Solid State NMR of 11B and 13C in Boron Carbide, B12C3 and 11B Enriched B12C3

Abstract

Abstract 11B- and 13C-solid state NMR of boron carbide with different isotope ratios, B4C(11B/10B = 80.42/19.58; natural abundance isotope) and 11B4C(11B/10B = 99.5/0.5; 11B enriched sample), has been investigated. The linewidth of the icosahedral B (6h1and 6h2) in 11B-static NMR signal in 11B4C was greater in 11B4C than in B4C, which indicates that the B–B dipole–dipole interaction is the main mechanism for the broadening of the 11B-static NMR signal. The quadrupole coupling constant calculated from the signal position of (±1/2 ↔ ±3/2) transition was about 0.1 MHz. 11B-MAS spectra revealed the presence of at least two additional B sites (37 ppm and near −60 ppm) besides the icosahedral B sites (−6 ppm).