DOE OSTI2020
Th8Y2O19 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are four inequivalent Th4+ sites. In the first Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Th–O bond distances ranging from 2.35–2.46 Å. In the second Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Th–O bond distances ranging from 2.39–2.42 Å. In the third Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.39 Å) and six longer (2.40 Å) Th–O bond lengths. In the fourth Th4+ site, Th4+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Th–O bond lengths are 2.39 Å. Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.23–2.48 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to four Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra. In the second O2- site, O2- is bonded to four Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra. In the third O2- site, O2- is bonded to four Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra. In the fourth O2- site, O2- is bonded to four equivalent Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra. In the fifth O2- site, O2- is bonded to two equivalent Th4+ and two equivalent Y3+ atoms to form OY2Th2 tetrahedra that share corners with twelve OY2Th2 tetrahedra and edges with six OTh4 tetrahedra. In the sixth O2- site, O2- is bonded to four Th4+ atoms to form OTh4 tetrahedra that share corners with sixteen OTh4 tetrahedra and edges with six OY2Th2 tetrahedra. In the seventh O2- site, O2- is bonded to two equivalent Th4+ and two equivalent Y3+ atoms to form OY2Th2 tetrahedra that share corners with fourteen OTh4 tetrahedra and edges with five OY2Th2 tetrahedra. In the eighth O2- site, O2- is bonded to four equivalent Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the ninth O2- site, O2- is bonded to four Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra. In the tenth O2- site, O2- is bonded to four Th4+ atoms to form a mixture of edge and corner-sharing OTh4 tetrahedra.