Atomic structure of icosahedral B4C boron carbide from a first principles analysis of NMR spectra -: art. no. 085506

Density functional theory is demonstrated to reproduce the C-13 and B-11 NMR chemical shifts of icosahedral boron carbides with sufficient accuracy to extract previously unresolved structural information from experimental NMR spectra. B4C can be viewed as an arrangement of 3-atom linear chains and 12-atom icosahedra. According to our results, all the chains have a CBC structure. Most of the icosahedra have a B11C structure with the C atom placed in a polar site, and a few percent have a B-12 structure or a B10C2 structure with the two C atoms placed in two antipodal polar sites.