DOE OSTI2020
KTbF5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of K–F bond distances ranging from 2.59–2.74 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of K–F bond distances ranging from 2.58–3.21 Å. In the third K1+ site, K1+ is bonded in a 7-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.73–3.11 Å. There are three inequivalent Tb4+ sites. In the first Tb4+ site, Tb4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Tb–F bond distances ranging from 2.24–2.38 Å. In the second Tb4+ site, Tb4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Tb–F bond distances ranging from 2.28–2.44 Å. In the third Tb4+ site, Tb4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Tb–F bond distances ranging from 2.25–2.42 Å. There are fifteen inequivalent F1- sites. In the first F1- site, F1- is bonded to two K1+ and two Tb4+ atoms to form a mixture of distorted corner and edge-sharing FK2Tb2 tetrahedra. In the second F1- site, F1- is bonded in a 2-coordinate geometry to three K1+ and one Tb4+ atom. In the third F1- site, F1- is bonded in a linear geometry to two Tb4+ atoms. In the fourth F1- site, F1- is bonded to two K1+ and two Tb4+ atoms to form a mixture of distorted corner and edge-sharing FK2Tb2 tetrahedra. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Tb4+ atoms. In the sixth F1- site, F1- is bonded in a 1-coordinate geometry to two K1+, one Tb4+, and one F1- atom. The F–F bond length is 2.07 Å. In the seventh F1- site, F1- is bonded to two K1+ and two Tb4+ atoms to form a mixture of distorted corner and edge-sharing FK2Tb2 tetrahedra. In the eighth F1- site, F1- is bonded in a 3-coordinate geometry to two K1+ and one Tb4+ atom. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent K1+, one Tb4+, and one F1- atom. In the tenth F1- site, F1- is bonded to two equivalent K1+ and two Tb4+ atoms to form a mixture of distorted corner and edge-sharing FK2Tb2 tetrahedra. In the eleventh F1- site, F1- is bonded in a bent 150 degrees geometry to two Tb4+ atoms. In the twelfth F1- site, F1- is bonded in a distorted bent 120 degrees geometry to two equivalent Tb4+ atoms. In the thirteenth F1- site, F1- is bonded to two K1+ and two equivalent Tb4+ atoms to form a mixture of distorted corner and edge-sharing FK2Tb2 tetrahedra. In the fourteenth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and one Tb4+ atom. In the fifteenth F1- site, F1- is bonded in a 2-coordinate geometry to three K1+, one Tb4+, and one F1- atom. The F–F bond length is 2.02 Å.