共查询到20条相似文献,搜索用时 15 毫秒
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M. L. Tsai S. H. Chen K. L. Marshall S. D. Jacobs 《International Journal of Thermophysics》1990,11(1):213-223
The thermotropic and optical properties of methacrylate copolymers and chemically modified poly(-benzyl L-glutamate) were investigated as part of our effort to explore the optical applications of these materials. It was found that besides the commonly cited comonomer ratio, physical blending and annealing followed by quenching represent a new and more flexible means to tune the selective reflection wavelength. In the chemically modified poly(-benzyl L-glutamate) system with Tg as low as — 25 °C, it appears that the relatively high-melt viscosity is capable of sustaining the cholesteric mesophase, generated by annealing and quenching, while subjected to heating up to 100°C.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A. 相似文献
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The rise of black phosphorus (BP) as a new family member of two‐dimensional (2D) materials brings new concepts and applications to the field, because of the infrared band gap and anisotropic properties of such materials. Among many excellent properties of BP, the optical property attracts special attention in recent years. Optical methods have been widely and successfully used in characterizing BP, not only to obtain the structural information (such as thickness and crystalline orientation), but also to probe the fundamental properties of BP in terms of the behavior of electrons, phonons, excitons etc. In this Review, a comprehensive understanding about the optical characterization of BP such as Raman, absorption, and photoluminescence is presented. Also, the unique optical properties and applications explored in recent years are reviewed. 相似文献
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Nanoporous polymeric materials are porous materials with pore sizes in the nanometer range (i.e., below 200 nm), processed as bulk or film materials, and from a wide set of polymers. Over the last several years, research and development on these novel materials have progressed significantly, because it is believed that the reduction of the pore size to the nanometer range could strongly influence some of the properties of porous polymers, providing unexpected and improved properties compared to conventional porous and microporous polymers and non-porous solids.In this review, the key properties of these nanoporous polymeric materials (mechanical, thermal, dielectric, optical, filtration, sensing, etc.) are analyzed. The experimental and theoretical results obtained up to date related to the structure–property relations are presented. In several sections, in order to present a more compressive approach, the trends obtained for nanoporous polymers are compared to those for metallic and ceramic nanoporous systems. Moreover, some specific characteristics of these materials, such as the consequences of the confinement of both gas and solid phases, are described. Likewise, the main production methods are briefly described. Finally, some of the potential applications of these materials are also discussed in this paper. 相似文献
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Cross-linked polymers on the basis of di-, tri and tetraglycidyl ethers of quercetin (3,3′,4′,5,7-pentahydroxyflavone) were synthesized, and then, poled in electrical field of corona discharge. Investigations of structural, thermal and optical parameters of the polymer films were carried out. It was found that the polymers obtained from di- and triglycidyl quercetin ethers had high values of macroscopic quadratic susceptibilities and substantial stability of nonlinear optical (NLO) properties after the poling. Tetraglycidyl ether of quercetin forms the polymer of lower quadratic susceptibility, which demonstrates noticeable relaxation process resulting in decrease of the NLO effect.It is supposed that the difference of the NLO properties is due to peculiarities of physical network of the polymers, namely to the ratio between numbers of hydrogen bonds formed by hydroxyl groups of chromophore fragments and by the ones of interfragmental parts of the polymeric chains. 相似文献
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ZHENG Qiang ZUO Min PENG Mao SHEN Lie FAN Yurun 《Frontiers of Materials Science in China》2007,1(1):1-6
Rheological measurement has been a preferred approach in the characterization of the formation and evolu-tion of microstructures for multi-component or multi-phase polymeric material systems owing to i... 相似文献
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The structures and electronic properties of the rings composed of D2d C36 cages are investigated using the semi-empirical AM1 molecular orbital method with full geometric optimization. It is found that most of the converged structures are more stable after the rings are formed. Strain plays an important role in the stability of the fullerene rings. Other factors influencing the stability are also discussed, such as the type of the bonded carbon atoms and the size of retained aromatic domains. Comparison of the structures and electronic properties are made between the C36-rings and those composed of D6h C36 isomers. 相似文献
