Materials Data on CaH2 by Materials Project

Abstract

CaH2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ca2+ is bonded in a 9-coordinate geometry to nine H1- atoms. There are a spread of Ca–H bond distances ranging from 2.24–2.62 Å. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded to four equivalent Ca2+ atoms to form HCa4 tetrahedra that share corners with eight equivalent HCa5 square pyramids, corners with eight equivalent HCa4 tetrahedra, edges with six equivalent HCa5 square pyramids, and edges with two equivalent HCa4 tetrahedra. In the second H1- site, H1- is bonded to five equivalent Ca2+ atoms to form distorted HCa5 square pyramids that share corners with eight equivalent HCa5 square pyramids, corners with eight equivalent HCa4 tetrahedra, edges with six equivalent HCa5 square pyramids, and edges with six equivalent HCa4 tetrahedra.