Magnetic characterization of web-like carbon nanotubes catalyzed by Fe 2O3 via pulsed Laser Ablation Deposition (PLAD) technique

Web-like carbon nanotubes were synthesized via Laser Ablation Deposition (PLAD) in a T-shape stainless steel chamber. An Nd-YAG laser with a 532 nm wavelength was used to irradiate a target of graphite and a catalyst, with a 57 ns pulsed width. Fe2O3 was used as a catalyst to produce a reactive graphite target. The vacuum level was kept at 5 Torr with argon gas flowing from the bottom of the chamber. The plume that was deposited on a glass substrate was then characterized using a Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) analysis, a Transmission Electron Microscope (TEM), and a Vibrating Sample Magnetometer (VSM). Web-like CNT structures were deposited on the glass substrate. These web-like structures were randomly aligned with sizes of 99 nm to 234 nm. TEM images confirmed that these web-like structures were CNTs. VSM results showed that the encapsulation of the Fe 2O3 catalyst had influenced the magnetic properties of the CNTs. The magnetic property of CNTs was increased with the increasing amount of the Fe2O3 catalyst filling the CNTs. We assert that the starting catalyst material was transformed from hematite to magnetite via maghemite by a structural change under a reduced oxygen atmosphere during the laser ablation. © 2011 World Scientific Publishing Company.