The boron framework of YB 41 Si 1.2 consists of five B 12 icosahedra ( I1 I5 ) and a B 12 Si 3 polyhedron shown in figure 8a.
42.
The I4 icosahedra link two networks along the " c "-axis and therefore form an infinite chain of icosahedra along this axis as shown in figure 10.
43.
The I4 icosahedra link two networks along the " c "-axis and therefore form an infinite chain of icosahedra along this axis as shown in figure 10.
44.
However, the bonding distances between the apex B atoms ( 0.1619 and 0.1674 nm ) of neighboring I4 icosahedra are usual for the considered metal borides.
45.
The SiB 6 crystal structure contains interconnected icosahedra ( polyhedra with 20 faces ), icosihexahedra ( polyhedra with 26 faces ), as well as isolated silicon and boron atoms.
46.
It can be constructed by creating two coinciding icosahedra in 3-space, and translating each copy in opposite perpendicular directions in 4-space until their separation equals their edge length.
47.
The icosahedra I1 and I2 form a ring centered by the " tube " shown in figure 21b, which probably governs the properties of the ScB 17 C 0.25 crystal.
48.
Due to the size mismatch between the silicon and boron atoms, silicon can be substituted for boron in the B 12 icosahedra up to a limiting stoichiometry corresponding to SiB 2.89.
49.
There is evidence of significant charge transfer from B 2 pairs to the B 12 icosahedra in this structure; in particular, lattice dynamics suggests the presence of significant long-range electrostatic interactions.
50.
The large black spheres are Y atoms, the small blue spheres are Al atoms and the small green spheres are the bridging boron sites; B 12 clusters are depicted as the green icosahedra.
