Materials Data on KNaSe by Materials Project
KNaSe crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded to five equivalent Se2- atoms to form distorted KSe5 trigonal bipyramids that share corners with eight equivalent NaSe4 tetrahedra, corners with eight equivalent KSe5 trigonal bipyramids, edges with six equivalent NaSe4 tetrahedra, and edges with six equivalent KSe5 trigonal bipyramids. There are a spread of K–Se bond distances ranging from 3.34–3.48 Å. Na1+ is bonded to four equivalent Se2- atoms to form NaSe4 tetrahedra that share corners with eight equivalent NaSe4 tetrahedra, corners with eight equivalent KSe5 trigonal bipyramids, edges with two equivalent NaSe4 tetrahedra, and edges with six equivalent KSe5 trigonal bipyramids. There are a spread of Na–Se bond distances ranging from 2.96–3.01 Å. Se2- is bonded in a 9-coordinate geometry to five equivalent K1+ and four equivalent Na1+ atoms.