中文摘要：

采用溶胶-凝胶结合氢气还原方法制备了Ni纳米颗粒,并用这种Ni纳米颗粒作为催化剂,通过催化裂解乙炔的方法在425℃制备了螺旋度较高且呈对称生长的螺旋碳纳米管。结果表明,本方法简单、成本低、环境友好,可大量制备高纯度螺旋碳纳米管。场发射扫描电镜（FE-SEM）及高分辨透射电镜（HR-TEM）图片表明,通常情况下两根旋向相反的螺旋碳纳米管生长在一个催化剂颗粒上,且这种纳米螺旋呈空心管状。X射线衍射及拉曼光谱分析表明,所得样品成分为有缺陷的石墨结构和镍多晶,未发现其他杂相。此外,对样品的磁性及微波吸收性能进行了研究。

英文摘要：

The Ni nano-particles were generated by means of a sol-gel combined hydrogen reduction method.The helical carbon nanotubes（HCNTs） with high helicity and symmetric structure were synthesized in acetylene pyrolysis at 425 ℃ using the Ni nano-particles as the catalyst.The results show that this method is simple and environmentally friendly with low-cost,and is an ideal candidate for the mass production of HCNTs with high purity.The field-emission scanning electron microscope（FE-SEM） and high-resolution transmission electron microscope（HR-TEM） images show that there are often two nanotubes with the hollow tubular structure and opposite rotating directions in one catalyst nanoparticle.The XRD and Raman results reveal that the composites of the as-prepared sample are graphite with defect and polycrystalline Ni without impurity phase.Moreover,the magnetism and microwave absorption properties of the as-prepared sample were investigated.