Protective nature of the outer graphitic cages against oxidation of the inner LaC crystallites in nanocapsules

Yamamoto, Kazunori; Wakahara, Takatsugu*; Akasaka, Takeshi*

There has been great interest in the incorporation of foreign materials into fullerene-like carbon structures (C, nanotubes, nanocapsules). Nanocapsules filled with LaC crystallites were discovered in carbonaceous cathode deposits grown by arc discharge under an inert gas atmosphere in 1993. Although rare-earth carbides are hygroscopic and readily hydrolyze in moist air, the carbides in the capsules did not degrade even after a decade of exposure. Moreover, empty nanocapsules and nanotubes are more resistant to oxidation than other forms of carbon (such as diamond, soot, graphite, and C). Therefore higher oxidation resistance is also expected for the filled nanocapsules. In this study protective nature of the outer graphitic cages of stuffed nanocapsules was demonstrated.