Materials Data on Sr4Ta2O9 by Materials Project

Abstract

Sr4Ta2O9 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six O2- atoms to form distorted SrO6 pentagonal pyramids that share corners with three equivalent SrO6 octahedra, corners with three equivalent TaO6 octahedra, a cornercorner with one SrO6 pentagonal pyramid, edges with three equivalent TaO6 octahedra, edges with two equivalent SrO6 pentagonal pyramids, and a faceface with one SrO6 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Sr–O bond distances ranging from 2.37–2.69 Å. In the second Sr2+ site, Sr2+ is bonded to six O2- atoms to form distorted SrO6 octahedra that share corners with six equivalent TaO6 octahedra, corners with three equivalent SrO6 pentagonal pyramids, edges with three equivalent SrO6 octahedra, and a faceface with one SrO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 40–55°. There are a spread of Sr–O bond distances ranging from 2.45–2.80 Å. Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with six equivalent SrO6 octahedra, corners with three equivalent SrO6 pentagonal pyramids, edges with three equivalent SrO6 pentagonal pyramids, and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 40–55°. There are a spread of Ta–O bond distances ranging from 1.91–2.18 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sr2+ and two equivalent Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSr2Ta2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Sr2+ and two equivalent Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSr2Ta2 trigonal pyramids. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Sr2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ta5+ atom.