Cobalt-doped carbon nanotubes: Preparation, texture, and magnetic properties

Abstract

The nested carbon nanotubes discovered by Ijima and co-workers as a by-product of fullerene production extended the dimension and geometries of fullerenes into the domain of nanoparticles. These nanotubes are fiberlike structures consisting of concentric graphite sheets nested along the axis extending as long as several micrometers, and diameters of these nanotubes are limited to less than 100 nm. In this paper we report preparation, structural and magnetic properties of cobalt-doped carbon nanotubes. We observed a tubular structure made of coaxial graphite sheets. The inside, of these carbon nanotubes, was filled with cobalt particles. The magnetic properties of the Co-doped nanotubes were measured using a SQUID magnetometer. The undoped (pure) carbon nanotubes exhibit diamagnetic behavior. The Co-doped nanotubes exhibit superparamagnetic behavior with saturation of magnetization at about 0.5 T and coercive field of 750 G.

Highly stable Fe–Ni alloy nanoparticles encapsulated in carbon nanotubes: Synthesis, structure and magnetic properties

“…When the Ni content is around 50 wt%, the amount of positive-spin electrons reaches its maximum, and magnetic moments start to decline. In addition there is an interaction between the ferromagnetism of FeNi alloy and diamagnetism of carbon [30], making the magnetic properties of FeNi-CNTs composites complicated.…”

Carbon Nanotubes: Synthesis, Properties, and Applications

“…340 The arc process is likewise used to make CNTs filled with Co that displays ferromagnetic behavior instead of the usual diamagnetic behavior of pure CNTs. 341 It can also partially or completely fill SWNTs with Ag. 342 Nanocrystals of Co or Au can also be covered with nano-onions in arc processing followed by electron irradiation.…”

Vertically aligned N-doped carbon nanotubes by spray pyrolysis of turpentine oil and pyridine derivative with dissolved ferrocene

“…The deliberate introduction of defects and impurities (dopants) into the carbon nanotubes could offer a possible route to change and tune its electronic properties in a well defined way. Heteroatoms (boron, nitrogen, cobalt, potassium, silicon, phosphorous, oxygen) doping into graphitic carbon lattices effect various properties of sp 2 carbon material [3][4][5][6][7][8][9]. The advantage of such nanotubes is that their electronic properties are primarily determined by composition and are thus relatively easy to control.…”