The local environment of Co in B\u3csub\u3e5\u3c/sub\u3eCH\u3csub\u3e\u3ci\u3ex\u3c/i\u3e\u3c/sub\u3e

Cobalt-doped boron carbides produced by simultaneous plasma-enhanced chemical vapor deposition of carborane and cobaltocene are investigated. Cobalt does not dope plasma-enhanced chemical vapor deposition grown boron carbides as a random fragment of the cobaltocene source gas. The Co atoms are fivefold boron coordinated (R=2.1 Å) and chemically bonded to the icosahedral cages of B10CHx or B9C2Hy. Pairwise Co doping occurs with the cobalt atoms favoring sites about 5.3 Å apart. The cobalt strongly hybridizes with the molecular orbitals of the icosahedral cage, and the states in the region of the band gap probably have a strong cobalt weight