包覆纳米镍粒子的碳纳米管磁性研究(英文)

MAGNETIC PROPERTIES OF CARBON NANOTUBES ENCAPSULATING NANOSIZED NICKEL PARTICLES

通过溶胶 -凝胶超临界干燥技术制备出NiO SiO2 比为 1.2的二元气凝胶纳米催化剂 ,并以气凝胶为催化剂通过化学气相热解法合成了碳纳米管 ;碳纳米管的合成是在石英管式炉中完成。将催化剂置于石英舟中 ,在流动氮气中将管式炉加热至所需的温度 ,然后通入甲烷、氢气混合气体 ,热解反应 30min～ 6 0min后形成碳纳米管。反应结束后 ,生成的碳纳米管在氮气氛中冷却至室温。采用XRD、SEM、TEM、HRTEM、Raman分析手段对制得的碳纳米管进行了表征 ,并测定其磁化系数。结果表明 :裂解产物主要由碳纳米管和纳米镍粒子组成 ,且纳米镍粒子包覆于碳纳米管的顶端。这种包覆纳米镍粒子的碳纳米管的比饱和磁化强度和矫顽力分别为 0 .6 6A·m2 ·kg- 1 和2 0 15 7A·m- 1 。

Multi walled carbon nanotubes were synthesized by the catalytic chemical vapor decomposition method, and a binary aerogel with a 1.20∶1 nickel silica weight ratio was used as catalyst, which was prepared by the sol gel supercritical fluid drying method. The synthesis of carbon nanotubes was conducted in a quartz tube furnace. The catalysts in the quartz boat were heat treated to the required temperature under nitrogen atmosphere and reduced by flowing hydrogen for 30?min. Then the gas mixture of hydrogen and methane was introduced into the furnace and pyrolyzed for 30?min～60?min. Finally, the product obtained was cooled to room temperature under a nitrogen atmosphere. The samples were characterized by XRD, SEM, TEM, HRTEM, Raman spectra and susceptibility tests. The results showed that the pyrolytic product was composed of multi walled carbon nanotubes and nanosized nickel particles, which were encapsulated at the tip of the carbon nanotubes. Magnetic analysis showed that the carbon nanotubes encapsulating nickel had a specific saturation magnetization of 0.66?A·m 2·kg -1 and a coercivity of 20?157?A·m -1 .