DOI: 10.17188/1191248
title: Materials Data on Pr4Ga2O9 by Materials Project

description: Pr4Ga2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Pr–O bond distances ranging from 2.40–2.77 Å. In the second Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.36–3.01 Å. In the third Pr3+ site, Pr3+ is bonded to six O2- atoms to form PrO6 octahedra that share corners with three equivalent GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, and edges with two equivalent PrO7 hexagonal pyramids. There are a spread of Pr–O bond distances ranging from 2.34–2.49 Å. In the fourth Pr3+ site, Pr3+ is bonded to seven O2- atoms to form distorted PrO7 hexagonal pyramids that share a cornercorner with one GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, edges with two equivalent PrO6 octahedra, an edgeedge with one GaO4 tetrahedra, and an edgeedge with one GaO4 trigonal pyramid. There are a spread of Pr–O bond distances ranging from 2.37–2.62 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 trigonal pyramids that share corners with two equivalent PrO7 hexagonal pyramids, corners with two equivalent PrO6 octahedra, a cornercorner with one GaO4 tetrahedra, and an edgeedge with one PrO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 40–54°. There are a spread of Ga–O bond distances ranging from 1.83–1.89 Å. In the second Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share a cornercorner with one PrO7 hexagonal pyramid, corners with three equivalent PrO6 octahedra, a cornercorner with one GaO4 trigonal pyramid, and an edgeedge with one PrO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Ga–O bond distances ranging from 1.83–1.89 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to three Pr3+ and one Ga3+ atom to form distorted OPr3Ga trigonal pyramids that share corners with three OPr2Ga2 tetrahedra and edges with three OPr4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Pr3+ and one Ga3+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three Pr3+ and one Ga3+ atom. In the fourth O2- site, O2- is bonded to two Pr3+ and two Ga3+ atoms to form a mixture of distorted edge and corner-sharing OPr2Ga2 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Pr3+ and one Ga3+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Pr3+ and one Ga3+ atom. In the seventh O2- site, O2- is bonded to three Pr3+ and one Ga3+ atom to form distorted OPr3Ga tetrahedra that share corners with six OPr2Ga2 tetrahedra, an edgeedge with one OPr2Ga2 tetrahedra, and an edgeedge with one OPr3Ga trigonal pyramid. In the eighth O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share corners with six OPr2Ga2 tetrahedra, edges with three OPr2Ga2 tetrahedra, and an edgeedge with one OPr3Ga trigonal pyramid. In the ninth O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share corners with five OPr2Ga2 tetrahedra, a cornercorner with one OPr3Ga trigonal pyramid, edges with two OPr4 tetrahedra, and an edgeedge with one OPr3Ga trigonal pyramid.