碳纳米管在0.5～6GHz低频波段的介电常数和磁导率研究

Study on Permittivity and Permeability of Carbon Nanotubes in the Low-frequency Band from 0.5 to 6 GHz

采用化学气相沉积法制备多壁碳纳米管,运用高温氧化、浓盐酸处理和混酸回流工艺对其进行纯化;采用FTIR、TEM和EDS比较各工艺对碳管表面结构的影响程度,运用同轴波导法测定碳管在0.5～6GHz低频波段内的介电常数和磁导率数值。结果表明：碳管中无定形碳的存在,有效地提高了碳管的介电损耗;长时间的浓盐酸或混酸处理,会改变碳管的极化特性,对碳管在低频波段的介电常数构成明显的影响。

Carbon Nano Tubes （CNTs） were prepared by the thermal CVD method, and then purified by hightemperature oxidation, concentrated HCI and H2SO4/ HNO3 mixture. Then these CNTs were analyzed by FTIR, TEM and EDS, to study the change of external structure. The complex permittivity and permeability were measured from 0.5 to 6 GHz by the coaxial-waveguide method. The results show that existence of amorphous carbon can improve dielectric loss. It is also found that concentrated HCI or H2SO4/ HNO3 treatment for long times will change polarization performance and external structure of CNTs, affect the permittivity of CNTs in low-fi-equency band finally.