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Electronic structure of layered MB[sub 2]C rare-earth borocarbide compounds

Journal Article · · Journal of the American Chemical Society; (United States)
DOI:https://doi.org/10.1021/ja00080a029· OSTI ID:5182175
; ; ;  [1];  [2];  [3]
  1. Universite de Rennes I (France)
  2. Institut National des Sciences Appliquees, Rennes (France)
  3. Universitaet Wien, Vienna (Austria)
The electronic structure and bonding properties of the layered borocarbide compounds with the ThB[sub 2]C, [alpha]-UB[sub 2]C, and YB[sub 2]C structures are analyzed and compared by means of extended Huckel tight-binding calculations. These materials contain alternatively metallic and boron-carbon sheets. The results show that an ionic picture between the metallic and the boron-carbon sublattices is a good starting point to explain the arrangement observed in the different nonmetal networks. Thus, a formal charge of 4- per B[sub 2]C unit accounts for the structure of the B-C net in ThB[sub 2]C and [alpha]-UB[sub 2]C, whereas a formal charge of 3- must be attributed to the one in YB[sub 2]C. An alternative B[sub 2]C two-dimensional arrangement is proposed for the charge of 4- per B[sub 2]C. The semimetallic nature observed for all the anionic two-dimensional boron-carbon layers is discussed. In the three-dimensional materials, the metal-nonmetal bonding occurs primarily through electron donation from the anionic sublattice toward the metallic elements. Metallic behavior is expected for all the materials. 37 refs., 14 figs., 3 tabs.
OSTI ID:
5182175
Journal Information:
Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:1; ISSN JACSAT; ISSN 0002-7863
Country of Publication:
United States
Language:
English