| 碳纳米管内分立的纳米铁粒子的热氧化性能研究(英文) |
| Thermal Oxidation Mechanism of Fe Nano-particles Encapsulated Separately in Carbon Nanotubes |
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| 摘要: 研究了纳米铁填充的碳纳米管基复合纤维在空气中的热氧化性能。结果表明：一般在室温即被氧化的铁(Fe)纳米粒子在170 ℃仍然具有良好的稳定性。这一方面是由于碳纳米管的保护作用所致，另一方面碳纳米管末端的Fe纳米粒子在室温下即迅速被氧化成反尖晶石型Fe3O4/γ-Fe2O3，170 ℃以下能有效阻止氧分子向碳纳米管内扩散。因此，170 ℃可以被看作氧分子扩散进入碳纳米管腔的极限温度。在170 ℃以下时，氧分子无法渗透Fe3O4 /γ-Fe2O3晶格在管腔中形成氧分子。当温度高于170 ℃时，氧分子渗透发生，管腔内的Fe纳米粒子由靠近管末端位置到内部逐渐被氧化。由于相对良好的热氧化稳定性，Fe填充碳纳米管基复合纤维的铁磁性将可以在更高温度范围内得以保持。 |
| 关键词: 热稳定性 碳“纳米试管” 反尖晶石结构 氧扩散 临界温度 |
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| Abstract: Thermal oxidation of Fe nano-particles in nanoscopic reactors of carbon nanotubes(CNTs) was investigated by treatment in air from room temperature to 800 ℃. It is found that encapsulated Fe nano-particles are thermally stable up to a relatively high temperature of 170 ℃ comparing to oxidization at room temperature of bare ones. Fe nano-particles in the tube end of CNTs is easily oxidized to form inverse spinel structure Fe3O4 /γ-Fe2O3 nano-particles, serving as barriers to prevent oxygen from diffusion into the inner hollow cavity of CNTs. It is suggested that 170 ℃ is the critical temperature(Tc) of oxygen diffusion through the barriers. At temperatures lower than 170 ℃, oxygen molecules can not diffuse through the lattice of Fe3O4 /γ-Fe2O3 nano-particles to form oxygen molecules in the cavity of CNTs, while at higher temperatures the penetration of oxygen occurs and Fe nano-particles from the tip to inner most in CNTs are gradually oxidized. The mechanism is different from the oxidation behavior and thermal stability of a CNT-encapsulated Fe nanowire, which is oxidized continuously once the oxidation occured by oxygen ions migrating through the lattice of iron oxides and combines with Fe atoms to complete the oxidation process. |
| Keywords: thermal stability carbon “test tube” inverse spinel structure oxygen diffusion the critical temperature |
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| 黄 钊,陈乾旺,刘业如.碳纳米管内分立的纳米铁粒子的热氧化性能研究(英文)[J].无机化学学报,2009,25(2):321-329. |
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