X-ray Absorption and Magnetic Circular Dichroism in CVD Grown Carbon Nanotubes.

Stefano Bellucci,Mauro Giorcelli,Alberto Tagliaferro,Antonino Cataldo,Federico Micciulla

doi:10.3390/ma12071073

Abstract

Nowadays, a deep knowledge of procedures of synthesis of nanostructured materials plays an important role in achieving nano-materials with accurate and wanted properties and performances. Carbon-based nanostructured materials continue to attract a huge amount of research efforts, because of their wide-ranging properties. Using X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy in the soft X-ray regime, by the synchrotron radiation, we studied the L3,2 absorption edges of iron (Fe) nanoparticles, when they are embedded in oriented Multi Wall Carbon Nanotube (MWCNTs) layers grown by thermal Chemical Vapor Deposition (CVD) technique catalyzed by this transition metal. This could allow us to understand the valence state and role of catalysts and thus their electronic and magnetic structures. It is important to note that the control of the size of these tethered nanoparticles is of primary importance for the purpose of tailoring the physical and chemical properties of these hierarchical materials. The MWCNTs samples used in XAS and XMCD measurements were synthesized by the CVD technique. The actual measurements were carried out by the group NEXT of the INFN- LNF with the logistic experimental support of the INFM-CNR and the Synchrotron Elettra Trieste.

Highlights

The study of carbon nanotubes (CNTs) [1] has opened up research in many disciplines, as these materials possess many unique physical properties with novel applications in various fields [2]
Contrast, when the scan with linear polarization and oblique incidence was performed on the smooth when the scan with linear polarization and oblique incidence was performed on the smooth surface of surface of the MWCNT forest, quite surprisingly, the peaks showed up with an inversion of their intensity with respect to the decreasing background
MWCNTs layers grown by the thermal Chemical Vapor Deposition (CVD) technique catalyzed by this transition metal, were carried

Summary

Introduction

The study of carbon nanotubes (CNTs) [1] has opened up research in many disciplines, as these materials possess many unique physical properties with novel applications in various fields [2]. It has been shown that these new materials can be tailored to have many interesting properties: Metallic, semiconducting, and magnetic. Among the number of methods to synthesize CNTs, the chemical vapor deposition method is used to prepare selectively single, double, and multi-walled CNTs [3]. This method uses mainly 3d transition metals (TM) Fe, Ni, and Co as catalysts, which come into contact with tube walls and significantly influence the transport, magnetic, and electronic properties. Synchrotron radiation source-based studies, such as high energy electron spectroscopies are likely to provide a better insight in understanding the magnetic and electronic structure of these materials. The X-ray absorption and magnetic circular dichroism in the soft X-ray regime attract considerable interest, owing to the possibility of extracting microscopic information about spin and orbital momenta with element specificity [4]

Methods

Results

Conclusion