DOI: 10.17188/1750943
title: Materials Data on Ca8(DySe4)3 by Materials Project

description: Ca8(DySe4)3 crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are four inequivalent Ca sites. In the first Ca site, Ca is bonded to six Se atoms to form CaSe6 octahedra that share corners with five equivalent CaSe6 octahedra, edges with two equivalent DySe6 octahedra, and edges with ten CaSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ca–Se bond distances ranging from 2.90–2.98 Å. In the second Ca site, Ca is bonded to six Se atoms to form CaSe6 octahedra that share a cornercorner with one DySe6 octahedra, corners with five CaSe6 octahedra, and edges with twelve CaSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Ca–Se bond distances ranging from 2.94–3.06 Å. In the third Ca site, Ca is bonded to six Se atoms to form CaSe6 octahedra that share a cornercorner with one DySe6 octahedra, corners with five CaSe6 octahedra, edges with four CaSe6 octahedra, and edges with six DySe6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of Ca–Se bond distances ranging from 2.91–3.05 Å. In the fourth Ca site, Ca is bonded to six Se atoms to form CaSe6 octahedra that share a cornercorner with one DySe6 octahedra, corners with five equivalent CaSe6 octahedra, edges with two equivalent DySe6 octahedra, and edges with ten CaSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Ca–Se bond distances ranging from 2.94–3.02 Å. There are two inequivalent Dy sites. In the first Dy site, Dy is bonded to six Se atoms to form DySe6 octahedra that share corners with two CaSe6 octahedra, corners with four equivalent DySe6 octahedra, edges with two equivalent DySe6 octahedra, and edges with eight CaSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of Dy–Se bond distances ranging from 2.77–3.00 Å. In the second Dy site, Dy is bonded to six Se atoms to form DySe6 octahedra that share corners with two equivalent CaSe6 octahedra, corners with four equivalent DySe6 octahedra, edges with four equivalent CaSe6 octahedra, and edges with four equivalent DySe6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.91 Å) and four longer (2.94 Å) Dy–Se bond lengths. There are seven inequivalent Se sites. In the first Se site, Se is bonded to three Ca and three Dy atoms to form SeCa3Dy3 octahedra that share corners with six SeCa3Dy3 octahedra, edges with four SeCa6 octahedra, and edges with four equivalent SeCa3Dy2 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. In the second Se site, Se is bonded to six Ca atoms to form SeCa6 octahedra that share corners with five SeCa6 octahedra, edges with ten SeCa3Dy3 octahedra, and edges with two equivalent SeCa3Dy2 square pyramids. The corner-sharing octahedra tilt angles range from 0–1°. In the third Se site, Se is bonded to three Ca and two equivalent Dy atoms to form SeCa3Dy2 square pyramids that share a cornercorner with one SeCa6 octahedra, corners with four equivalent SeCa3Dy2 square pyramids, and edges with eight SeCa3Dy3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth Se site, Se is bonded to six Ca atoms to form SeCa6 octahedra that share corners with six SeCa3Dy3 octahedra and edges with twelve SeCa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth Se site, Se is bonded to five Ca and one Dy atom to form SeCa5Dy octahedra that share corners with five SeCa6 octahedra, edges with ten SeCa3Dy3 octahedra, and edges with two equivalent SeCa3Dy2 square pyramids. The corner-sharing octahedra tilt angles range from 0–4°. In the sixth Se site, Se is bonded to six Ca atoms to form SeCa6 octahedra that share corners with four equivalent SeCa6 octahedra, corners with two equivalent SeCa3Dy2 square pyramids, and edges with twelve SeCa6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh Se site, Se is bonded in a square co-planar geometry to one Ca and three Dy atoms.