Materials Data on Ca2CdAs2 by Materials Project

Abstract

Ca2CdAs2 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to five As3- atoms to form CaAs5 square pyramids that share corners with eleven CaAs5 square pyramids, corners with four equivalent CdAs4 tetrahedra, edges with four CaAs5 square pyramids, and edges with three equivalent CdAs4 tetrahedra. There are a spread of Ca–As bond distances ranging from 2.98–3.15 Å. In the second Ca2+ site, Ca2+ is bonded to five As3- atoms to form CaAs5 square pyramids that share corners with eleven CaAs5 square pyramids, corners with two equivalent CdAs4 tetrahedra, edges with six CaAs5 square pyramids, and edges with four equivalent CdAs4 tetrahedra. There are a spread of Ca–As bond distances ranging from 2.96–3.11 Å. Cd2+ is bonded to four As3- atoms to form CdAs4 tetrahedra that share corners with six CaAs5 square pyramids, corners with four equivalent CdAs4 tetrahedra, and edges with seven CaAs5 square pyramids. There are a spread of Cd–As bond distances ranging from 2.68–2.86 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to six Ca2+ and two equivalent Cd2+ atoms. In the second As3- site, As3- is bonded to four Ca2+ and two equivalent Cd2+ atoms to form a mixture of distorted edge and corner-sharing AsCa4Cd2 octahedra. The corner-sharing octahedral tilt angles are 77°.