Materials Data on KNaAl2As2O9 by Materials Project

Dataset · Sat Jan 12 04:00:00 EST 2019

DOI:https://doi.org/10.17188/1704922· OSTI ID:1704922

KNaAl2As2O9 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded to seven O2- atoms to form distorted KO7 pentagonal bipyramids that share corners with three AlO6 octahedra, corners with four equivalent KO7 pentagonal bipyramids, corners with six AsO4 tetrahedra, and an edgeedge with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 61–73°. There are a spread of K–O bond distances ranging from 2.67–3.09 Å. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.30–2.90 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share a cornercorner with one KO7 pentagonal bipyramid, corners with five AsO4 tetrahedra, edges with two equivalent AlO6 octahedra, and an edgeedge with one KO7 pentagonal bipyramid. There are a spread of Al–O bond distances ranging from 1.84–2.10 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent KO7 pentagonal bipyramids, corners with four AsO4 tetrahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–1.96 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four AlO6 octahedra and corners with four equivalent KO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of As–O bond distances ranging from 1.67–1.77 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with five AlO6 octahedra and corners with two equivalent KO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 46–57°. There are a spread of As–O bond distances ranging from 1.68–1.75 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one As5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, two Al3+, and one As5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+, two equivalent Na1+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Al3+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Na1+, and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and three Al3+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, one Al3+, and one As5+ atom.

• Research Organization: LBNL Materials Project; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Contributing Organization: The Materials Project; MIT; UC Berkeley; Duke; U Louvain
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1704922
• Report Number(s): mp-1203514
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Al-As-K-Na-O
KNaAl2As2O9
crystal structure