Materials Data on BaCaV2O7 by Materials Project
BaCaV2O7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.69–3.25 Å. Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with four VO4 tetrahedra, edges with two equivalent CaO6 pentagonal pyramids, and an edgeedge with one VO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.46 Å. There are two inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids and a cornercorner with one VO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.69–1.85 Å. In the second V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids, a cornercorner with one VO4 tetrahedra, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of V–O bond distances ranging from 1.68–1.82 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ca2+, and one V5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Ba2+ and one V5+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one Ba2+ and one V5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two equivalent Ca2+, and one V5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two V5+ atoms.