The local environment of Co in B{sub 5}CH{sub x}

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 A) and chemically bonded to the icosahedral cages of B{sub 10}CH{sub x} or B{sub 9}C{sub 2}H{sub y}. Pairwise Co doping occurs with the cobalt atoms favoring sites about 5.3 A 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.