碳微线圈的气-液-固-固生长机理

碳微线圈具有类似DNA的双螺旋结构, 通常以镍为催化剂, 噻吩为助剂采用CVD法制备, 但是对于它的生长机理人们仍不十分清楚. 本文发现构成碳微线圈的碳纤维由三条亚纤维组成, 提出了碳微线圈的气-液-固-固生长机理, 并以此对实验事实做出合理解释.

Vapor-Liquid-Solid-Solid Growth Mechanism of Carbon Micro-coils

Carbon micro-coils, which have double helix structure, are generally prepared by catalytic chemical vapor deposition of acetylene, using Ni as the catalyst. It is well known that the coils are formed because of the catalytic anisotropy, however the growth process of carbon micro-coils is still unclear. In this paper, it is reported that the fiber constructing the carbon micro-coil is composed of three sub-fibers. Referring to this experimental finding and known facts from the phase diagrams, a vapor-liquid-solid-solid growth mechanism of carbon micro-coils is pproposed. In this mechanism every catalyst particle can be divided into two parts, one is liquid while the other is solid. The schematic growth process of the carbon micro-coil is shown. Carbon atoms firstly permeate into the liquid portion from gas, then disperse into the solid portion, and finally deposit from six crystallographic facets of the catalyst to form the carbon micro-coil.