Synthesis of Multiwalled Carbon Nanocoils and their Foundational Property

碳纳米线圈（CNCs）有望成为高性能纳米机电系统和电磁波吸收器的元件之一。在这项研究中，我们已经调查了催化剂和工艺的增长CNCs控制CNCs的增长。此外，还研究了碳纳米管的力学性能.用于CNCs生长的催化剂1）催化剂颗粒的制备我们已经使用三个等离子体电弧枪的组合来制备催化剂，所述催化剂以逐层或良好混合状态沉积在基底上。用AFM和TEM研究了催化剂的结构。所有元素在700℃退火过程中混合，形成催化剂颗粒（逐层或混合）。2）CNCs的高产率合成通过改变工艺条件，CNCs的产率略有变化。相反，通过改变一种底物，CNCs的产率大大提高。这表明用于制备催化剂颗粒的表面相互作用对于CNCs的生长是非常关键的。1）电导率和剪切模量纳米碳管的电导率与差碳纳米管的电导率相当。为了研究剪切模量，我们已经单独测量了悬臂式CNCs的谐振频率的长度依赖性，并将实验结果与有限元方法获得的计算值进行了比较。2）退火对结构的影响研究结果表明，在1000℃退火后，纳米碳纤维的剪切模量和Q值都得到了较大的提高，且纳米碳纤维的形状基本保持不变。这意味着低剪切模量和低Q因子的制备CNCs起源于吸附质或缺陷内的CNCs。

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.