DOE OSTI2020
K4Mg(MoO4)3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with two equivalent KO6 octahedra and corners with six MoO4 tetrahedra. The corner-sharing octahedral tilt angles are 73°. There are a spread of K–O bond distances ranging from 2.73–2.96 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.62–2.93 Å. In the third K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.76–3.16 Å. In the fourth K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share a cornercorner with one KO6 octahedra, corners with six MoO4 tetrahedra, and an edgeedge with one KO6 octahedra. The corner-sharing octahedral tilt angles are 73°. There are a spread of K–O bond distances ranging from 2.68–2.84 Å. In the fifth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.80–3.10 Å. Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with five MoO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.19 Å. There are three inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with three KO6 octahedra and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 44–63°. There are a spread of Mo–O bond distances ranging from 1.78–1.83 Å. In the second Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with four KO6 octahedra and a cornercorner with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 33–57°. There are a spread of Mo–O bond distances ranging from 1.78–1.83 Å. In the third Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two KO6 octahedra and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Mo–O bond distances ranging from 1.79–1.82 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Mg2+, and one Mo6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+, one Mg2+, and one Mo6+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three K1+ and one Mo6+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Mg2+, and one Mo6+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one Mo6+ atom. In the tenth O2- site, O2- is bonded to three K1+ and one Mo6+ atom to form distorted edge-sharing OK3Mo trigonal pyramids. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one Mo6+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Mg2+, and one Mo6+ atom.