Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

Abstract

We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (NiMWNTs) with an average diameter of 115 nm and variable length of 400 nm -1 µm. The NiMWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H 2 /C 2 H 2 at a temperature of 700 o C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.2

Synthesis of Magnetic Composite of Iron Compounds/Carbon Nanotubes in Chemical Vapor Deposition

“…However, the com-CNT growth was more straightly aligned. The encased metal catalyst inside the produced CNT was also observed in previously published pioneering works [31][32][33][34]44]. The com-CNT growth proceeds according to a sequence of steps: precursor diffusion in the chamber, precursor adsorption to the catalyst surface, the chemical reaction between the precursor and the catalyst, the formation of the resultant product with predominant carbon species, the desorption of the non-carbon product, the condensation of the carbon species in the bulk stream on the catalyst, and the arrangement of new chemical carbon bonds in hexagonal and/or pentagonal structures to form CNT [45].…”

“…Therefore, synthesizing magnetic CNT in one step will be more efficient. A single step of magnetic CNT synthesis may possibly be directly by CVD, as reported in several articles [32][33][34]. However, in this single step, the high purity of hydrocarbon gases (e.g., methane, acetylene, propane, etc.)…”

Graphite Coating of Iron Nanowires for Nanorobotic Applications: Synthesis, Characterization and Magnetic Wireless Manipulation

“…Preparation of Anodic Aluminum Oxide Templates : Anodic aluminum oxide (AAO) templates with a uniform and parallel porous structure were prepared by anodizing an e‐beam evaporated layer of Al (1.5–2 μm thick) on Si substrate with Ti and Au‐seed layers as reported previously 5, 6. A current controlled single‐step anodization was carried out in 0.3 M oxalic acid.…”

“…Materials science, pharmacy, engineering and other disciplines have contributed synergistically to the development of nanoscale TDD platforms in several aspects such as nanomaterials synthesis, nanofabrication, motion control, functionalization, drug dosing and triggering methods. A promising approach involves using magnetic nanoagents that can be wirelessly maneuvered by applying external magnetic fields 2–7. This drug targeting strategy could reach confined spaces in the human body to locally deliver therapeutic drugs or molecular vectors.…”

“…We demonstrate that Fe NWs are conformally coated by highly crystalline continuous graphitic shells under optimized conditions. The method uses anodic aluminum oxide (AAO) templates on silicon in which Fe NWs are produced by pulsed electrodeposition (PED) (see details on fabrication in the Supporting Information, S1 and S2) 5, 6. Subsequently, the Fe NWs kept in the template are coated with graphite by chemical vapor deposition (CVD).…”