Materials Data on SrCaU2O8 by Materials Project
SrCaU2O8 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are six shorter (2.53 Å) and two longer (2.62 Å) Sr–O bond lengths. Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Ca–O bond lengths are 2.47 Å. U6+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 1.99–2.32 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to one Sr2+ and three equivalent U6+ atoms to form distorted OSrU3 tetrahedra that share corners with sixteen OCa3U tetrahedra and edges with six OSr3U tetrahedra. In the second O2- site, O2- is bonded to one Ca2+ and three equivalent U6+ atoms to form a mixture of distorted edge and corner-sharing OCaU3 tetrahedra. In the third O2- site, O2- is bonded to three equivalent Sr2+ and one U6+ atom to form distorted OSr3U tetrahedra that share corners with sixteen OSrU3 tetrahedra and edges with six OSr3U tetrahedra. The O–U bond length is 1.99 Å. In the fourth O2- site, O2- is bonded to three equivalent Ca2+ and one U6+ atom to form a mixture of distorted edge and corner-sharing OCa3U tetrahedra. In the fifth O2- site, O2- is bonded to three equivalent Sr2+ and one U6+ atom to form distorted OSr3U tetrahedra that share corners with sixteen OSrU3 tetrahedra and edges with six OSr3U tetrahedra. The O–U bond length is 1.99 Å. In the sixth O2- site, O2- is bonded to three equivalent Ca2+ and one U6+ atom to form a mixture of distorted edge and corner-sharing OCa3U tetrahedra. All O–Ca bond lengths are 2.47 Å. The O–U bond length is 1.99 Å. In the seventh O2- site, O2- is bonded to three equivalent Sr2+ and one U6+ atom to form distorted OSr3U tetrahedra that share corners with sixteen OSrU3 tetrahedra and edges with six OSr3U tetrahedra. All O–Sr bond lengths are 2.53 Å.