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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K2HfO2F5 by Materials Project

K2HfO2F5 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded to one O and six F atoms to form distorted KOF6 pentagonal bipyramids that share corners with four equivalent HfO2F5 pentagonal bipyramids, an edgeedge with one KOF6 pentagonal bipyramid, and an edgeedge with one HfO2F5 pentagonal bipyramid. The K–O bond length is 2.97 Å. There are a spread of K–F bond distances ranging from 2.63–2.88 Å. In the second K site, K is bonded in a 7-coordinate geometry to two equivalent O and five F atoms. There are one shorter (2.84 Å) and one longer (3.14 Å) K–O bond lengths. There are a spread of K–F bond distances ranging from 2.68–2.80 Å. Hf is bonded to two equivalent O and five F atoms to form distorted HfO2F5 pentagonal bipyramids that share corners with four equivalent KOF6 pentagonal bipyramids, an edgeedge with one KOF6 pentagonal bipyramid, and an edgeedge with one HfO2F5 pentagonal bipyramid. There are one shorter (2.24 Å) and one longer (2.26 Å) Hf–O bond lengths. There are a spread of Hf–F bond distances ranging from 1.98–2.05 Å. There are two inequivalent O sites. In the first O site, O is bonded in a T-shaped geometry to three K atoms. In the second O site, O is bonded in a 3-coordinate geometry to two equivalent Hf and one O atom. The O–O bond length is 1.42 Å. There are five inequivalent F sites. In the first F site, F is bonded to three K and one Hf atom to form a mixture of distorted corner and edge-sharing FK3Hf tetrahedra. In the second F site, F is bonded in a distorted bent 150 degrees geometry to one K and one Hf atom. In the third F site, F is bonded in a 3-coordinate geometry to two K and one Hf atom. In the fourth F site, F is bonded to three K and one Hf atom to form a mixture of distorted corner and edge-sharing FK3Hf tetrahedra. In the fifth F site, F is bonded in a 3-coordinate geometry to two K and one Hf atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K5Hf3OF17 by Materials Project

K5Hf3OF17 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent K sites. In the first K site, K is bonded in a 9-coordinate geometry to one O and eight F atoms. The K–O bond length is 3.13 Å. There are a spread of K–F bond distances ranging from 2.61–3.20 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight F atoms. There are a spread of K–F bond distances ranging from 2.62–3.01 Å. In the third K site, K is bonded in a 7-coordinate geometry to seven F atoms. There are a spread of K–F bond distances ranging from 2.71–2.83 Å. There are two inequivalent Hf sites. In the first Hf site, Hf is bonded to seven F atoms to form a mixture of edge and corner-sharing HfF7 pentagonal bipyramids. There are a spread of Hf–F bond distances ranging from 2.00–2.18 Å. In the second Hf site, Hf is bonded to seven F atoms to form distorted corner-sharing HfF7 pentagonal bipyramids. There are a spread of Hf–F bond distances ranging from 2.01–2.18 Å. O is bonded in a 2-coordinate geometry to two equivalent K atoms. There are ten inequivalent F sites. In the first F site, F is bonded in a 1-coordinate geometry to three K and one Hf atom. In the second F site, F is bonded in a distorted bent 120 degrees geometry to one K and two equivalent Hf atoms. In the third F site, F is bonded in a 1-coordinate geometry to three K and one Hf atom. In the fourth F site, F is bonded in a 1-coordinate geometry to four equivalent K and one Hf atom. In the fifth F site, F is bonded to three K and one Hf atom to form distorted corner-sharing FK3Hf tetrahedra. In the sixth F site, F is bonded in a distorted trigonal non-coplanar geometry to two K and one Hf atom. In the seventh F site, F is bonded in a linear geometry to two Hf atoms. In the eighth F site, F is bonded in a 4-coordinate geometry to three K and one Hf atom. In the ninth F site, F is bonded in a distorted trigonal non-coplanar geometry to two equivalent K and one Hf atom. In the tenth F site, F is bonded in a 1-coordinate geometry to three K and one Hf atom.

36 MATERIALS SCIENCE↗