Exploration of carbon nanomaterials and their growth dynamics by the control of high-temprature state

在高压惰性气体中(高达0.9兆帕)激光气化碳材料可以得到新型的纳米碳。限制激光蒸发碳并保持其高温会导致各种纳米碳的生长。我们通过热石墨化的方法制备了100-1000 nm的多面体石墨(PG)颗粒，产率高达90%。我们还成功地产生了含氮或氟的PG。在激光汽化过程中，在充入0.9 Mpa的N_2或CF_4气体的小室中，将连续波的激光聚焦到石墨靶上。3个或1个at的法团。X-射线光电子能谱分析表明，PG中N或F原子的含量为%。我们还发现，1 at.%的硅可以促进PG和气球状碳颗粒的形成。10种元素的金属与碳一起在Ar气氛中被激光汽化2 S。得到的产物是单壁碳纳米角(SWNH)颗粒与其他纳米碳材料的杂化。通过控制Ar气压和Fe、Co、Ni、Cu、Ag激光照射石墨靶中的元素含量，我们能够制备出含金属或碳化物纳米胶囊(CNCS)的SWNH颗粒，产率约为70%。在相同的工艺条件下，B、Al、Si、Y和Gd没有形成杂化的SWNH颗粒，而形成了多壁碳纳米管(MWNTs)、碳化物线等。激光蒸发金属也可用于生产纳米碳复合材料。通过激光蒸发铜和钛对多壁碳纳米管进行了改性。

Laser vaporization of carbon materials in high pressure inert gas (up to 0.9 MPa) can produce novel nanocarbon. Confining laser-vaporized carbon and maintaining its high temperature result in the growth of various nanocarbon. We have conducted the fabrication of polyhedral graphite (PG) particles of 100-1000 nm with a high yield (>90%) through thermal graphitization. We have also succeeded in generating nitrogen or fluorine containing PG. For laser vaporization, the laser beam from a continuous wave Nd:YAG laser was focused onto a graphite target in a chamber filled with N_2 or CF_4 gas of 0.9 MPa. Incorporations of 3 or 1 at. % of N or F atoms in PG were found from x-ray photoelectron spectroscopy. We also found the enhanced formation of PG and balloon-like carbon particles achieved by the coexistence of 1 at.% silicon.Metals of ten elements were laser-vaporized with carbon for 2 s into an Ar gas atmosphere. The products obtained were hybridized single-wall carbon nanohorn (SWNH) particles and other nanocarbon materials. Controlling the Ar gas pressure and the element content in a laser-irradiation graphite target for Fe, Co, Ni, Cu, and Ag enabled us to fabricate SWNH particles including metal- or carbide-containing carbon nanocapsules (CNCs) with the high yield of approximately 70%. Under the same processing conditions, B, Al, Si, Y, and Gd did not form hybridized SWNH particles and formed multi-wall carbon nanotubes (MWNTs), carbide wires, etc. We investigated the metal-dependent and high-yield growth of the hybrid structure of the SWNH particle and the CNC. Laser vaporization of metal was also useful to produce nanocarbon composites. MWNTs were modified by laser vaporization of Cu and Ti.