Materials Data on KCa2Mg2V3O12 by Materials Project
Ca2KMg2V3O12 is Esseneite-derived structured and crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.62 Å) and four longer (2.69 Å) K–O bond lengths. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.44–2.69 Å. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six VO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.15 Å. There are two inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to four equivalent O2- atoms to form VO4 tetrahedra that share corners with four equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 48°. All V–O bond lengths are 1.75 Å. In the second V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four equivalent MgO6 octahedra. The corner-sharing octahedra tilt angles range from 43–49°. There is two shorter (1.74 Å) and two longer (1.77 Å) V–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to one K1+, one Ca2+, one Mg2+, and one V5+ atom to form a mixture of distorted edge and corner-sharing OKCaMgV trigonal pyramids. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one K1+, one Ca2+, one Mg2+, and one V5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+, one Mg2+, and one V5+ atom.