Boron–silicon solid solution: synthesis and crystal structure of a carbon-doped boron-rich SiB n ( n∼30) compound

Abstract

The carbon-doped SiB ∼ 30 compound was obtained during attempts to synthesize by arc-melting boron-rich binaries belonging to the SiB n solid solution (13< n<32). Its crystal structure was determined from X-ray single-crystal intensity data ( R-3 m, Z=1, a=11.0152(3) Å , and c=23.8625(8) Å) and led to the final formula SiB ∼30C 0.35. Carbon is incorporated fortuitously in the structure. The boron framework of these phases slightly differs from that encountered in β-boron. The salient characteristic is the partial occupancy of three interstitial boron sites by silicon and one by carbon atoms. This is in contrast with the structurally related compounds such as SiB ∼36, CrB ∼41, or FeB ∼40, in which only two interstitial sites are partially occupied.