NER: Controlled Synthesis of Carbon Nantotubes with Desired Properties

提案标题：NER：具有所需性质的碳纳米管的受控合成提案编号：CTS-0508434主要研究员：Renu Sharma研究所：亚利桑那州立大学分析(决定的基本原理)：人们对将碳纳米管用作微机械、扫描探针、纳米电路的组件和生物传感器的元件非常感兴趣，因为它们的结构变化导致了不同的机械和电学性能。合成足够数量的具有目标结构和一系列性质的纳米管仍然是一个挑战。在环境高分辨电子显微镜(ETEM)中，采用原位催化化学气相沉积(CVD)的方法制备了碳纳米管。催化剂也将在同一设备中通过电子束诱导沉积来制备。通过对催化剂分散性和纳米管合成条件的控制，以及在亚纳米尺度上观察和物理表征新兴结构的能力，将获得对纳米管合成过程的新见解。第一性原理电子结构计算结合结构模型，将探索催化剂颗粒取向如何影响生长方向和生长速度。碳在催化剂颗粒中和表面的扩散也将被模拟。研究的目标是阐明如何选择性地合成包括单壁碳纳米管(SWCNTs)在内的理想类型的碳纳米管，选择性地制备碳纳米管将朝着将纳米管用于纳米器件的更广泛目标迈出重要的一步。例如，开发的技术将在平板显示器的场发射体的直接合成或半导体设备的3-D网络的直接合成中具有价值。此外，电子束诱导沉积可用于制备量子点阵列。这里开发的组合催化表征技术也将有助于在典型反应温度下研究原子水平的催化，并将对许多应用的催化剂设计产生影响。展示生长机制的视频电影，与模型相结合，形成了对本科生纳米技术教育以及K-12推广计划的宝贵视觉教具。

AbstractProposal Title: NER: Controlled Synthesis of Carbon Nanotubes with Desired Properties Proposal Number: CTS-0508434Principal Investigator: Renu SharmaInstitution: Arizona State UniversityAnalysis (rationale for decision):There is great interest in using carbon nanotubes as components in micromachines, scanning probes, nanocircuits and as elements of biosensors since their structural variations give rise to a diverse range of mechanical and electrical properties. Synthesis of sufficient quantities of nanotubes with a targeted structure and set of properties is still a challenge. Carbon nanotubes will be synthesized by controlled in situ catalytic chemical vapor deposition (CVD) in an environmental high-resolution transmission electron microscope (ETEM). The catalyst will also be prepared in the same instrument by electron beam induced deposition. With control over the catalyst dispersion and the nanotube synthesis conditions, as well as the ability to observe and physically characterize the emerging structures at the sub-nanoscale, new insights will be gained into the nanotube synthesis process. First principles electronic structure calculations, in conjunction with structural models, will explore how catalyst particle orientation may contribute to the growth direction and growth rate. The diffusion of carbon through and on the surface of the catalyst particles will also be modeled. The research goal is to elucidate ways to selectively synthesize desirable types of CNT including single-walled CNTs (SWCNTs).The selective fabrication of carbon nanotubes would be an important step towards the broader goal of using nanotubes in nanoscale devices. For example, the techniques developed will be valuable in the direct synthesis of field emitters for flat panel displays or 3-D networks for semiconductor devices. Also, electron beam induced deposition can be used to fabricate arrays of quantum dots. Combinatorial catalysis characterization techniques developed here will also be useful for studying catalysis at the atomic level at typical reaction temperatures, and will have impact in the design of catalysts for many applications. Video movies showing growth mechanisms, combined with models, form invaluable visual aids for undergraduate nanotechnology education as well as for a K-12 outreach program.