Structural Consequences of Duplicitous Chemical Relation of Cobalt and Fullerene in Mixture

Abstract

The factors driving the structure organization in the Co-C₆₀ films fabricated by simultaneous deposition were analyzed. It is shown that phase separation is the major factor yielding the nanocomposite (NC) structure in the co-deposited film (fcc-Co nanocrystals immersed into C₆₀-based matrix). The phase separation is accompanied by accumulation of compressive stress in the film mixture. The metal–fullerene chemical bonding is the next important factor responsible for creation of the –Co-C₆₀- polymer in the NC matrix. Thermal treatment can significantly influence the structure organization through enhancement of the main factors (phase separation or chemical bonding) that yields the remarkable structural effects. In particular, annealing at the elevated temperatures (T_a  = 300–500°C) induces the regular carbon structure transformations in the NC matrix followed by creation of carbon nanotubes or graphitic-like shells (depending on T_a ). The C-structure transformation is controlled by catalytic effect of Co atoms retaining in the NC matrix.

Keywords:

• Fullerene
• cobalt
• chemical bonding
• nanostructure
• self-organization

Acknowledgments

Financial support from the Grant Agency of the Academy of Science of the Czech Republic (KAN400480701) and from the Grant Agency of the Czech Republic (grants No. 106/09/1264 and No. P178-11-1856) is highly acknowledged.