DOI: 10.17188/1652080
title: Materials Data on Na9Sm(SiSe3)4 by Materials Project

description: Na9Sm(SiSe3)4 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share a cornercorner with one SmSe6 octahedra, corners with three NaSe6 octahedra, corners with two SiSiSe3 tetrahedra, an edgeedge with one SmSe6 octahedra, edges with nine NaSe6 octahedra, and edges with two SiSiSe3 tetrahedra. The corner-sharing octahedra tilt angles range from 5–8°. There are a spread of Na–Se bond distances ranging from 2.94–3.26 Å. In the second Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share a cornercorner with one SmSe6 octahedra, corners with three NaSe6 octahedra, corners with two SiSiSe3 tetrahedra, an edgeedge with one SmSe6 octahedra, edges with nine NaSe6 octahedra, and edges with two SiSiSe3 tetrahedra. The corner-sharing octahedra tilt angles range from 6–9°. There are a spread of Na–Se bond distances ranging from 2.96–3.17 Å. In the third Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share a cornercorner with one SmSe6 octahedra, corners with three NaSe6 octahedra, corners with two SiSiSe3 tetrahedra, an edgeedge with one SmSe6 octahedra, edges with nine NaSe6 octahedra, and edges with two SiSiSe3 tetrahedra. The corner-sharing octahedra tilt angles range from 7–8°. There are a spread of Na–Se bond distances ranging from 2.97–3.18 Å. In the fourth Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share corners with six NaSe6 octahedra, corners with six SiSiSe3 tetrahedra, and edges with nine NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 6–8°. There are four shorter (3.09 Å) and two longer (3.11 Å) Na–Se bond lengths. In the fifth Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share corners with six NaSe6 octahedra, corners with six SiSiSe3 tetrahedra, an edgeedge with one SmSe6 octahedra, and edges with eight NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 5–9°. There are a spread of Na–Se bond distances ranging from 3.08–3.15 Å. In the sixth Na1+ site, Na1+ is bonded to six Se1- atoms to form NaSe6 octahedra that share corners with six NaSe6 octahedra, corners with six SiSiSe3 tetrahedra, edges with two equivalent SmSe6 octahedra, and edges with seven NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 7–8°. There are a spread of Na–Se bond distances ranging from 3.03–3.11 Å. Sm3+ is bonded to six Se1- atoms to form SmSe6 octahedra that share corners with six NaSe6 octahedra, corners with six SiSiSe3 tetrahedra, and edges with nine NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 7–8°. There are a spread of Sm–Se bond distances ranging from 2.95–2.98 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to one Si and three Se1- atoms to form distorted SiSiSe3 tetrahedra that share a cornercorner with one SmSe6 octahedra, corners with three SeNa5Si octahedra, corners with eight NaSe6 octahedra, and edges with three NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 18–80°. The Si–Si bond length is 2.35 Å. There are a spread of Si–Se bond distances ranging from 2.28–2.36 Å. In the second Si site, Si is bonded to one Si and three Se1- atoms to form distorted SiSiSe3 tetrahedra that share corners with two equivalent SmSe6 octahedra, corners with three SeNa4SmSi octahedra, corners with seven NaSe6 octahedra, and edges with three NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 18–78°. The Si–Si bond length is 2.32 Å. There are a spread of Si–Se bond distances ranging from 2.27–2.33 Å. There are six inequivalent Se1- sites. In the first Se1- site, Se1- is bonded to five Na1+ and one Si atom to form SeNa5Si octahedra that share corners with seven SeNa4SmSi octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 3–89°. In the second Se1- site, Se1- is bonded to four Na1+, one Sm3+, and one Si atom to form distorted SeNa4SmSi octahedra that share corners with seven SeNa5Si octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 3–92°. In the third Se1- site, Se1- is bonded to four Na1+, one Sm3+, and one Si atom to form SeNa4SmSi octahedra that share corners with seven SeNa5Si octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 1–91°. In the fourth Se1- site, Se1- is bonded to five Na1+ and one Si atom to form SeNa5Si octahedra that share corners with seven SeNa5Si octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 1–92°. In the fifth Se1- site, Se1- is bonded to five Na1+ and one Si atom to form SeNa5Si octahedra that share corners with seven SeNa5Si octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 1–89°. In the sixth Se1- site, Se1- is bonded to four Na1+, one Sm3+, and one Si atom to form distorted SeNa4SmSi octahedra that share corners with seven SeNa5Si octahedra, a cornercorner with one SiSiSe3 tetrahedra, and edges with ten SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 3–93°.