DOE OSTI2020
K4SnO4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.72–2.81 Å. In the second K1+ site, K1+ is bonded to five O2- atoms to form distorted KO5 trigonal bipyramids that share corners with three equivalent KO5 square pyramids, corners with two equivalent KO4 tetrahedra, corners with three equivalent SnO4 tetrahedra, edges with three equivalent KO5 square pyramids, an edgeedge with one SnO4 tetrahedra, and edges with two equivalent KO5 trigonal bipyramids. There are a spread of K–O bond distances ranging from 2.68–2.88 Å. In the third K1+ site, K1+ is bonded to four O2- atoms to form distorted KO4 tetrahedra that share corners with two equivalent KO5 square pyramids, corners with four equivalent SnO4 tetrahedra, corners with two equivalent KO5 trigonal bipyramids, and edges with two equivalent KO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.66–2.71 Å. In the fourth K1+ site, K1+ is bonded to five O2- atoms to form distorted KO5 square pyramids that share a cornercorner with one SnO4 tetrahedra, corners with two equivalent KO4 tetrahedra, corners with three equivalent KO5 trigonal bipyramids, edges with two equivalent KO5 square pyramids, edges with two equivalent SnO4 tetrahedra, and edges with three equivalent KO5 trigonal bipyramids. There are a spread of K–O bond distances ranging from 2.76–2.93 Å. Sn4+ is bonded to four O2- atoms to form SnO4 tetrahedra that share a cornercorner with one KO5 square pyramid, corners with four equivalent KO4 tetrahedra, corners with three equivalent KO5 trigonal bipyramids, edges with two equivalent KO5 square pyramids, and an edgeedge with one KO5 trigonal bipyramid. There are one shorter (1.99 Å) and three longer (2.01 Å) Sn–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five K1+ and one Sn4+ atom to form a mixture of edge and corner-sharing OK5Sn octahedra. The corner-sharing octahedra tilt angles range from 10–30°. In the second O2- site, O2- is bonded to five K1+ and one Sn4+ atom to form a mixture of distorted edge and corner-sharing OK5Sn octahedra. The corner-sharing octahedra tilt angles range from 10–30°. In the third O2- site, O2- is bonded to five K1+ and one Sn4+ atom to form a mixture of distorted edge and corner-sharing OK5Sn octahedra. The corner-sharing octahedra tilt angles range from 17–19°. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three K1+ and one Sn4+ atom.