Impact of La doping on the thermochemical heat storage properties of CaMnO3-δ
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CaMnO3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.32–2.64 Å. Mn4+ is bonded to six O2- atoms to form corner-sharing MnO6 octahedra. The corner-sharing octahedra tilt angles range from 26–27°. There is two shorter (1.94 Å) and four longer (1.95 Å) Mn–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Ca2+ and two equivalent Mn4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Mn4+ atoms.
CaMnO3 is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ca2+ is bonded to twelve equivalent O2- atoms to form CaO12 cuboctahedra that share corners with twelve equivalent CaO12 cuboctahedra, faces with six equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. All Ca–O bond lengths are 2.69 Å. Mn4+ is bonded to six equivalent O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO6 octahedra and faces with eight equivalent CaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Mn–O bond lengths are 1.90 Å. O2- is bonded in a distorted linear geometry to four equivalent Ca2+ and two equivalent Mn4+ atoms.
CaMnO3 is (Cubic) Perovskite-like structured and crystallizes in the hexagonal P6_3/mmc 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 six equivalent CaO12 cuboctahedra, corners with six equivalent MnO6 octahedra, faces with eight CaO12 cuboctahedra, and faces with six equivalent MnO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are six shorter (2.70 Å) and six longer (2.83 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with twelve equivalent CaO12 cuboctahedra, faces with six equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. There are six shorter (2.70 Å) and six longer (2.78 Å) Ca–O bond lengths. Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three equivalent CaO12 cuboctahedra, corners with three equivalent MnO6 octahedra, faces with seven CaO12 cuboctahedra, and a faceface with one MnO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There is three shorter (1.88 Å) and three longer (1.93 Å) Mn–O bond length. There are two 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 in a 2-coordinate geometry to four Ca2+ and two equivalent Mn4+ atoms.