DOE OSTI2020
NbCrGe is alpha-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are six inequivalent Nb sites. In the first Nb site, Nb is bonded in a 5-coordinate geometry to four Nb, seven Cr, and five Ge atoms. There are a spread of Nb–Nb bond distances ranging from 2.81–3.15 Å. There are a spread of Nb–Cr bond distances ranging from 2.94–3.02 Å. There are a spread of Nb–Ge bond distances ranging from 2.88–2.91 Å. In the second Nb site, Nb is bonded in a 1-coordinate geometry to four Nb, five Cr, and seven Ge atoms. The Nb–Nb bond length is 3.02 Å. There are a spread of Nb–Cr bond distances ranging from 2.81–3.14 Å. There are a spread of Nb–Ge bond distances ranging from 2.79–3.02 Å. In the third Nb site, Nb is bonded in a 1-coordinate geometry to four Nb, five Cr, and seven Ge atoms. There are two shorter (3.11 Å) and one longer (3.15 Å) Nb–Nb bond lengths. There are a spread of Nb–Cr bond distances ranging from 2.81–3.14 Å. There are a spread of Nb–Ge bond distances ranging from 2.79–3.02 Å. In the fourth Nb site, Nb is bonded in a 5-coordinate geometry to four Nb, seven Cr, and five Ge atoms. There are a spread of Nb–Cr bond distances ranging from 2.94–3.02 Å. There are a spread of Nb–Ge bond distances ranging from 2.88–2.91 Å. In the fifth Nb site, Nb is bonded in a 1-coordinate geometry to four Nb, five Cr, and seven Ge atoms. The Nb–Nb bond length is 3.02 Å. There are a spread of Nb–Cr bond distances ranging from 2.81–3.14 Å. There are a spread of Nb–Ge bond distances ranging from 2.79–3.02 Å. In the sixth Nb site, Nb is bonded in a 5-coordinate geometry to four Nb, seven Cr, and five Ge atoms. The Nb–Nb bond length is 2.81 Å. There are a spread of Nb–Cr bond distances ranging from 2.94–3.02 Å. There are a spread of Nb–Ge bond distances ranging from 2.88–2.91 Å. There are two inequivalent Cr sites. In the first Cr site, Cr is bonded in a 12-coordinate geometry to six Nb, two equivalent Cr, and four Ge atoms. Both Cr–Cr bond lengths are 2.37 Å. There are a spread of Cr–Ge bond distances ranging from 2.49–2.53 Å. In the second Cr site, Cr is bonded to six Nb, four Cr, and two equivalent Ge atoms to form distorted CrNb6Cr4Ge2 cuboctahedra that share corners with four equivalent CrNb6Cr4Ge2 cuboctahedra, corners with ten GeNb6Cr2Ge4 cuboctahedra, edges with two equivalent CrNb6Cr4Ge2 cuboctahedra, edges with four equivalent GeNb6Cr2Ge4 cuboctahedra, faces with four equivalent CrNb6Cr4Ge2 cuboctahedra, and faces with eight GeNb6Cr6 cuboctahedra. There are one shorter (2.48 Å) and one longer (2.56 Å) Cr–Cr bond lengths. There are one shorter (2.54 Å) and one longer (2.65 Å) Cr–Ge bond lengths. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded to six Nb and six Cr atoms to form GeNb6Cr6 cuboctahedra that share corners with fourteen GeNb6Cr6 cuboctahedra, edges with six GeNb6Cr6 cuboctahedra, faces with four equivalent GeNb6Cr2Ge4 cuboctahedra, and faces with eight equivalent CrNb6Cr4Ge2 cuboctahedra. In the second Ge site, Ge is bonded to six Nb, two equivalent Cr, and four Ge atoms to form distorted GeNb6Cr2Ge4 cuboctahedra that share corners with six equivalent CrNb6Cr4Ge2 cuboctahedra, corners with eight GeNb6Cr6 cuboctahedra, edges with two equivalent GeNb6Cr2Ge4 cuboctahedra, edges with four equivalent CrNb6Cr4Ge2 cuboctahedra, faces with two equivalent CrNb6Cr4Ge2 cuboctahedra, and faces with ten GeNb6Cr6 cuboctahedra. There are a spread of Ge–Ge bond distances ranging from 2.47–2.64 Å. In the third Ge site, Ge is bonded to six Nb, two equivalent Cr, and four equivalent Ge atoms to form distorted GeNb6Cr2Ge4 cuboctahedra that share corners with six GeNb6Cr6 cuboctahedra, corners with eight equivalent CrNb6Cr4Ge2 cuboctahedra, edges with six GeNb6Cr6 cuboctahedra, faces with four equivalent CrNb6Cr4Ge2 cuboctahedra, and faces with eight equivalent GeNb6Cr2Ge4 cuboctahedra.