Materials Data on Nd2Th2O7 by Materials Project
Th2Nd2O7 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. there are two 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 2.39–2.65 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 2.39–2.49 Å. There are two inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Nd–O bond distances ranging from 2.29–2.44 Å. In the second Nd3+ site, Nd3+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing NdO6 octahedra. The corner-sharing octahedral tilt angles are 66°. There are two shorter (2.38 Å) and four longer (2.44 Å) Nd–O bond lengths. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Th4+ and three Nd3+ atoms to form a mixture of distorted corner and edge-sharing ONd3Th tetrahedra. In the second O2- site, O2- is bonded to four Th4+ atoms to form OTh4 tetrahedra that share corners with sixteen ONd3Th tetrahedra and edges with six ONdTh3 tetrahedra. In the third O2- site, O2- is bonded to three Th4+ and one Nd3+ atom to form a mixture of corner and edge-sharing ONdTh3 tetrahedra. In the fourth O2- site, O2- is bonded to two equivalent Th4+ and two equivalent Nd3+ atoms to form ONd2Th2 tetrahedra that share corners with fourteen ONd3Th tetrahedra and edges with five OTh4 tetrahedra. In the fifth O2- site, O2- is bonded to two equivalent Th4+ and two equivalent Nd3+ atoms to form a mixture of corner and edge-sharing ONd2Th2 tetrahedra.