Materials Data on Hf2CuSi4 by Materials Project

Hf2CuSi4 is Parent of FeAs superconductors-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 10-coordinate geometry to ten Si atoms. There are a spread of Hf–Si bond distances ranging from 2.70–2.97 Å. In the second Hf site, 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 four equivalent HfCu4Si8 cuboctahedra, edges with eight equivalent CuHf4Cu4Si4 cuboctahedra, faces with four equivalent HfCu4Si8 cuboctahedra, and faces with four equivalent CuHf4Cu4Si4 cuboctahedra. There are two shorter (3.01 Å) and two longer (3.02 Å) Hf–Cu bond lengths. There are four shorter (2.73 Å) and four longer (2.77 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 2.60 Å. All Cu–Si bond lengths are 2.41 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to six equivalent Hf and two equivalent Si atoms. Both Si–Si bond lengths are 2.42 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to four Hf and four equivalent Si atoms. All Si–Si bond lengths are 2.60 Å. In the third Si site, Si is bonded in a 8-coordinate geometry to four Hf and four equivalent Si atoms. In the fourth Si site, Si is bonded in a 8-coordinate geometry to four equivalent Hf and four equivalent Cu atoms.