Synthesis of Multiwalled Carbon Nanocoils and their Foundational Property

碳纳米线圈有望成为高性能纳米机电系统和电磁波吸收器的重要组成部分之一。在本研究中，我们研究了碳纳米管生长的催化剂和过程来控制碳纳米管的生长。此外，还研究了cnc的力学性能。CNCs生长的催化剂1)催化剂颗粒的制备我们使用了三个等离子弧枪的组合来制备催化剂，将其逐层沉积或充分混合在衬底上。采用原子力显微镜（AFM）和透射电镜（TEM）对催化剂的详细结构进行了研究。所有元素在700℃退火过程中混合，形成催化剂颗粒（分层或混合）2)。通过改变工艺条件，cnc的产率略有变化。相反，通过改变一种衬底，cnc的产率大大提高。这表明制备催化剂颗粒的表面相互作用对cnc的生长至关重要。电学和机械性能1)电导率和剪切模量CNCs的电导率与贫碳纳米管相当。为了研究剪切模量，我们分别测量了悬臂式cnc谐振频率的长度依赖关系，并将实验结果与有限元法计算值进行了比较。所制备的cnc的份额模量和Q因子分别为~ 50 GP_a和~ 100。结果表明，在~ 1000℃退火后，cnc的剪切模量和Q因子得到了很大的提高，但仍保持了cnc的原始形状。这意味着制备的cnc的低剪切模量和低Q因子源于cnc内部的吸附质或缺陷。

Carbon nanocoils (CNCs) are expected to be one of components for high performance nano-electromechanical systems and electromagnetic wave absorbers. In this study, we have investigated catalysts and processes for the growth of CNCs to control the growth of CNCs. Furthermore, mechanical properties of CNCs were also investigated.1. Catalyst for CNCs Growth1) Preparation of Catalyst particleWe have used a combination of three plasma arc guns to prepare the catalysts, which were deposited layer-by-layer or well mixed states on a substrate. Detailed structures of catalysts were investigated by AFM and TEM. All of elements were mixed during the annealing process at 700℃ and were formed catalyst particles for both cases gayer-by-layer or mixed).2).High Yield Synthesis of CNCsYield of CNCs were slightly changed by changing the process conditions. On the contrary, yield of CNCs were greatly improved by changing a kind of substrates. This indicates that the surface interaction for making the catalyst particle is very crucial for the growth of CNCs.2. Electrical and Mechanical Properties1) Conductivity and Shear ModulusConductivities of CNCs were comparable to those of poor carbon nanotubes. To investigate the shear moduli, we have measured the length dependence of the resonant frequency of cantilevered CNCs individually and compared the experimental results with computed values obtained by a finite element method. The share moduli and Q factor for the as prepared CNCs were estimated to be〜50 GP_a and〜100, respectively.2) Structural Change by AnnealingIt was revealed that the shear moduli and Q factors of CNCs were much improved by annealing at〜1000℃, where the original shapes of CNCs were remained. This implies that low shear modulus and low Q factor for as-prepared CNCs originate from the adsorbate or defects inside the CNCs.