title: Microscopic insight into the bilateral formation of carbon spirals from a symmetric iron core.
abstract: Mirrored carbon-spirals have been produced from pressured ferrocene via the bilateral extrusion of the spiral pairs from an iron core. A parametric plot of the surface geometry displays the fractal growth of the conical helix made with the logarithmic spiral. Electron microscopy studies show the core is a crystalline cementite which grows and transforms its shape from spherical to biconical as it extrudes two spiralling carbon arms. In a cross section along the arms we observe graphitic flakes arranged in a herringbone structure, normal to which defects propagate. Local-wave-pattern analysis reveals nanoscale defect patterns of two-fold symmetry around the core. The data suggest that the bilateral growth originates from a globular cementite crystal with molten surfaces and the nano-defects shape emerging hexagonal carbon into a fractal structure. Understanding and knowledge obtained provide a basis for the controlled production of advanced carbon materials with designed geometries.
authors.affiliation: Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Wien, Austria. hidetsugu.shiozawa@univie.ac.at
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Shiozawa
authors.forename: Alicja
authors.initials: A
authors.lastname: Bachmatiuk
authors.forename: Andreas
authors.initials: A
authors.lastname: Stangl
authors.forename: David C
authors.initials: DC
authors.lastname: Cox
authors.forename: S Ravi P
authors.initials: SR
authors.lastname: Silva
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rümmeli
authors.forename: Thomas
authors.initials: T
authors.lastname: Pichler
mesh_terms: D005296:Ferrous Compounds / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D000075163:Metallocenes; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D005296:Ferrous Compounds; D000075163:Metallocenes; D037742:Nanotubes, Carbon; D006108:Graphite; C004998:ferrocene