Materials Data on CaSmAl3O7 by Materials Project
CaSmAl3O7 crystallizes in the orthorhombic Cmm2 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 2.45–2.95 Å. Sm3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sm–O bond distances ranging from 2.37–2.85 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.77 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There is one shorter (1.75 Å) and three longer (1.77 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.74–1.78 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Al3+ atoms to form distorted OCa2Al2 tetrahedra that share corners with four OCaSm2Al tetrahedra and edges with two equivalent OCa2SmAl tetrahedra. In the second O2- site, O2- is bonded to two equivalent Sm3+ and two equivalent Al3+ atoms to form a mixture of distorted corner and edge-sharing OSm2Al2 tetrahedra. In the third O2- site, O2- is bonded to one Ca2+, two equivalent Sm3+, and one Al3+ atom to form distorted OCaSm2Al tetrahedra that share corners with six OCa2Al2 tetrahedra and edges with two OSm2Al2 tetrahedra. In the fourth O2- site, O2- is bonded to two equivalent Ca2+, one Sm3+, and one Al3+ atom to form a mixture of distorted corner and edge-sharing OCa2SmAl tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Sm3+, and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Sm3+, and two Al3+ atoms.