The nature of the chemical bonding in boron carbide, B13C2. I. Structure refinement

Abstract

The crystal structure of synthetic BI3C 2 has been investigated by X-ray diffraction. Atomic parameters were determined from both conventional refinement techniques, with the spherical-atom model, and multi-0567-7408/79/051052-08501.00 pole expansion refinement. The analysis of the results shows the scale factor and some of the vibrational parameters to be considerably biased by bonding effects. Bias could be reduced by high-order refinements leading to parameters which agree with the results of the multipole expansion refinement within the

Electronic structures and mechanical properties of boron and boron-rich crystals (Part I)

“…The icosahedron-based structure was first identified for boron carbide, which is formally referred to as B 12 C 3 or more shortly as B 4 C [33,34]. The true structures became more complicated as the study progressed [35][36][37][38][39][40][41]. The composition varies in some range, typically from B 12 C 3 to B 13 C 2 , but more C-poor compounds exist [42].…”

Thermoelectric Properties of Hot-pressed Boron Suboxide (B<SUB>6</SUB>O)

“…Figure 1 illustrates schematic crystal structures of B 4 C and B 6 O. Boron carbide consists of B 12 or B 11 C icosahedrons at the vertices of a rhombohedral unit cell and three-atom chain of CBC or CBB at the center of the rhombohedron. [10][11][12][13][14][15][16] Boron carbide has a wide nonstoichiometric composition region from B 4 C to B 10.5 C with different B to C ratio in the icosahedrons and three-atom chains. 12,14,16) Carbon-saturated boron carbide, B 4 C (B 12 C 3 ), consists of B 11 C icosahedrons and CBC three atomic chains (B 11 C-CBC).…”

Evidence for multiple polytypes of semiconducting boron carbide (C2B10) from electronic structure

“…Generally these different polytypes have been associated with changing composition such as increasing the boron concentration [3,4,6,10,[24][25][26][27][28][29][30][31][32][33][34] or replacing carbon with other main group elements such as phosphorus [35,36], aluminium [37][38][39][40][41] and other main group elements. We have identified different polytypes of the semiconducting boron carbides with large direct band gaps (materials formed from para-carborane and dimeric phosphorus bridged ortho-carborane (C 2 B 10 H 10 PCl) 2 ) and those with smaller band gaps (materials formed from ortho-carborane and meta-carborane).…”