Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 46: Nanomaterials I

MM 46.1: Talk

Thursday, March 29, 2012, 10:15–10:30, H 1029

SiC formation in carbon nanotubes grown from permalloy catalyst particles — •Anja Kießling¹, Darius Pohl¹, Christine Täschner¹, Rolf Erni², Mark Hermann Rümmeli¹, Ludwig Schultz¹, and Bernd Rellinghaus¹ — ¹IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany — ²Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Carbon nanotubes (CNT) were grown from Ni₈₀Fe₂₀ ("permalloy") catalyst particles on Si substrates using plasma-enhanced chemical vapour deposition (PE-CVD). The as-produced CNT were characterized by means of aberration-corrected high resolution transmission electron microscopy (using a FEI TITAN³ 80-300 microscope operated at 80kV). The as-grown CNT exhibit a clear contrast difference between the particle, the concentric graphene layers of the CNT and their cores. Electron Energy Loss (EEL) spectra reveal the core to be SiC from the occurrence of a Si-L absorption edge at around ΔE=100eV followed by a broad double-peak. Furthermore the CNT are found to be covered by a SiO₂ layer. The SiC core is expected to form during CNT growth as well as a Si film around the CNT due to the presence of Si in gas phase. This then oxidizes during exposure to ambient air. In summary, the CNT exhibit a complex core-shell structure consisting of a SiC core, a shell of concentric graphene layers and an amorphous SiO₂ overcoat.