Electron holography of single-crystal iron nanorods encapsulated in carbon nanotubes

Abstract

α - Fe nanorods encapsulated in multiwall carbon nanotubes (CNTs) were characterized by x-ray diffraction (XRD), high resolution electron microscopy (HREM), and electron holography. HREM observations revealed that the α-Fe nanoparticles were single crystals with a preferential growth direction of ⟨200⟩α-Fe oriented along CNTs. Phase distributions of an α-Fe nanorod were measured by electron holography and the remanent state was retrieved by a three-dimensional morphological model and an algorithm with the consideration of irregular nanoparticle shape. It was found that the saturated magnetization of the α-Fe nanorod with a CNT outer shell was very close to that of bulk pure α-Fe, suggesting that the core-shell nanostructure effectively prevented the surface oxidation that had been found to significantly degrade the magnetic properties of nanostructured α-Fe.