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We report the observation of an unusual self-peeling effect which allows the synthesis of free standing vertically aligned carbon nanotube films filled with large quantities of Fe3C and small quantities of γ-Fe crystals. We demonstrate that this effect depends on the interplay of three main factors: (1) the physical interactions between the chosen substrate surface and grown carbon nanotubes (CNTs), which is fixed by the composition of the used substrate (111 SiO2/Si or quartz), (2) the CNT-CNT Van der Waals interactions, and (3) the differential thermal contraction between the grown CNT film and the used substrate, which is fixed by the cooling rate differences between the grown film and the used quartz or Si/SiO2 substrates. The width and stability of these films are then further increased to cm-scale by addition of small quantities of toluene to the ferrocene precursor. [ABSTRACT FROM AUTHOR]

A major challenge in the growth of ferromagnetically-filled‑carbon-foam (FFCFM) materials is the achievement of a carbon-monolayer configuration. Up to now, the fabrication of this type of materials has been indeed strongly limited by the difficulties in controlling the characteristics (i.e. the number of carbon layers) of their carbon onions (CNOs) precursors. In this work we addressed this problem and we investigated the formation-mechanism of such monolayer FFCFM using novel bilayer CNOs-like capsules filled with Fe 3 Pd and FePd 3 crystals as precursor-materials. These novel bilayer CNOs-capsules were obtained by pyrolysis of great excess of ferrocene and dichlorocyclooctadiene palladium mixtures. The modification of the surface characteristics of these capsules and the conversion-mechanism into monolayer FFCFM were investigated through two main methods, namely i) high temperature post-synthesis annealing and ii) post-synthesis high temperature Raman-laser-irradiation. The presence of a monolayer configuration in the FFCFM was firstly probed by the use of multiple techniques such as SEM, TEM, XRD, XPS and Raman spectroscopy and confirmed further by HRTEM/STEM. This novel method of production opens new avenues toward the control of the surface-characteristics of FFCFM-materials for applications involving mass-transport-phenomena, low-dimensional-materials-synthesis and others. In addition the bilayer/monolayer CNOs used as FFCFM precursor may find additional applications in shape-memory-devices. [ABSTRACT FROM AUTHOR]