DOE OSTI2020
Rb5Zr4F21 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are five inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Rb–F bond distances ranging from 2.79–3.44 Å. In the second Rb1+ site, Rb1+ is bonded to twelve F1- atoms to form distorted RbF12 cuboctahedra that share a cornercorner with one ZrF6 octahedra, a cornercorner with one ZrF7 pentagonal bipyramid, edges with three ZrF7 pentagonal bipyramids, and a faceface with one ZrF6 octahedra. The corner-sharing octahedral tilt angles are 39°. There are a spread of Rb–F bond distances ranging from 2.89–3.45 Å. In the third Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Rb–F bond distances ranging from 2.76–3.23 Å. In the fourth Rb1+ site, Rb1+ is bonded in a 11-coordinate geometry to eleven F1- atoms. There are a spread of Rb–F bond distances ranging from 2.82–3.50 Å. In the fifth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Rb–F bond distances ranging from 2.79–3.28 Å. There are four inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to seven F1- atoms to form ZrF7 pentagonal bipyramids that share a cornercorner with one ZrF6 octahedra, a cornercorner with one ZrF7 pentagonal bipyramid, and edges with two equivalent RbF12 cuboctahedra. The corner-sharing octahedral tilt angles are 26°. There are a spread of Zr–F bond distances ranging from 2.01–2.23 Å. In the second Zr4+ site, Zr4+ is bonded to six F1- atoms to form ZrF6 octahedra that share a cornercorner with one RbF12 cuboctahedra, a cornercorner with one ZrF7 pentagonal bipyramid, and a faceface with one RbF12 cuboctahedra. There are a spread of Zr–F bond distances ranging from 2.00–2.15 Å. In the third Zr4+ site, Zr4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Zr–F bond distances ranging from 2.03–2.28 Å. In the fourth Zr4+ site, Zr4+ is bonded to seven F1- atoms to form distorted ZrF7 pentagonal bipyramids that share a cornercorner with one RbF12 cuboctahedra, a cornercorner with one ZrF7 pentagonal bipyramid, and an edgeedge with one RbF12 cuboctahedra. There are a spread of Zr–F bond distances ranging from 2.02–2.28 Å. There are twenty-one inequivalent F1- sites. In the first F1- site, F1- is bonded in a 1-coordinate geometry to four Rb1+ and one Zr4+ atom. In the second F1- site, F1- is bonded in a 1-coordinate geometry to three Rb1+ and one Zr4+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to four Rb1+ and one Zr4+ atom. In the fourth F1- site, F1- is bonded in a 1-coordinate geometry to three Rb1+ and one Zr4+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to three Rb1+ and one Zr4+ atom. In the sixth F1- site, F1- is bonded in a 1-coordinate geometry to three Rb1+ and one Zr4+ atom. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one Rb1+ and two Zr4+ atoms. In the eighth F1- site, F1- is bonded in a 1-coordinate geometry to two Rb1+ and one Zr4+ atom. In the ninth F1- site, F1- is bonded in a 1-coordinate geometry to three Rb1+ and one Zr4+ atom. In the tenth F1- site, F1- is bonded in a distorted single-bond geometry to three Rb1+ and one Zr4+ atom. In the eleventh F1- site, F1- is bonded in a 2-coordinate geometry to two Rb1+ and two Zr4+ atoms. In the twelfth F1- site, F1- is bonded in a distorted single-bond geometry to three Rb1+ and one Zr4+ atom. In the thirteenth F1- site, F1- is bonded in a distorted single-bond geometry to two Rb1+ and one Zr4+ atom. In the fourteenth F1- site, F1- is bonded in a distorted bent 120 degrees geometry to one Rb1+ and two Zr4+ atoms. In the fifteenth F1- site, F1- is bonded in a 1-coordinate geometry to three Rb1+ and one Zr4+ atom. In the sixteenth F1- site, F1- is bonded in a distorted bent 120 degrees geometry to one Rb1+ and two Zr4+ atoms. In the seventeenth F1- site, F1- is bonded in a distorted single-bond geometry to three Rb1+ and one Zr4+ atom. In the eighteenth F1- site, F1- is bonded in a bent 150 degrees geometry to one Rb1+ and two Zr4+ atoms. In the nineteenth F1- site, F1- is bonded in a bent 150 degrees geometry to two Zr4+ atoms. In the twentieth F1- site, F1- is bonded in a 1-coordinate geometry to four Rb1+ and one Zr4+ atom. In the twenty-first F1- site, F1- is bonded in a distorted linear geometry to two Zr4+ atoms.