DOE OSTI2020
KNbW2O9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of K–O bond distances ranging from 3.23–3.51 Å. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share edges with two equivalent NbO6 octahedra, edges with ten WO6 octahedra, and faces with two equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.27–3.49 Å. In the third 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 3.06–3.29 Å. There are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four WO6 octahedra. The corner-sharing octahedra tilt angles range from 8–36°. There are a spread of Nb–O bond distances ranging from 1.83–2.13 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three NbO6 octahedra, corners with three WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–39°. There are a spread of Nb–O bond distances ranging from 1.83–2.13 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three NbO6 octahedra and corners with three WO6 octahedra. The corner-sharing octahedra tilt angles range from 8–39°. There are a spread of Nb–O bond distances ranging from 1.83–2.13 Å. There are six inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with three NbO6 octahedra, corners with three WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–35°. There are a spread of W–O bond distances ranging from 1.84–2.12 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two NbO6 octahedra, corners with four WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–33°. There are a spread of W–O bond distances ranging from 1.84–2.12 Å. In the third W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with five WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–34°. There are a spread of W–O bond distances ranging from 1.84–2.12 Å. In the fourth W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with five WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–36°. There are a spread of W–O bond distances ranging from 1.84–2.11 Å. In the fifth W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with two NbO6 octahedra, corners with four WO6 octahedra, and edges with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–34°. There are a spread of W–O bond distances ranging from 1.84–2.11 Å. In the sixth W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five WO6 octahedra. The corner-sharing octahedra tilt angles range from 4–33°. There are a spread of W–O bond distances ranging from 1.84–2.11 Å. There are twenty-seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Nb5+, and one W6+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Nb5+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Nb5+, and one W6+ atom. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Nb5+, and one W6+ atom. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+, one Nb5+, and one W6+ atom. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+ and two W6+ atoms. In the twentieth O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the twenty-first O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one W6+ atom. In the twenty-third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the twenty-fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two W6+ atoms. In the twenty-sixth O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms. In the twenty-seventh O2- site, O2- is bonded in a linear geometry to two equivalent W6+ atoms.