Synthesis and properties of magnetically functionalized carbon nanotubes

Abstract

This paper reports on the results of a complex investigation of the crystal structure, the composition, and the specific magnetization of magnetically functionalized multiwall carbon nanotubes. The carbon nanotubes are synthesized by the high-temperature pyrolysis of liquid hydrocarbon p-xylene C8H10 in a mixture with a volatile catalyst, namely, ferrocene Fe(C5H5)2, on the surface of silicon substrates in a quartz reactor. Under the synthesis conditions used in the experiment, arrays of vertically aligned nanotubes are formed on the silicon substrates and reactor walls. It is established that carbon nanotubes of both types exhibit identical properties and represent a complex nanocomposite, C-Fe3C-Fe5C2-Fe. An analysis of the temperature dependences of the specific magnetization σ = f(T) demonstrates that, in the temperature range 78 K ≤ T ≤ 1060 K, the magnetic properties of the nanotubes under investigation are governed by the properties of iron carbides (in the form of Fe3C and Fe5C2) and iron. It is revealed that the synthesized carbon nanotubes possess reversible magnetic properties in the temperature range 78 K ≤ T ≤ 720 K.