【作者】 李昊明；

【导师】 姜修道；

【作者基本信息】 长安大学 ， 材料学， 2008， 硕士

【摘要】 纳米科学与技术从20世纪中后期出现发展至今,已经在信息、材料、能源、环境、生物、农业、国防等领域引起了广泛的关注,并被认为是21世纪最重要的科学技术之一。随着科学研究和技术应用的深入,拥有创造这样微小结构的能力已经显得至关重要。本文研究了纳米管家族中的新秀——蛇纹石纳米管。以煎茶岭地区纤胶蛇纹岩中的天然纳米管为例,通过透射电镜观察该地区的蛇纹石纳米管,发现其外径在25nm至45nm之间,内径在12nm至25nm之间。管内中空,管端很少有封闭的现象。同时观察了较为少见的隐晶质的纤蛇纹石纳米管,这种天然蛇纹石纳米管与普通的纤蛇纹石纳米管有所不同。使用简便的水热合成法制备了单分散硫化镉纳米颗粒,该方法最大的优点就是易实施低成本。同时利用透射电子显微镜观察颗粒的粒径分布在10 nm左右,其分散程度较好。利用X射线粉末衍射分析其结晶程度,结果表明硫化镉的结晶程度很不好,基本上是无定型的。分析原因是因为合成温度不够高,无法达到硫化镉的理想结晶温度。但对试样进行光致发光光谱研究,发现其发光性能很好。说明结晶程度是硫化镉纳米颗粒发光性能的一个主要影响因素,但不是决定性指标。最后将单分散硫化镉纳米颗粒注入到蛇纹石纳米管中,组装得到介孔纳米体系。对试样进行了透射电子显微镜观察,得知硫化镉纳米颗粒在蛇纹石纳米管里为线状点链。光致发光光谱研究表明,组装成的纳米体系的发光性能进一步提高,这是介电限域效应和量子尺寸效应共同作用的结果。更多还原

【Abstract】 Nanometer (nm) scale structures represent an exciting, challenging and rapidly expanding area of research that crosses the borders between many disciplines of sciences and engineering.One-dimensional nanostructures, e.g. nanowires and nanotubes, are playing a special role within the realm of nanoscience and nanotechnology. With decrease in size of nanowires or nanotubes, singularities in the electronic density of states develop at special energies. The density of states becomes very large, appearing to be very different from that of crystalline solids or even two dimensional systems. Zero-dimensional materials, like quantum dots and semiconductor nanoclusters, have been showing distinct electronic structures from their bulk counterparts, and exhibited novel optical properties. One-dimensional materials, representatively serpentine nanotubes are expected to show novel properties.The discovery of serpentine nanotubes in the chrysotlie-serpophite rock was reported. Transmission electron microscope (TEM) images show that the nanotubes are multiwalled. Rarely nanotubes appear capped. Their lengths and inner diameters range from 100 to 1000 nm and 12 to 25 nm, respectively.CdS nanoparticles were synthesized by using an aqueous precipitation method; this method is simple, fast and can be developed at room temperature. The obtained particles were characterized using TEM and spectroscopic techniques. TEM images show well dispersed particles and The particle size was 15 nm. This particle size produce a quantum confinement observed in an increment on the band gap value. CdS nanocrystals show an emission band with a maximum in 531 nm.Nanosystem have been formed by the infiltration of CdS nanoparticles into nanotubes of serpentine. Photoluminescence of these templated nanowires was studied under the excitation of the light from a xenon lamp at 400nm wavelengths. Strong interactions of nanoparticles with structural defects of the template were observed. The efficiency of emission in a semiconductor can be improved by forming nanosystem due to the combined effect of the quantum and dielectric confinement. Semiconductor nanoparticles represent emitters with high quantum efficiency. Arranging them in nanotubes can lead to further emission improvement by exploiting the dielectric confinement factor.更多还原