Materials Data on Sm5(SiB4)2 by Materials Project
Sm5Si2B8 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Sm+2.80+ sites. In the first Sm+2.80+ site, Sm+2.80+ is bonded in a 12-coordinate geometry to nine B+0.75- and three equivalent Si4- atoms. There are a spread of Sm–B bond distances ranging from 2.70–3.03 Å. There are one shorter (3.16 Å) and two longer (3.20 Å) Sm–Si bond lengths. In the second Sm+2.80+ site, Sm+2.80+ is bonded to two equivalent B+0.75- and four equivalent Si4- atoms to form corner-sharing SmSi4B2 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Sm–B bond lengths are 2.88 Å. All Sm–Si bond lengths are 2.97 Å. There are three inequivalent B+0.75- sites. In the first B+0.75- site, B+0.75- is bonded in a 9-coordinate geometry to four equivalent Sm+2.80+ and five B+0.75- atoms. There are a spread of B–B bond distances ranging from 1.79–1.84 Å. In the second B+0.75- site, B+0.75- is bonded in a 3-coordinate geometry to six equivalent Sm+2.80+ and three B+0.75- atoms. The B–B bond length is 1.89 Å. In the third B+0.75- site, B+0.75- is bonded in a 9-coordinate geometry to five Sm+2.80+ and four equivalent B+0.75- atoms. Si4- is bonded in a 9-coordinate geometry to eight Sm+2.80+ and one Si4- atom. The Si–Si bond length is 2.35 Å.