Materials Data on Na(VSe2)2 by Materials Project

Abstract

Na(VSe2)2 is MAX Phase-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Na(VSe2)2 sheets oriented in the (0, 0, 1) direction. Na1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are three shorter (2.99 Å) and three longer (3.00 Å) Na–Se bond lengths. There are two inequivalent V+3.50+ sites. In the first V+3.50+ site, V+3.50+ is bonded to six Se2- atoms to form edge-sharing VSe6 octahedra. There are three shorter (2.52 Å) and three longer (2.59 Å) V–Se bond lengths. In the second V+3.50+ site, V+3.50+ is bonded to six Se2- atoms to form edge-sharing VSe6 octahedra. There are three shorter (2.52 Å) and three longer (2.59 Å) V–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Na1+ and three equivalent V+3.50+ atoms to form a mixture of face, edge, and corner-sharing SeNa3V3 octahedra. In the second Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent V+3.50+ atoms. In the third Se2- site, Se2- is bonded to three equivalent Na1+ and three equivalent V+3.50+ atoms to form a mixture of distorted face, edge, and corner-sharing SeNa3V3 pentagonal pyramids. The corner-sharing octahedral tilt angles are 41°. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent V+3.50+ atoms.