Regensburg 2013 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 45: Nanomaterials - Nanospheres & Fibres
MM 45.2: Vortrag
Mittwoch, 13. März 2013, 16:45–17:00, H26
C58 solid materials: mechanical properties vs thermal stability — Seyithan Ulas1, Sven Bundschuh2, Chris Eberl2, Henrik Hölscher3, •Artur Böttcher1, and Manfred Kappes1 — 1Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany — 2Institute of Advanced Materials and Material- and Biomechanics (IAM-WBM), KIT, Germany — 3Institute of Microstructuring Techniques, KIT, Germany
Non-IPR C58 cages as created by electron-impact induced fragmentation of IPR-C60 fullerenes have been exploited as building blocks of new materials grown by applying low energy cluster beam deposition. The material fabricated at room temperature appears to be an amorphous wide-band semiconductor, RT-C58. Nanoindentation as applied to measure elastic modulus E and hardness H reveals values higher than those found for IPR-C60 solids: E(RT)=14.1 GPa and H(RT)=1.23 GPa. This observation is rationalized in terms of the unique functionalization of C58 cages by non-IPR sites which are responsible for the formation of covalently stabilized C58 oligomers. Annealing the RT-C58 films up to 1100 K results in a new material, HT-C58, which exhibits considerably modified electronic and vibrational properties. Such annealing activates the mobility of the initially vdWaals-stabilized cages and consequently maximizes their coordination degree (densification and strengthening by covalent interlinking). The related molecular transformations raise the overall mechanical hardness of the material: H(HT)= 3.9 GPa, i.e. H(HT)=3 H(RT).