Materials Data on Pr9Al5Se21 by Materials Project
Pr9Al5Se21 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are six inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 3.00–3.19 Å. In the second Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.36 Å. In the third Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.30 Å. In the fourth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.97–3.19 Å. In the fifth Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.35 Å. In the sixth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 3.00–3.32 Å. There are six inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Al–Se bond distances ranging from 2.36–2.40 Å. In the second Al3+ site, Al3+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Al–Se bond distances ranging from 2.36–2.40 Å. In the third Al3+ site, Al3+ is bonded to six Se2- atoms to form face-sharing AlSe6 octahedra. There are three shorter (2.59 Å) and three longer (2.67 Å) Al–Se bond lengths. In the fourth Al3+ site, Al3+ is bonded to six Se2- atoms to form distorted face-sharing AlSe6 octahedra. There are three shorter (2.49 Å) and three longer (2.82 Å) Al–Se bond lengths. In the fifth Al3+ site, Al3+ is bonded to six Se2- atoms to form distorted face-sharing AlSe6 octahedra. There are three shorter (2.49 Å) and three longer (2.83 Å) Al–Se bond lengths. In the sixth Al3+ site, Al3+ is bonded to six Se2- atoms to form face-sharing AlSe6 octahedra. There are three shorter (2.59 Å) and three longer (2.66 Å) Al–Se bond lengths. There are fourteen inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al tetrahedra that share corners with three SePr3Al2 square pyramids and corners with three SePr3Al trigonal pyramids. In the second Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al tetrahedra that share corners with three SePr3Al2 square pyramids and corners with three SePr3Al trigonal pyramids. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the fifth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the sixth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the seventh Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the eighth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Pr3+ and one Al3+ atom. In the tenth Se2- site, Se2- is bonded to three Pr3+ and two Al3+ atoms to form distorted SePr3Al2 square pyramids that share corners with three SePr3Al tetrahedra, a cornercorner with one SePr3Al trigonal pyramid, edges with two equivalent SePr3Al trigonal pyramids, and faces with two equivalent SePr3Al2 square pyramids. In the eleventh Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al trigonal pyramids that share a cornercorner with one SePr3Al2 square pyramid, corners with three SePr3Al tetrahedra, edges with two equivalent SePr3Al2 square pyramids, and edges with two equivalent SePr3Al trigonal pyramids. In the twelfth Se2- site, Se2- is bonded to three Pr3+ and two Al3+ atoms to form distorted SePr3Al2 square pyramids that share corners with three SePr3Al tetrahedra, a cornercorner with one SePr3Al trigonal pyramid, edges with two equivalent SePr3Al trigonal pyramids, and faces with two equivalent SePr3Al2 square pyramids. In the thirteenth Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al trigonal pyramids that share a cornercorner with one SePr3Al2 square pyramid, corners with three SePr3Al tetrahedra, edges with two equivalent SePr3Al2 square pyramids, and edges with two equivalent SePr3Al trigonal pyramids. In the fourteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Pr3+ and one Al3+ atom.