DOI: 10.17188/1682007
title: Materials Data on Mn2CrGa3Se8 by Materials Project

description: CrMnGaSe4MnGa2Se4 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three CrMnGaSe4 sheets oriented in the (0, 0, 1) direction and three MnGa2Se4 sheets oriented in the (0, 0, 1) direction. In each CrMnGaSe4 sheet, Cr3+ is bonded to four Se2- atoms to form CrSe4 tetrahedra that share corners with three equivalent GaSe6 octahedra and corners with six equivalent CrSe4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. All Cr–Se bond lengths are 2.46 Å. Mn2+ is bonded to four Se2- atoms to form MnSe4 tetrahedra that share corners with three equivalent GaSe6 octahedra and corners with six equivalent MnSe4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are three shorter (2.46 Å) and one longer (2.52 Å) Mn–Se bond lengths. Ga3+ is bonded to six Se2- atoms to form GaSe6 octahedra that share corners with three equivalent CrSe4 tetrahedra, corners with three equivalent MnSe4 tetrahedra, and edges with six equivalent GaSe6 octahedra. There are three shorter (2.64 Å) and three longer (2.67 Å) Ga–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three equivalent Cr3+ atoms. In the second Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three equivalent Mn2+ atoms. In the third Se2- site, Se2- is bonded to one Cr3+ and three equivalent Ga3+ atoms to form a mixture of distorted edge and corner-sharing SeCrGa3 trigonal pyramids. In the fourth Se2- site, Se2- is bonded to one Mn2+ and three equivalent Ga3+ atoms to form distorted SeMnGa3 trigonal pyramids that share corners with nine SeMnGa3 trigonal pyramids and edges with three equivalent SeCrGa3 trigonal pyramids. In each MnGa2Se4 sheet, Mn2+ is bonded to four Se2- atoms to form MnSe4 tetrahedra that share corners with three equivalent GaSe6 octahedra and corners with six equivalent MnSe4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There are three shorter (2.45 Å) and one longer (2.55 Å) Mn–Se bond lengths. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to six Se2- atoms to form GaSe6 octahedra that share corners with three equivalent MnSe4 tetrahedra, corners with three equivalent GaSe4 tetrahedra, and edges with six equivalent GaSe6 octahedra. There are three shorter (2.61 Å) and three longer (2.70 Å) Ga–Se bond lengths. In the second Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with three equivalent GaSe6 octahedra and corners with six equivalent GaSe4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are one shorter (2.42 Å) and three longer (2.50 Å) Ga–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three equivalent Ga3+ atoms. In the second Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three equivalent Mn2+ atoms. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to four Ga3+ atoms. In the fourth Se2- site, Se2- is bonded to one Mn2+ and three equivalent Ga3+ atoms to form distorted corner-sharing SeMnGa3 tetrahedra.