Materials Data on K2Al2Sb3 by Materials Project
K2Al2Sb3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Sb+2.67- atoms to form distorted KSb6 pentagonal pyramids that share corners with eight AlSb4 tetrahedra, edges with three KSb6 pentagonal pyramids, and edges with four AlSb4 tetrahedra. There are a spread of K–Sb bond distances ranging from 3.51–3.81 Å. In the second K1+ site, K1+ is bonded to six Sb+2.67- atoms to form distorted KSb6 pentagonal pyramids that share corners with eight AlSb4 tetrahedra, edges with three KSb6 pentagonal pyramids, and edges with four AlSb4 tetrahedra. There are a spread of K–Sb bond distances ranging from 3.49–3.93 Å. In the third K1+ site, K1+ is bonded in a 5-coordinate geometry to five Sb+2.67- atoms. There are a spread of K–Sb bond distances ranging from 3.59–3.82 Å. In the fourth K1+ site, K1+ is bonded in a 2-coordinate geometry to seven Sb+2.67- atoms. There are a spread of K–Sb bond distances ranging from 3.40–4.19 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four Sb+2.67- atoms to form AlSb4 tetrahedra that share corners with four KSb6 pentagonal pyramids, corners with five AlSb4 tetrahedra, edges with two KSb6 pentagonal pyramids, and an edgeedge with one AlSb4 tetrahedra. There are a spread of Al–Sb bond distances ranging from 2.70–2.81 Å. In the second Al3+ site, Al3+ is bonded to four Sb+2.67- atoms to form AlSb4 tetrahedra that share corners with four KSb6 pentagonal pyramids, corners with five AlSb4 tetrahedra, edges with two equivalent KSb6 pentagonal pyramids, and an edgeedge with one AlSb4 tetrahedra. There are a spread of Al–Sb bond distances ranging from 2.73–2.75 Å. In the third Al3+ site, Al3+ is bonded to four Sb+2.67- atoms to form AlSb4 tetrahedra that share corners with four KSb6 pentagonal pyramids, corners with five AlSb4 tetrahedra, edges with two KSb6 pentagonal pyramids, and an edgeedge with one AlSb4 tetrahedra. There are a spread of Al–Sb bond distances ranging from 2.70–2.76 Å. In the fourth Al3+ site, Al3+ is bonded to four Sb+2.67- atoms to form AlSb4 tetrahedra that share corners with four KSb6 pentagonal pyramids, corners with five AlSb4 tetrahedra, edges with two equivalent KSb6 pentagonal pyramids, and an edgeedge with one AlSb4 tetrahedra. There are a spread of Al–Sb bond distances ranging from 2.75–2.79 Å. There are six inequivalent Sb+2.67- sites. In the first Sb+2.67- site, Sb+2.67- is bonded in a 3-coordinate geometry to three K1+ and three Al3+ atoms. In the second Sb+2.67- site, Sb+2.67- is bonded to four K1+ and three Al3+ atoms to form distorted edge-sharing SbK4Al3 pentagonal bipyramids. In the third Sb+2.67- site, Sb+2.67- is bonded in a 6-coordinate geometry to four K1+ and three Al3+ atoms. In the fourth Sb+2.67- site, Sb+2.67- is bonded in a 7-coordinate geometry to four K1+, two Al3+, and one Sb+2.67- atom. The Sb–Sb bond length is 2.92 Å. In the fifth Sb+2.67- site, Sb+2.67- is bonded in a 3-coordinate geometry to five K1+ and three Al3+ atoms. In the sixth Sb+2.67- site, Sb+2.67- is bonded in a 7-coordinate geometry to four K1+, two Al3+, and one Sb+2.67- atom.