Materials Data on FeCuSe2 by Materials Project
CuFeSe2 is Lavarevi\'{c}ite-like structured and crystallizes in the tetragonal P-42c space group. The structure is three-dimensional. Fe3+ is bonded to four equivalent Se2- atoms to form FeSe4 tetrahedra that share corners with four equivalent FeSe4 tetrahedra, corners with four equivalent CuSe4 tetrahedra, and edges with two equivalent CuSe4 tetrahedra. All Fe–Se bond lengths are 2.40 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share edges with two equivalent CuSe4 tetrahedra and edges with four equivalent FeSe4 tetrahedra. All Cu–Se bond lengths are 2.47 Å. In the second Cu1+ site, Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with eight equivalent FeSe4 tetrahedra and edges with two equivalent CuSe4 tetrahedra. All Cu–Se bond lengths are 2.45 Å. Se2- is bonded to two equivalent Fe3+ and two Cu1+ atoms to form a mixture of distorted edge and corner-sharing SeFe2Cu2 tetrahedra.