Fabrication and microwave absorption of carbon nanotubes CoFe 2O4 spinel nanocomposite

A large-scale carbon nanotube CoFe2 O4 (CNTs CoFe2 O4) spinel nanocomposite has been fabricated by a chemical vapor deposition method using CoFe2 O4 nanoparticles as catalysts. A uniform mixture of CNTs and CoFe2 O4 nanoparticles was obtained simultaneously. The structure and chemical composition of the product were investigated using various techniques, such as x-ray diffraction, high-resolution transmission electron microscopy, and electron energy loss spectroscopy. It was found that the particles functionalized on CNTs were cubic phase CoFe2 O4. Microwave absorption of the CNT CoFe2 O4 nanocomposites at 2-18 GHz is evidently enhanced, as compared with that of both pure CNTs and CoFe2 O4 nanoparticles. The enhancement mechanism is discussed based on magnetization hysteresis loop measurement and electromagnetic theory. © 2006 American Institute of Physics.