DOE OSTI2020
Er2CuSi3 is hexagonal omega structure-derived structured and crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Er sites. In the first Er site, Er is bonded to four equivalent Cu and eight Si atoms to form a mixture of edge and face-sharing ErCu4Si8 cuboctahedra. All Er–Cu bond lengths are 3.08 Å. There are six shorter (3.01 Å) and two longer (3.09 Å) Er–Si bond lengths. In the second Er site, Er is bonded to two equivalent Cu and ten Si atoms to form a mixture of edge and face-sharing ErCu2Si10 cuboctahedra. Both Er–Cu bond lengths are 3.03 Å. There are a spread of Er–Si bond distances ranging from 3.02–3.12 Å. Cu is bonded in a 9-coordinate geometry to six Er and three Si atoms. There are one shorter (2.26 Å) and two longer (2.29 Å) Cu–Si bond lengths. There are three inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to six Er, two equivalent Cu, and one Si atom. The Si–Si bond length is 2.32 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to six Er, one Cu, and two equivalent Si atoms. Both Si–Si bond lengths are 2.36 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to six Er and three Si atoms.