DOE OSTI2020
Ca(Ce2Se3)4 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Ca is bonded to eight Se atoms to form distorted CaSe8 hexagonal bipyramids that share corners with eight CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, and faces with eight CeSe8 hexagonal bipyramids. There are a spread of Ca–Se bond distances ranging from 2.99–3.19 Å. There are eight inequivalent Ce sites. In the first Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share a cornercorner with one CaSe8 hexagonal bipyramid, corners with seven CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 3.00–3.17 Å. In the second Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share corners with two equivalent CaSe8 hexagonal bipyramids, corners with six CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 2.99–3.17 Å. In the third Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share a cornercorner with one CaSe8 hexagonal bipyramid, corners with seven CeSe8 hexagonal bipyramids, an edgeedge with one CaSe8 hexagonal bipyramid, edges with three CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 2.99–3.17 Å. In the fourth Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share corners with two equivalent CaSe8 hexagonal bipyramids, corners with six CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 2.99–3.16 Å. In the fifth Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share corners with eight CeSe8 hexagonal bipyramids, edges with two equivalent CaSe8 hexagonal bipyramids, edges with two CeSe8 hexagonal bipyramids, and faces with eight CeSe8 hexagonal bipyramids. There are four shorter (3.00 Å) and four longer (3.16 Å) Ce–Se bond lengths. In the sixth Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share a cornercorner with one CaSe8 hexagonal bipyramid, corners with seven CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 2.99–3.17 Å. In the seventh Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share corners with eight CeSe8 hexagonal bipyramids, edges with four CeSe8 hexagonal bipyramids, faces with two equivalent CaSe8 hexagonal bipyramids, and faces with six CeSe8 hexagonal bipyramids. There are four shorter (3.01 Å) and four longer (3.16 Å) Ce–Se bond lengths. In the eighth Ce site, Ce is bonded to eight Se atoms to form distorted CeSe8 hexagonal bipyramids that share a cornercorner with one CaSe8 hexagonal bipyramid, corners with seven CeSe8 hexagonal bipyramids, an edgeedge with one CaSe8 hexagonal bipyramid, edges with three CeSe8 hexagonal bipyramids, a faceface with one CaSe8 hexagonal bipyramid, and faces with seven CeSe8 hexagonal bipyramids. There are a spread of Ce–Se bond distances ranging from 2.99–3.17 Å. There are twelve inequivalent Se sites. In the first Se site, Se is bonded to one Ca and five Ce atoms to form distorted SeCaCe5 octahedra that share corners with fifteen SeCaCe5 octahedra, edges with six SeCaCe5 octahedra, and faces with five SeCe6 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the second Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the third Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the fourth Se site, Se is bonded to six Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCe6 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the fifth Se site, Se is bonded to six Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCe6 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the sixth Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the seventh Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the eighth Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the ninth Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the tenth Se site, Se is bonded to six Ce atoms to form distorted SeCe6 octahedra that share corners with fifteen SeCaCe5 octahedra, edges with six SeCaCe5 octahedra, and faces with five SeCe6 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the eleventh Se site, Se is bonded to one Ca and five Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCaCe5 octahedra. The corner-sharing octahedra tilt angles range from 17–50°. In the twelfth Se site, Se is bonded to six Ce atoms to form a mixture of distorted face, edge, and corner-sharing SeCe6 octahedra. The corner-sharing octahedra tilt angles range from 17–50°.