Materials Data on K3AlSe3 by Materials Project
K3AlSe3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.40–4.00 Å. In the second K1+ site, K1+ is bonded to five Se2- atoms to form distorted KSe5 trigonal bipyramids that share corners with four equivalent AlSe4 tetrahedra, corners with two equivalent KSe5 trigonal bipyramids, an edgeedge with one AlSe4 tetrahedra, and an edgeedge with one KSe5 trigonal bipyramid. There are a spread of K–Se bond distances ranging from 3.29–3.51 Å. In the third K1+ site, K1+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of K–Se bond distances ranging from 3.27–3.85 Å. Al3+ is bonded to four Se2- atoms to form AlSe4 tetrahedra that share corners with four equivalent KSe5 trigonal bipyramids, an edgeedge with one AlSe4 tetrahedra, and an edgeedge with one KSe5 trigonal bipyramid. There are a spread of Al–Se bond distances ranging from 2.38–2.48 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 2-coordinate geometry to five K1+ and two equivalent Al3+ atoms. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to six K1+ and one Al3+ atom. In the third Se2- site, Se2- is bonded in a 1-coordinate geometry to seven K1+ and one Al3+ atom.