Effects Of Element-Doping On Electromagnetism Property Of Carbon Nanotubes

Since the discovery of Carbon Nanotubes (CNTs) in 1991, its unique structure and excellent mechanical, electrical, magnetical performance have been focused by many researchers. Doping technique means adding a little matter (or element) into pristine sample with keeping the sample's pristine main component, that's for changing the physical and chemical performance of the sample. Generally speaking, CNTs' crystal structure and electronic structure may have been changed after being doped with other matter (for example, Boron), and thus resulting the changing of the sample physical property.In this thesis, we added boron powder and magnesium powder into CNTs with keeping the CNTs' hollow nanotubes structure, in order to controll and change CNTs' magnetics performance.1. Boron carbide nanotubes (nano-fibers) were prepared by boron powder and CNTs at high temperature in a quartz tube in vacuumed air. The morphology, microstructure, component and magnetic property of the samples were characterized by Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and MPMS controller. The results showed that the boron-doping CNTs have great different morphology and magnetic property from that of the pristine CNTs.2. We used Boron Carbon nanotubes as matrix, added magnesium powder into the marix at high temperature in a quartz tube in vacuumed air. The morphology, component and magnetic property of the obtained samples were characterized by Transmission electron microscopy, Scanning electron microscopy, X-ray diffraction and MPMS controller. The results showed that the samples of doping magnesium appeared perfect diamagnetism, and its transition temperature is about 30K.3. The effect of CNTs' content on doping samples' perfect diamagnetism transition temperature was studied. The results showed that the samples' perfect diamagnetism transition temperature had decreased with the increasing of the CNTs' content.