碳纳米管Carbon nanotube

碳原子 sp² 杂化，石墨烯卷曲的方向用手性矢量 (n, m) 描述：(n, n) 为扶手椅型，总是金属性；(n, 0) 为锯齿型；其他为手性型。当 n − m 能被 3 整除时为金属性，否则为半导体性。碳纳米管拉伸强度可达约 50–100 GPa，是钢的数十倍，而密度只有钢的约 1/6；沿轴向导热性极好，金属性管可承载很高的电流密度。

Carbon is sp² hybridised, and the direction of rolling is described by the chiral vector (n, m): (n, n) armchair tubes are always metallic, (n, 0) are zigzag and others chiral. A tube is metallic when n − m is divisible by 3 and semiconducting otherwise. Tensile strength reaches about 50–100 GPa, tens of times that of steel at about one-sixth the density; thermal conductivity along the axis is outstanding, and metallic tubes carry very high current densities.

1952 年苏联科学家拉杜什克维奇和卢基扬诺维奇已发表过直径约 50 nm 中空碳丝的电镜照片，但未受重视。1991 年日本电气公司的饭岛澄男在电弧放电产物中用高分辨电镜清晰表征了多壁碳纳米管，引发全球研究热潮。1993 年饭岛和 IBM 的白求恩分别报道了单壁碳纳米管。

In 1952 the Soviet scientists Radushkevich and Lukyanovich published electron micrographs of hollow carbon filaments about 50 nm across, but they drew little attention. In 1991 Sumio Iijima at NEC clearly characterised multi-walled nanotubes from arc-discharge soot by high-resolution electron microscopy, sparking worldwide research. In 1993 Iijima and, independently, Bethune at IBM reported single-walled nanotubes.

制备方法有电弧放电、激光烧蚀和化学气相沉积（以 Fe、Co、Ni 纳米颗粒催化烃类分解，适合大规模生产）。碳纳米管用作锂离子电池导电剂（目前最大用途）、复合材料增强体、透明导电膜、场发射电子源和纳米电子器件；也有研究将其用于传感器和药物递送。长而细的多壁碳纳米管可能具有类似石棉的健康风险。

They are made by arc discharge, laser ablation and chemical vapour deposition, in which Fe, Co or Ni nanoparticles catalyse hydrocarbon decomposition, the route suited to large-scale production. Nanotubes serve as conductive additives in lithium-ion batteries (the largest use today), reinforcement in composites, transparent conductive films, field-emission electron sources and nanoelectronic devices, and are studied for sensors and drug delivery. Long, thin multi-walled tubes may pose asbestos-like health risks.