Materials Data on HfCuSi2 by Materials Project
HfCuSi2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Hf is bonded to four equivalent Cu and eight Si atoms to form distorted HfCu4Si8 cuboctahedra that share corners with four equivalent HfCu4Si8 cuboctahedra, edges with eight equivalent HfCu4Si8 cuboctahedra, edges with eight equivalent CuHf4Cu4Si4 cuboctahedra, faces with four equivalent HfCu4Si8 cuboctahedra, and faces with four equivalent CuHf4Cu4Si4 cuboctahedra. All Hf–Cu bond lengths are 3.02 Å. There are four shorter (2.73 Å) and four longer (2.79 Å) Hf–Si bond lengths. Cu is bonded to four equivalent Hf, four equivalent Cu, and four equivalent Si atoms to form CuHf4Cu4Si4 cuboctahedra that share corners with four equivalent CuHf4Cu4Si4 cuboctahedra, edges with eight equivalent HfCu4Si8 cuboctahedra, faces with four equivalent HfCu4Si8 cuboctahedra, and faces with eight equivalent CuHf4Cu4Si4 cuboctahedra. All Cu–Cu bond lengths are 2.61 Å. All Cu–Si bond lengths are 2.42 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to four equivalent Hf and four equivalent Si atoms. All Si–Si bond lengths are 2.61 Å. In the second Si site, Si is bonded in a 4-coordinate geometry to four equivalent Hf and four equivalent Cu atoms.