Materials Data on CaPrAl3O7 by Materials Project

Abstract

CaPrAl3O7 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 2.44–2.97 Å. Pr3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.42–2.85 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. There are a spread of Al–O bond distances ranging from 1.75–1.78 Å. In the second 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. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.77 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+, two equivalent Pr3+, and one Al3+ atom to form distorted OCaPr2Al tetrahedra that share corners with six OCa2PrAl tetrahedra and edges with two OPr2Al2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Ca2+, one Pr3+, and one Al3+ atom to form distorted OCa2PrAl tetrahedra that share corners with six OCaPr2Al tetrahedra and edges with two OCa2Al2 tetrahedra. In the third O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Al3+ atoms to form distorted OCa2Al2 tetrahedra that share corners with four OCaPr2Al tetrahedra and edges with two equivalent OCa2PrAl tetrahedra. In the fourth O2- site, O2- is bonded to two equivalent Pr3+ and two equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing OPr2Al2 tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Pr3+, and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Pr3+, and two Al3+ atoms.