DOE OSTI2020
Cr2Nb is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the tetragonal I-4m2 space group. The structure is three-dimensional. there are three inequivalent Nb sites. In the first Nb site, Nb is bonded in a 6-coordinate geometry to four equivalent Nb and ten Cr atoms. All Nb–Nb bond lengths are 3.06 Å. There are a spread of Nb–Cr bond distances ranging from 2.70–3.04 Å. In the second Nb site, Nb is bonded in a 8-coordinate geometry to six Nb and eight Cr atoms. There are two shorter (3.03 Å) and two longer (3.16 Å) Nb–Nb bond lengths. There are a spread of Nb–Cr bond distances ranging from 2.65–2.85 Å. In the third Nb site, Nb is bonded in a 4-coordinate geometry to four equivalent Nb and ten Cr atoms. There are a spread of Nb–Cr bond distances ranging from 2.70–2.95 Å. There are four inequivalent Cr sites. In the first Cr site, Cr is bonded to four Nb and eight Cr atoms to form a mixture of distorted face and corner-sharing CrNb4Cr8 cuboctahedra. There are a spread of Cr–Cr bond distances ranging from 2.39–2.76 Å. In the second Cr site, Cr is bonded in a 12-coordinate geometry to four Nb and eight Cr atoms. There are a spread of Cr–Cr bond distances ranging from 2.54–2.75 Å. In the third Cr site, Cr is bonded to four Nb and eight Cr atoms to form a mixture of face and corner-sharing CrNb4Cr8 cuboctahedra. There are a spread of Cr–Cr bond distances ranging from 2.60–2.68 Å. In the fourth Cr site, Cr is bonded in a 12-coordinate geometry to six Nb and six Cr atoms.