Materials Data on AlCrFeO4 by Materials Project

FeCrAlO4 is Spinel-derived structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent CrO6 octahedra, and edges with four equivalent AlO6 octahedra. There are four shorter (2.03 Å) and two longer (2.04 Å) Cr–O bond lengths. Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six equivalent CrO6 octahedra and corners with six equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 55–65°. There are two shorter (2.02 Å) and two longer (2.04 Å) Fe–O bond lengths. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent AlO6 octahedra, and edges with four equivalent CrO6 octahedra. There is two shorter (1.92 Å) and four longer (1.96 Å) Al–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cr3+, one Fe2+, and one Al3+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Cr3+, one Fe2+, and two equivalent Al3+ atoms.

FeCrAlO4为尖晶石衍生结构，结晶于正交晶系的Imma空间群，整体为三维晶体架构。
三价铬离子（Cr³+）与六个二价氧离子（O²-）配位形成CrO₆八面体，该八面体与六个等价的FeO₄四面体共享顶点，同时与两个等价的CrO₆八面体、四个等价的AlO₆八面体共享棱边；Cr–O键长分为两组：4条较短键长为2.03 Å，2条较长键长为2.04 Å。
二价铁离子（Fe²+）与四个O²-配位形成FeO₄四面体，该四面体与六个等价的CrO₆八面体及六个等价的AlO₆八面体共享顶点；共顶八面体的倾斜角范围为55°至65°，Fe–O键长分为两组：2条较短键长为2.02 Å，2条较长键长为2.04 Å。
三价铝离子（Al³+）与六个O²-配位形成AlO₆八面体，该八面体与六个等价的FeO₄四面体共享顶点，同时与两个等价的AlO₆八面体、四个等价的CrO₆八面体共享棱边；Al–O键长分为两组：2条较短键长为1.92 Å，4条较长键长为1.96 Å。
体系内存在两个不等价的O²-配位位点：在第一类O²-位点中，O²-以畸变矩形跷跷板型配位环境分别与两个等价的Cr³+、一个Fe²+及一个Al³+结合；在第二类O²-位点中，O²-同样采用畸变矩形跷跷板型配位环境，分别与一个Cr³+、一个Fe²+及两个等价的Al³+结合。