CHARACTERIZATION OF BERYLLIUM-BORON-BEARING MATERIALS BY PARALLEL ELECTRON-ENERGY-LOSS SPECTROSCOPY (PEELS)

The stoichiometry of a set of commercial and laboratory-synthesized Be -B-bearing materials was determined by parallel electron energy-loss s pectroscopy (PEELS), The Be and B K edges are well separated in energy , allowing easy determination of the elemental ratios, PEELS analyses of materials with reported compositions of ''Be2B'' and ''Be2B3'' prov ided stoichiometries near Be2.8B and Be4B5, respectively, We confirmed an earlier report of Be-0.6(+/-(0.1)) B5.9(+/-0.7)C, a material with the alpha-rhombohedral B structure. We also synthesized and characteri zed Be0.5(+/-0.1)B4.9(+/-0.3)N, a new ternary material with the alpha- rhombohedral B structure with refined hexagonal cell parameters of a(h )=5.487(5) Angstrom and c(h)=12.486(14) Angstrom. By comparison of the features at the core-loss edges of Be0.5(+/-0.1)B4.9(+/-0.3)N, we con clude that most N forms N-2 pairs between the icosahedra and Be substi tutes for B within the icosahedra. (C) 1997 Academic Press.