DOE OSTI2020
RbMgPO4 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Rb–O bond distances ranging from 2.84–3.15 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 2.93–3.51 Å. In the third Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 2.80–3.43 Å. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with four PO4 tetrahedra. There is two shorter (1.94 Å) and two longer (1.95 Å) Mg–O bond length. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with four PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 1.93–1.97 Å. In the third Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 trigonal bipyramids that share corners with three PO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, and an edgeedge with one PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 1.96–2.28 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MgO4 tetrahedra and a cornercorner with one MgO5 trigonal bipyramid. All P–O bond lengths are 1.55 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four MgO4 tetrahedra. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Rb1+, one Mg2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Rb1+, one Mg2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Rb1+, one Mg2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Rb1+, one Mg2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Rb1+, one Mg2+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Rb1+, two equivalent Mg2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one Mg2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one Mg2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one Mg2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one Mg2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to three Rb1+, one Mg2+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Rb1+, one Mg2+, and one P5+ atom.