Creation of carbon onions and coils at low temperature in near-critical benzene irradiated with an ultraviolet laser
Creation of carbon onions and coils at low temperature in near-critical benzene irradiated with an ultraviolet laser
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DOI：
10.1088/0957-4484/18/41/415604
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发表时间：
2007-10-17
期刊：
影响因子：
3.5
通讯作者：
Maekawa, Toru
中科院分区：
文献类型：
--
作者：
Fukuda, Takahiro;Watabe, Nami;Maekawa, Toru
气液共存曲线终止于发生二级相变的临界点。当流体系统接近其临界点时，比热和可压缩性大大增加。结果，热扩散被抑制，温度、压力和密度的扰动以声波的形式传播。在本文中，我们用波长为266 nm的激光照射近临界苯，能量流分别为1.3和3.9 mW mm(-2)，结果表明苯被解离，并产生了各种碳纳米/微结构，如碳洋葱和线圈。碳洋葱是在亚临界(200摄氏度)和超临界(290摄氏度)苯中产生的，而碳线圈是在超临界苯中用3.9毫瓦毫米(-2)激光照射组成的合金催化剂上产生的。该方法的操作温度远低于传统的碳结构合成方法，并且在超临界苯中生成大量的碳结构，如碳洋葱和碳线圈。
Gas -liquid coexistence curves terminate at their critical points, where second-order phase transitions occur. The specific heat and compressibility increase greatly as the fluid systems approach their critical points. As a result, thermal diffusion is suppressed and the perturbations of the temperature, pressure and density propagate as acoustic waves. In this paper, we irradiate near-critical benzene with a laser beam of 266 nm in wavelength, the energy flux of which is 1.3 and 3.9 mWmm(-2), and show that benzene is dissociated and various carbon nano/ microstructures such as carbon onions and coils are created. Carbon onions are produced in both subcritical ( 200 degrees C) and supercritical ( 290 degrees C) benzene, whereas carbon coils are produced on an alloy catalyst composed of ( Fe: Cr: Ni = 74: 18: 8) in supercritical benzene irradiated with a laser beam of 3.9 mWmm(-2). The operational temperature of the present method is much lower than that used in conventional carbon structure synthesizing methods and a large number of carbon structures, such as carbon onions and coils, are produced in supercritical benzene.