Materials Data on Co2As by Materials Project
Co2As crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are six inequivalent Co+1.50+ sites. In the first Co+1.50+ site, Co+1.50+ is bonded in a 5-coordinate geometry to five As3- atoms. There are one shorter (2.27 Å) and four longer (2.51 Å) Co–As bond lengths. In the second Co+1.50+ site, Co+1.50+ is bonded to five As3- atoms to form distorted CoAs5 square pyramids that share corners with six CoAs5 square pyramids, corners with six CoAs4 tetrahedra, edges with two equivalent CoAs5 square pyramids, and edges with eight CoAs4 tetrahedra. There are one shorter (2.42 Å) and four longer (2.62 Å) Co–As bond lengths. In the third Co+1.50+ site, Co+1.50+ is bonded to five As3- atoms to form distorted CoAs5 square pyramids that share corners with eight CoAs5 square pyramids, corners with eight CoAs4 tetrahedra, edges with five equivalent CoAs5 square pyramids, and edges with five CoAs4 tetrahedra. There are a spread of Co–As bond distances ranging from 2.39–2.58 Å. In the fourth Co+1.50+ site, Co+1.50+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with four CoAs5 square pyramids, corners with twelve CoAs4 tetrahedra, edges with four equivalent CoAs5 square pyramids, and edges with two equivalent CoAs4 tetrahedra. There are two shorter (2.24 Å) and two longer (2.35 Å) Co–As bond lengths. In the fifth Co+1.50+ site, Co+1.50+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with six equivalent CoAs5 square pyramids, corners with four CoAs4 tetrahedra, edges with four CoAs5 square pyramids, and edges with four equivalent CoAs4 tetrahedra. There are two shorter (2.33 Å) and two longer (2.36 Å) Co–As bond lengths. In the sixth Co+1.50+ site, Co+1.50+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with six CoAs5 square pyramids, corners with seven CoAs4 tetrahedra, edges with five CoAs5 square pyramids, and edges with two equivalent CoAs4 tetrahedra. There are a spread of Co–As bond distances ranging from 2.25–2.36 Å. There are four inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to nine Co+1.50+ atoms. In the second As3- site, As3- is bonded in a 9-coordinate geometry to nine Co+1.50+ atoms. In the third As3- site, As3- is bonded in a 9-coordinate geometry to nine Co+1.50+ atoms. In the fourth As3- site, As3- is bonded in a 9-coordinate geometry to nine Co+1.50+ atoms.