for use as deformable mirrors in optical systems. Large-diameter deformable composite mirrors can be used in the development of active optical zoom systems. We present the fabrication, testing, and modeling of a prototype 0.2 m diameter carbon fiber reinforced polymer mirror for use as a deformable mirror. In addition, three actuation techniques have been modeled and will be presented.     

Polyimide-fullerene nanostructured materials for nonlinear optics and solar energy applications

Based on the model polyimide systems the principal nonlinear optical features, such as laser induced refractive indices changes, nonlinear refraction and third order susceptibility have been established during their doping with fullerenes, shungites, carbon nanotubes, carbon nanofibers, quantum dots, etc. The evidence of the correlation between laser induced refractive indices and charge carrier mobility has been obtained. The features of new nanocomposites for their possible optoelectronics, laser techniques and solar energy applications have been considered.     

Evolution of structural and optical properties of nanostructured silicon carbon films deposited by plasma enhanced chemical vapour deposition

Nanostructured silicon carbon films composed of silicon nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix have been deposited by plasma enhanced chemical vapour deposition technique using silane and methane gas mixture highly diluted in hydrogen. The structural and optical properties of the films have been investigated by X-ray diffraction, Raman, Fourier transform infrared, ultra violet-visible-near infrared and photoluminescence spectroscopies while the composition of the films has been obtained from nuclear techniques. The study has demonstrated that the structure of the films evolves from microcrystalline to nanocrystalline phase with the increase in radio frequency (rf) power. Further, it is shown that with increasing the rf power the size of silicon nanocrystallites decreases while the optical gap increases and a blueshift of visible room temperature photoluminescence peak can be observed.     

Optical limiting threshold in carbon suspensions and reverse saturable absorber materials

I report on the measurement of threshold energy fluence for optical limiting of nanosecond and microsecond pulses in a high-performance carbon suspension known as Defence Research Establishment Valcartier carbon black suspension (CBS)-100. Thresholds as low as 24-mJ/cm(2) (nanosecond regime) and 100-mJ/cm(2) (microsecond regime) have been obtained. The measurement technique, based on an f/20 optical system and a small analysis aperture, has been tested by measurement of reverse saturable absorber materials and other carbon suspensions whose properties can be found in the technical literature. A factor of merit has emerged from these measurements that could be used to order by limiting performance the different types of carbon suspension. In this ordering, CBS-100 appears as the best choice in the set of suspensions tested for short and long pulses.     

The effects of pressure on the carbonization of pitch and pitch/carbon fibre composites

Three pitches which give carbons of varying optical texture have been carbonized singly and with different carbon fibres at pressures in the range 0.1 to 200 MPa. The effect of pressure on the carbonization system is to retard growth and coalescence of the growth units of mesophase, thus reducing the size of the optical texture of the resultant carbon. With increasing pressure botryoidal (spherical) structures are formed. On co-carbonization of pitches with carbon fibres the alignment of the basal planes of the matrix carbon parallel to the fibre length at the fibre/matrix interface is improved within a given pressure range. This range is dependent upon the parent pitch used and is experimentally determined. This effect is seen for all fibre types.     

碳纳米管的自组装研究进展

用自组装技术组装的碳纳米管具有新奇的光、电、催化等功能和特性，因此具有良好的发展前景。近年来，许多方法已经用于碳纳米管的组装；综述了化学吸附自组装、静电自组装、模板辅助自组装及DNA操纵下的自组装等几种主要的碳纳米管的组装方法，并对各种方法的特点及研究现状进行了评述。     

Direct spectroscopic evidence of energy transfer from photo-excited semiconducting polymers to single-walled carbon nanotubes

Single-walled carbon nanotubes have been efficiently dispersed in an organic solvent using the semiconducting polymers MEHPPV and PFO. It has been found that energy is transferred to the carbon nanotubes when the polymer is photo-excited across its minimum energy gap. This is shown using photoluminescence excitation mapping in the range of both the polymer's and the nanotube's optical absorbance. Possible mechanisms for the energy transfer are discussed.     

Hot-filament CVD synthesis and application of carbon nanostructures

We have reported the catalyst-assisted hot-filament chemical vapor deposition (HFCVD) of various carbon nanostructures, such as carbon nanotube (CNT), nanoparticle (CNP), and nanofiber (CNF), and their application examples. In the case of CNT, vertically aligned high-density growth has been investigated in detail using in-situ optical reflectivity measurement. For CNF showing large field-emission currents, adsorbate-related emission behavior and the emission from patterned cathodes have been studied. Regarding CNP, the performances of a series of triode field emitters with CNP cathodes have been compared, and the application of CNP triode to miniature time-of-flight mass spectrometer has been discussed.     

Crystal growth, structure and characterizations of a new semiorganic nonlinear optical material—β-Alanine zinc chloride

The title compound, β-alanine zinc chloride—a new semiorganic nonlinear optical crystal was grown by slow evaporation technique. Single crystals of β-alanine zinc chloride have been subjected to X-ray diffraction analysis to determine the crystal structure. The powder X-ray diffractogram of the crystal has also been recorded. The amount of carbon, nitrogen and hydrogen in the crystals was also estimated. Fourier Transform Infrared and Raman spectral measurements have been carried out on the grown crystals in order to identify the functional groups. The presence of hydrogen and carbon in the β-alanine zinc chloride was confirmed by using proton and carbon nuclear magnetic resonance spectral analyses. The percentage of zinc in the crystal was determined by atomic absorption spectroscopy. Optical behavior such as ultraviolet-vis-near infrared transmittance spectrum and second harmonic generation has been investigated. The mechanical strength and thermal behavior of the grown crystal have been analyzed.