DOE OSTI2020
Cs4NaHf3H2F19 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are four inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Cs–F bond distances ranging from 2.94–3.24 Å. In the second Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Cs–F bond distances ranging from 3.03–3.21 Å. In the third Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve F1- atoms. There are a spread of Cs–F bond distances ranging from 3.04–3.60 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Cs–F bond distances ranging from 2.94–3.43 Å. Na1+ is bonded to six F1- atoms to form NaF6 octahedra that share corners with two equivalent HfF7 pentagonal bipyramids. There are a spread of Na–F bond distances ranging from 2.21–2.42 Å. There are three inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Hf–F bond distances ranging from 2.00–2.26 Å. In the second Hf4+ site, Hf4+ is bonded to seven F1- atoms to form HfF7 pentagonal bipyramids that share corners with two equivalent NaF6 octahedra and a cornercorner with one HfF7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 52°. There are a spread of Hf–F bond distances ranging from 2.00–2.15 Å. In the third Hf4+ site, Hf4+ is bonded to seven F1- atoms to form distorted corner-sharing HfF7 pentagonal bipyramids. There are four shorter (2.03 Å) and three longer (2.14 Å) Hf–F bond lengths. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two F1- atoms. There is one shorter (1.01 Å) and one longer (1.37 Å) H–F bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two F1- atoms. There is one shorter (1.01 Å) and one longer (1.37 Å) H–F bond length. There are fourteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one Hf4+ atom. In the second F1- site, F1- is bonded in a 3-coordinate geometry to one Cs1+ and two Hf4+ atoms. In the third F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Hf4+, and one H1+ atom. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Hf4+, and one H1+ atom. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+, one Na1+, and one Hf4+ atom. In the sixth F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+, one Na1+, and one H1+ atom. In the seventh F1- site, F1- is bonded in a 3-coordinate geometry to one Cs1+ and two Hf4+ atoms. In the eighth F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+, one Na1+, and one H1+ atom. In the ninth F1- site, F1- is bonded in a bent 150 degrees geometry to two Cs1+, one Na1+, and one Hf4+ atom. In the tenth F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one Hf4+ atom. In the eleventh F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+ and two Hf4+ atoms. In the twelfth F1- site, F1- is bonded in a linear geometry to two Hf4+ atoms. In the thirteenth F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Hf4+ atom. In the fourteenth F1- site, F1- is bonded in a distorted single-bond geometry to two Cs1+ and one Hf4+ atom.