Assertion: boron's form | /r/HasProperty | lattice constants
Facets:
Source sentences:
text: There, B 12 icosahedra form a rhombohedral lattice unit (space group: R3m (No. 166), lattice constants: a = 0.56 nm and c = 1.212 nm) surrounding a C-B-C chain that resides at the center of the lattice unit, and both C atoms bridge the neighboring three icosahedra.