DOE OSTI2020
U8Bi2O19 is alpha bismuth trifluoride-derived structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent U4+ sites. In the first U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.24–2.41 Å. In the second U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.32–2.36 Å. In the third U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.34–2.36 Å. In the fourth U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.35–2.37 Å. In the fifth U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are one shorter (2.35 Å) and seven longer (2.36 Å) U–O bond lengths. In the sixth U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.35 Å) and four longer (2.36 Å) U–O bond lengths. In the seventh U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.32–2.36 Å. In the eighth U4+ site, U4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.24–2.40 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.34–2.52 Å. In the second Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.33 Å) and four longer (2.50 Å) Bi–O bond lengths. There are nineteen inequivalent O2- sites. In the first O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the second O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the third O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the fourth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the fifth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the sixth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the seventh O2- site, O2- is bonded to four U4+ atoms to form OU4 tetrahedra that share corners with sixteen OU4 tetrahedra and edges with six OU2Bi2 tetrahedra. In the eighth O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OU2Bi2 tetrahedra. In the ninth O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form distorted OU2Bi2 tetrahedra that share corners with fourteen OU4 tetrahedra and edges with five OU2Bi2 tetrahedra. In the tenth O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form distorted OU2Bi2 tetrahedra that share corners with twelve OU2Bi2 tetrahedra and edges with six OBi4 tetrahedra. In the eleventh O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra. In the twelfth O2- site, O2- is bonded to two equivalent U4+ and two equivalent Bi3+ atoms to form distorted OU2Bi2 tetrahedra that share corners with fourteen OBi4 tetrahedra and edges with five OU2Bi2 tetrahedra. In the thirteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the fourteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the fifteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the sixteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the seventeenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the eighteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra. In the nineteenth O2- site, O2- is bonded to four U4+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra.