Single-Crystalline Permalloy Nanowires in Carbon Nanotubes: Enhanced Encapsulation and Magnetization

Abstract

We report the use of dichlorobenzene as a carbon source to produce carbon nanotubes with thinner walls and a relatively large cavity, boosting the efficiency of metal encapsulation inside nanotubes. As an example, we show that Permalloy (FeNi) was encapsulated in nanotubes in the form of long nanowires and reached more than 30 wt % of the final product. These Permalloy nanowires are single crystalline, with a typical length of several micrometers and an aspect ratio of >100, and sheathed by several graphene layers. Such Permalloy nanowires show much-enhanced magnetization and microwave absorption properties, compared with Fe or FeNi nanowires produced by the source materials without adding Cl. The improved magnetic properties are due to a more efficient in situ encapsulation of Permalloy and a lesser number of nanotube walls coated on the surface of nanowires.