Preparation of Carbon Onions by Ion Bombardment

In attempts to generate diamond films by the implantation of carbon ions into copper substrates, T. Cabioc h and co-workers made a remarkable discovery instead of the expected diamond crystallites, they found large, spherical carbon particles with graphitic structure. In further experiments, they could demonstrate the technique to be applicable to other substrates. 

Suitable substrates include silver and copper besides further metals like gold, tin, or lead. An essential feature of all relevant materials is a poor solubiUty of carbon in them. Consequently, segregation occurs upon carbon atoms penetrating 

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