Materials Data on Ca3Mn2O7 by Materials Project

Abstract

Ca3Mn2O7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. There are four shorter (2.68 Å) and eight longer (2.69 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.70 Å. Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with five equivalent MnO6 octahedra and faces with four equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There is five shorter (1.90 Å) and one longer (1.94 Å) Mn–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Ca2+ and two equivalent Mn4+ atoms. In the second O2- site, O2- is bonded to five equivalent Ca2+ and one Mn4+ atom to form a mixture of distorted corner and edge-sharing OCa5Mn octahedra. The corner-sharing octahedral tilt angles are 12°. In the third O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ca2+ and two equivalent Mn4+ atoms.