Magnetic Nanostructures Grown on Vertically Aligned Carbon Nanotube Templates

Abstract

We describe the growth of magnetic nanostructures on carbon nanotube templates. The nanotubes were grown by microwave plasma enhanced chemical vapor deposition. The as-grown nanotubes were aligned reasonably well around the substrate normal directions. However, it was found that the nanotubes grown on magnetic catalysts tend to regroup into microumbrella-like structures under an external magnetic field due to the dipole interactions among the magnetic particles at the top tips of the nanotubes. To prevent the regrouping of nanotubes and also facilitate the study of magnetic properties of subsequently formed magnetic nanostructures, antiferromagnetic materials have been used for the formation of nanotubes. The hysteresis loops of the nanostructures have been measured using a vibrating sample magnetometer at both room and elevated temperatures. The shape of the hysteresis loops suggested that there exists a strong magnetostatic interaction in this system. Multiple steps have been observed in the coercivity versus temperature curves, which are attributed to the size-effect of the magnetic nanostructures.

The decoration of multi-walled carbon nanotubes with nickel oxide nanoparticles using chemical method

“…Because of their interesting dimensions and high surface areas, various inorganic nanoparticles, such as metals, metal oxides, and semiconducting nanoparticles, were coated on the surface of CNTs. Decoration of the surface of CNTs can get better the dispersity of CNTs in solvents [18] as well as promotion their optical, electric, and magnetic properties [7,19,25,26].…”

“…To date, many researchers have attempted to produce metal or metal oxide nanoparticles attaching on the external surface of CNTs or filling inside the CNTs [4,8,9,26,27]. Nickel oxide (NiO), as an important transition metal oxide, is a very promising material and has attracted increasing attention due to its extensive important applications as catalysis [20], electrode materials [21], gas sensor [10,17], and electrochemical films [11].…”

Polymer Nanocomposite Materials for Structural Applications

“…A single material with more than two functionalities such as improved mechanical properteis along with magnetic, electrical optical, and sensing capabilities. It is also know in the literature that the decoration of CNTs with metal or metal oxides can improve dispersion of CNTs in solvents (Oh-Kil et al, 2003;Chin et al, 2004;Oymak et al, 2004;Watts et al, 2002;Wu et al,2002) or reveal new optical, electric, manetic properties of CNTs (Lidström et al, 2001;Alexandre et al, 2000;Wiesbrock et al, 2004;Kerep et al, 2006). To address some of the multifunctionalities of a materials we have prepared the iron oxide nanoparticled coated on CNTs.…”

Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

“…For example, decorating can improve dispersion of CNTs in solvents or impart new optical, electric, magnetic properties [18][19][20]. Recently, decorating CNTs with different materials, such as magnetic nanoparticles [21][22][23], noble metals [24][25][26], polymers [27][28][29] and biomaterials [30,31] have been extensively reported.…”