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LIUDe-hua LIAOLei LIJin-chai GUOHuai-xi FUQiang YEMing-sheng 《武汉大学学报:自然科学英文版》2005,10(3):525-528
Nanostructural zinc oxide films have been synthesized via vapor phase growth by heating pure zinc powder. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) results showed that four kinds of morphologies ZnO nanostructures namely nanowires, well-aligned nanorods, nanofeathers and hexagonal nanorods were formed and all of wurtzite structural crystals. The results indicated that the temperature and substrate play an important role in the formation of different morphologies of ZnO nanostructures. The photoluminescence (PL) measurement was carried out for the wellaligned nanorods ZnO sample and blue emission peaks at 420 and 444 nm have been observed at room temperature. And the blue emission mechanism is discussed. 相似文献
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在溶液的pH值接近中性(7.5)、环境温度接近室温(30℃)的条件下,利用液相法合成了分等级CuO纳米片.用扫描电子显微镜(SEM)和X射线衍射(XRD)对CuO纳米片进行了表征,结果显示:合成的CuO纳米片由无数小纳米级粒子组成.合成过程中,间断地用SEM进行检测,研究了CuO纳米片的形成机制.利用UV-vis光谱分析法估计纳米片的能带隙,结果显示:计算的带隙为1.94 eV.这种结构对于气体传感器、锂离子电极材料、场发射装置以及太阳能电池的制造等具有重要意义. 相似文献
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Based on a brief review of the traditional surface patterning research, this article introduces the recent progress in the
research on surface patterning via molecular self-assembly. Because the size scale of molecular self-assemblies is in the
range of 1–100 nm, the method of molecular self-assembly can easily lead to the construction of ordered structures in nanometer
scale, and thus break through the size limit of traditional lithography. Some novel ways of molecular self-assembly for surface
patterning are particularly introduced in this review, including supramolecular architecture at interface, chemisorption of
dendron thoils, and surface aggregation of bolaform amphiphiles. Provided that we know more and more about the basic principles
governing the surface morphology, it is believed that interfacial molecular assembly would be a very competitive supramolecular
technique, and a potential application in many fields such as surface property adjustment, organic patterned devices, surface
molecular recognition, and combinatorial chemistry is greatly anticipated. 相似文献
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提出了一种广义判别正交非负矩阵分解算法。与传统非负矩阵分解算法不同,该算法对目标函数加入了正交约束,保证了低维特征的非负性;也不同于以往的判别非负矩阵分解算法将判别约束加于低维权重上,该算法将判别约束推广到低维特征中,使得低维特征参与模式识别,进一步提高了识别精度。本文给出了算法的推导过程,并将其应用于人脸验证和人脸表情识别。实验结果表明,该算法提高了低维特征的判别能力,具有更好的性能。 相似文献
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通过一种简便的化学沉积的方法,合成了用于电化学超级电容器的纳米锰氧化物材料.采用扫描电镜(SEM)、透射电镜(TEM)和X-射线衍射(XRD)对材料的形貌及其结构进行了表征.通过循环伏安、恒电流充放电以及电化学交流阻抗等对材料的电化学性能进行了测试,结果为:所制备的材料在6 mol *L-1 KOH 的电解质体系中、在5 mV*s-1的扫描速率下具有266 F*g-1的比容量,对比文献报道值150~250 F*g-1有明显的提高,且材料具有较好的电化学稳定性和较长的循环寿命. 相似文献
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作为一种典型的准一维纳米材料,纳米线具有纳米材料所特有的小尺寸效应或纳米曲率效应,经表面修饰的纳米线一般具有不同于普通纳米线的特殊性质.利用实验室发展成熟的透射电子显微镜原位辐照技术,以透射电子显微镜中残留的有机气体分子为前驱体,成功地在纳米线表面可控沉积了非晶碳纳米颗粒和碳纳米棒,以及局域凸起的非晶碳膜并形成局域肿大的同轴结构.实验结果表明,该方法能够方便地通过控制聚焦电子束的束斑尺寸、辐照方式、辐照时间以及辐照位置等参数,在纳米线表面精确可控地沉积各种非晶碳纳米结构,从而实现纳米线的表面可控修饰.对聚焦电子束辐照下基于纳米线的各种碳纳米结构的可能沉积机理作了进一步地探索,并针对透射电子显微镜中如何减少因电子束辐照诱导非晶碳沉积造成的样品污染提出了几点建议. 相似文献