DOE OSTI2020
TbIr2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Tb is bonded in a 8-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.15 Å) and four longer (3.26 Å) Tb–Ir bond lengths. There are four shorter (3.17 Å) and four longer (3.19 Å) Tb–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent Tb and four equivalent Si atoms to form distorted IrTb4Si4 tetrahedra that share corners with twelve equivalent SiTb4Ir4 tetrahedra, edges with two equivalent SiTb4Ir4 tetrahedra, edges with four equivalent IrTb4Si4 tetrahedra, and faces with four equivalent IrTb4Si4 tetrahedra. All Ir–Si bond lengths are 2.44 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Tb and five Si atoms. There are one shorter (2.38 Å) and four longer (2.43 Å) Ir–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Tb and four equivalent Ir atoms to form distorted SiTb4Ir4 tetrahedra that share corners with twelve equivalent IrTb4Si4 tetrahedra, edges with two equivalent IrTb4Si4 tetrahedra, edges with four equivalent SiTb4Ir4 tetrahedra, and faces with four equivalent SiTb4Ir4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Tb and five Ir atoms.