Materials Data on Cr2CuSe3Br by Materials Project

CuCr2Se3Br is Spinel-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six equivalent Se2- atoms to form CrSe6 octahedra that share corners with six equivalent CuSe3Br tetrahedra and edges with six equivalent CrSe4Br2 octahedra. All Cr–Se bond lengths are 2.54 Å. In the second Cr3+ site, Cr3+ is bonded to four equivalent Se2- and two equivalent Br1- atoms to form CrSe4Br2 octahedra that share corners with six equivalent CuSe3Br tetrahedra and edges with six CrSe6 octahedra. All Cr–Se bond lengths are 2.54 Å. Both Cr–Br bond lengths are 2.58 Å. Cu1+ is bonded to three equivalent Se2- and one Br1- atom to form CuSe3Br tetrahedra that share corners with twelve CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. All Cu–Se bond lengths are 2.39 Å. The Cu–Br bond length is 2.62 Å. Se2- is bonded in a rectangular see-saw-like geometry to three Cr3+ and one Cu1+ atom. Br1- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr3+ and one Cu1+ atom.

CuCr₂Se₃Br为尖晶石衍生结构，结晶于三方晶系R-3m空间群（trigonal R-3m space group）。该结构为三维框架结构。体系中存在两个不等价的Cr³+位点。在第一个Cr³+位点中，Cr³+与6个等价的Se²-原子配位，形成CrSe₆八面体，该八面体与6个等价的CuSe₃Br四面体共享顶点，同时与6个等价的CrSe₄Br₂八面体共享棱边。所有Cr-Se键长均为2.54埃（Å）。在第二个Cr³+位点中，Cr³+与4个等价的Se²-原子和2个等价的Br¹-原子配位，形成CrSe₄Br₂八面体，该八面体与6个等价的CuSe₃Br四面体共享顶点，同时与6个CrSe₆八面体共享棱边。所有Cr-Se键长均为2.54埃，Cr-Br键长均为2.58埃。Cu⁺与3个等价的Se²-原子和1个Br¹-原子配位，形成CuSe₃Br四面体，该四面体与12个CrSe₆八面体共享顶点。共享顶点的八面体倾斜角范围为53°~61°。所有Cu-Se键长均为2.39埃，Cu-Br键长为2.62埃。Se²-原子以矩形跷跷板状几何构型与3个Cr³+和1个Cu⁺原子配位。Br¹-原子以畸变矩形跷跷板状几何构型与3个等价的Cr³+和1个Cu⁺原子配位。