Materials Data on NaAsSe2 by Materials Project

Abstract

NaAsSe2 is Caswellsilverite-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with six equivalent NaSe6 octahedra, edges with four equivalent NaSe6 octahedra, and edges with eight equivalent AsSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.78 Å) and four longer (2.83 Å) Na–Se bond lengths. As3+ is bonded to six Se2- atoms to form AsSe6 octahedra that share corners with six equivalent AsSe6 octahedra, edges with four equivalent AsSe6 octahedra, and edges with eight equivalent NaSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.78 Å) and four longer (2.83 Å) As–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Na1+ and four equivalent As3+ atoms to form a mixture of corner and edge-sharing SeNa2As4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second Se2- site, Se2- is bonded to four equivalent Na1+ and two equivalent As3+ atoms to form SeNa4As2 octahedra that share corners with six equivalent SeNa4As2 octahedra and edges with twelve SeNa2As4 octahedra. The corner-sharing octahedral tilt angles are 0°.