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利用熔拉法制备了双锥光纤,系统地研究了拉制过程中拉制距离、拉制速度、氢气流量等参数与双锥光纤光学传输特性关系,实验表明,拉制距离控制在30mm-32mm,拉制速度在0.15mm/s,氢气流量在140-150之间时,可以得到损耗在0.5dB-0.7dB,锥腰直径介于0.6μm-2.5μm的低损耗双锥光纤。利用自行制备的双锥光纤进行微球腔耦合实验,得到微球腔良好的透射谱线。该范围内的双锥光纤可以高效激发微球腔回廊模式,对微球腔的应用以及双锥光纤在光传感应用方面具有指导意义。 相似文献
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ZrO2:CdS薄膜的光物理性质 总被引:1,自引:0,他引:1
利用吸收和荧光光谱研究了ZrO2:CdS薄膜的光物理特性.实验观察到了随颗粒尺寸的减小CdS的吸收带边的蓝移现象.研究了不同激发条件下的荧光光谱,发现了薄膜中CdS的微弱的荧光发射.并且分析了介质效应对CdS光学特性的影响. 相似文献
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采用电子束反应蒸发法,(MnO)y(ZnO)1-y(y≥0.3)陶瓷靶作为蒸发源,高心含量的Ar/O2混合气为反应气体,在石英玻璃衬底上生长得到Mn含量超过50%(原子分数)的Zn1-xMnxO薄膜。场发射扫描电子显微镜和X射线衍射测量显示x〉O.5的Zn1-xMnxO薄膜呈单一晶相的立方相、岩盐矿结构。这与采用abinifio方法计算得到的结果一致(作为简化,计算时未考虑Mn的自旋的影响),即对于x≥0.5的Zn1-xMnxO材料体系,其取类MnO的立方岩盐矿结构比取类ZnO的六方相纤锌矿结构更稳定。对石英玻璃基Zn1-xMnxO薄膜的紫外.可见透射光谱测量表明,随着Mn含量从0增大到0.68,Zn1-xMnxO薄膜的光学带隙从3.35eV增大到5.02eV.磁性测量结果表明,所制备立方Zn0.32Mn0.68O薄膜在室温下没有表现出宏观磁性. 相似文献
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Nikolaos Politakos Iñaki ZalakainBorja Fernandez d'Arlas Arantxa EceizaGalder Kortaberria 《Materials Chemistry and Physics》2013
In this work two systems consisting on polyaniline (Pani) doped with simple and small gap C60 fullerenes have been prepared and characterized. Composites with different doping amounts of 1,2,4 and 8 wt% have been analyzed in order to evaluate their structure together with their optical and electrical properties and the effect of fullerene type and amount on them. The shift and change of shape in Fourier transform infrared spectroscopy (FTIR) bands and solid 13C NMR spectroscopy signals showed the presence of interactions between matrix and fullerenes by electron density transfer among them. Optical properties have also been analyzed in terms of ultraviolet (UV) spectroscopy. The blue shift of several bands confirmed the charge transfer. Obtained structures have been analyzed by optical microscopy (OM) showing the different way in which both types of fullerenes have been incorporated into the polymer chains. Finally, conductivity has been measured by the four probe technique, relating obtained values with the structure of the composite and the different degree of crystallinity of simple and small gap fullerenes. 相似文献
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Organic materials can exhibit responsive behavior, including swelling upon exposure to a specific chemical analyte or displaying a switch surface energy in response to a change to external stimuli. The initiated Chemical Vapor Deposition (iCVD) of responsive surfaces facilitates their integration into novel devices and into roll-to-roll processing. Incorporating responsive organic layers into devices creates the ability to transduce chemical or biological events into optoelectronic signals. Additionally, ultrathin, responsive layers enable the design of novel membranes for separation and purification. This work describes the ability to synthesize thermally responsive organic layers by initiated Chemical Vapor Deposition (iCVD). 相似文献
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Conjugated polyrotaxanes are conjugated polymeric semiconductors engineered at a supramolecular level by threading the conjugated moiety into molecular macrocycles, such as cyclodextrins (CD). CD-threaded rotaxanes thus provide a class of model compounds with reduced interchain interactions which enable us to explore the influence of such interactions on the fundamental photophysics of conjugated semiconductors. CD rotaxination also endows these materials with additional sites for functionalization, thus resulting in extremely versatile structures. Our current understanding of the photophysics of these materials is reviewed, both in solid/liquid solutions and in neat films, as a function of the relevant parameters, such as the threading ratio and the concentration, and with the help of rotaxanes incorporating a variety of different backbones. 相似文献
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ZnO纳米线的制备及其光学性能 总被引:1,自引:0,他引:1
采用物理热蒸发ZnS粉的方法,制备出了大规模的线状和棒状ZnO纳米结构.借助扫描电子显微镜、透射电子显微镜、激光拉曼光谱仪以及荧光光谱仪研究了ZnO纳米线的表面形貌、内部结构及其光学性能.结果表明,所得到的ZnO纳米线是六方的单晶结构,而且具有较好的发光性能和良好的结晶性.纳米线长约2~5μm,直径约60nm,其生长机制为气-固(VS)机制. 相似文献
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Y. Z. Peng T. Liew W. D. Song C. W. An K. L. Teo T. C. Chong 《Journal of Superconductivity》2005,18(1):97-103
Co-doped zinc oxide thin films (Zn1–xCoxO) have been deposited on c-plane sapphire substrates by dual-beam pulsed laser deposition. The films have lattice parameters similar to that of ZnO, and the lattice parameters are closely distributed. The films grew along a preferred direction, following the epitaxial relationship Zn1–xCoxO (0001)substrate (0001). Excitonic emission was suppressed at higher Co-dopant concentration in ZnO because of increase in the distortion of host lattice and defects. When more Zn is replaced by Co, more impurity levels are developed within the bandgap, and more defect are generated. Under our experimental conditions, the bandgap of the films tends to increase with increasing dopant concentration. 相似文献