DOE OSTI2020
Eu5Zr3S12 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Eu+2.40+ sites. In the first Eu+2.40+ site, Eu+2.40+ is bonded to seven S2- atoms to form distorted EuS7 pentagonal bipyramids that share corners with two equivalent ZrS6 octahedra, corners with two equivalent EuS7 pentagonal bipyramids, edges with four equivalent ZrS6 octahedra, and edges with two equivalent EuS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. There are a spread of Eu–S bond distances ranging from 2.89–2.91 Å. In the second Eu+2.40+ site, Eu+2.40+ is bonded in a 9-coordinate geometry to nine S2- atoms. There are six shorter (2.99 Å) and three longer (3.41 Å) Eu–S bond lengths. Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with two equivalent EuS7 pentagonal bipyramids, edges with two equivalent ZrS6 octahedra, and edges with four equivalent EuS7 pentagonal bipyramids. There are a spread of Zr–S bond distances ranging from 2.56–2.62 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded to four Eu+2.40+ and one Zr4+ atom to form distorted SEu4Zr trigonal bipyramids that share corners with seven equivalent SEu4Zr trigonal bipyramids, corners with two equivalent SEu2Zr2 trigonal pyramids, edges with five equivalent SEu4Zr trigonal bipyramids, and edges with two equivalent SEu2Zr2 trigonal pyramids. In the second S2- site, S2- is bonded to two equivalent Eu+2.40+ and two equivalent Zr4+ atoms to form distorted SEu2Zr2 trigonal pyramids that share corners with four equivalent SEu4Zr trigonal bipyramids, corners with four equivalent SEu2Zr2 trigonal pyramids, and edges with four equivalent SEu4Zr trigonal bipyramids. In the third S2- site, S2- is bonded in a 5-coordinate geometry to three Eu+2.40+ and two equivalent Zr4+ atoms.