Materials Data on NaTa3O8 by Materials Project

Abstract

NaTaO3Ta2O5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Na1+ is bonded to eight O2- atoms to form distorted NaO8 hexagonal bipyramids that share edges with two equivalent NaO8 hexagonal bipyramids, edges with two equivalent TaO8 hexagonal bipyramids, and edges with eight equivalent TaO7 pentagonal bipyramids. There are four shorter (2.55 Å) and four longer (2.71 Å) Na–O bond lengths. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to seven O2- atoms to form distorted TaO7 pentagonal bipyramids that share corners with two equivalent TaO8 hexagonal bipyramids, corners with two equivalent TaO7 pentagonal bipyramids, edges with two equivalent TaO8 hexagonal bipyramids, edges with four equivalent NaO8 hexagonal bipyramids, and edges with two equivalent TaO7 pentagonal bipyramids. There are a spread of Ta–O bond distances ranging from 1.95–2.35 Å. In the second Ta5+ site, Ta5+ is bonded to eight O2- atoms to form distorted TaO8 hexagonal bipyramids that share corners with four equivalent TaO7 pentagonal bipyramids, edges with two equivalent NaO8 hexagonal bipyramids, edges with two equivalent TaO8 hexagonal bipyramids, and edges with four equivalent TaO7 pentagonal bipyramids. There are four shorter (2.09 Å) and four longer (2.10 Å) Ta–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+ and three Ta5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms.