Boron carbide, B(13-x)C(2-y) (x = 0.12, y = 0.01).

ABSTRACT: Boron carbide phases exist over a widely varying compos-itional range B(12+x)C(3-x) (0.06 < x < 1.7). One idealized structure corresponds to the B(13)C(2) composition (space group R-3m) and contains one icosa-hedral B(12) unit and one linear C-B-C chain. The B(12) units are composed of crystallographically distinct B atoms B(P) (polar, B1) and B(Eq) (equatorial, B2). Boron icosa-hedra are inter-connected by C atoms via their B(Eq) atoms, forming layers parallel to (001), while the B(12) units of the adjacent layers are linked through inter-icosa-hedral B(P)-B(P) bonds. The unique B atom (B(C)) connects the two C atoms of adjacent layers, forming a C-B-C chain along [001]. Depending on the carbon concentration, the carbon and B(P) sites exhibit mixed B/C occupancies to varying degrees; besi

SUBMITTER: Sologub O 

PROVIDER: S-EPMC3414096 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature