The structure of boron carbide is mainly composed of its complex crystal structure, which is characteristic of borides centered on icosahedra. In the crystal structure of boron carbide, B₁₂icosahedra form rhombic lattice units around the C-B-C chain at the center of the unit cell (space group, lattice constant = 0.56 nm and c = 1.212 nm). All carbon atoms bridge three adjacent icosahedra, forming a network plane and stacking along the c-axis to form a layered structure. The two basic structural units of the lattice are B₁₂icosahedra and B6 octahedra. 12
The crystal structure of boron carbide has a hexagonal rhombus lattice with 12 B atoms and 3 C atoms in the unit cell. Its crystal structure consists of tightly bound buckyball-like 12-atom icosahedrons located at the vertices of the rhombus lattice. The structure is completed by a 3-atom linear chain crossing the longest diagonal in the r direction. Boron carbide can have B11C (C-rich B4C has 11 B and 1 C atoms) or B12 (B-rich B13C2 has 12 B atoms) icosahedrons and C-B-C linear chains.
In addition, the rhombohedral structure of boron carbide includes 12 icosahedral atomic clusters, which are interconnected by covalent bonds and have a three-atom chain on the diagonal of the rhombohedron. The dodecahedral structure of polyboron is located at the vertices of the rhombohedron. Boron atoms and carbon atoms can replace each other in the icosahedron and on the atomic chain, which is the main reason why boron carbide has so many isomers. The most widely accepted B4C structure has a B11C icosahedron and a C-B-C atomic chain.
In summary, the crystal structure of boron carbide is a complex network composed of basic structural units such as icosahedra and octahedrons, with high symmetry and stability. These characteristics make boron carbide perform well in industrial applications, especially in wear-resistant materials, neutron absorbers in the nuclear energy field, etc.