Materials Data on KCaEr2CuS5 by Materials Project

KCaEr2CuS5 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to eight S2- atoms. There are a spread of K–S bond distances ranging from 3.12–3.84 Å. Ca2+ is bonded to six S2- atoms to form CaS6 octahedra that share corners with four equivalent ErS6 octahedra, corners with two equivalent CuS4 tetrahedra, edges with two equivalent CaS6 octahedra, and edges with six equivalent ErS6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are two shorter (2.77 Å) and four longer (2.89 Å) Ca–S bond lengths. Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share a cornercorner with one ErS6 octahedra, corners with two equivalent CaS6 octahedra, edges with three equivalent CaS6 octahedra, edges with four equivalent ErS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 5–41°. There are a spread of Er–S bond distances ranging from 2.67–2.81 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent CaS6 octahedra, corners with two equivalent CuS4 tetrahedra, and edges with four equivalent ErS6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are two shorter (2.33 Å) and two longer (2.36 Å) Cu–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded to one K1+, two equivalent Ca2+, and three equivalent Er3+ atoms to form distorted SKCa2Er3 square pyramids that share corners with four equivalent SK2CaEr2Cu octahedra, corners with three equivalent SKCa2Er3 square pyramids, edges with five equivalent SK2CaEr2Cu octahedra, and edges with five equivalent SKCa2Er3 square pyramids. The corner-sharing octahedra tilt angles range from 7–41°. In the second S2- site, S2- is bonded to two equivalent K1+, one Ca2+, two equivalent Er3+, and one Cu1+ atom to form distorted SK2CaEr2Cu octahedra that share corners with three equivalent SK2CaEr2Cu octahedra, corners with four equivalent SKCa2Er3 square pyramids, edges with two equivalent SK2CaEr2Cu octahedra, edges with five equivalent SKCa2Er3 square pyramids, and a faceface with one SK2CaEr2Cu octahedra. The corner-sharing octahedra tilt angles range from 0–65°. In the third S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent K1+, two equivalent Er3+, and two equivalent Cu1+ atoms.