Materials Data on Na3Ca2TaO6 by Materials Project

Abstract

Na3Ca2TaO6 is Caswellsilverite-derived structured and crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent CaO6 octahedra, edges with two equivalent TaO6 octahedra, edges with four equivalent CaO6 octahedra, and edges with six equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are four shorter (2.39 Å) and two longer (2.76 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with two equivalent CaO6 octahedra, corners with two equivalent TaO6 octahedra, edges with two equivalent TaO6 octahedra, edges with five NaO6 octahedra, and edges with five equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 3–17°. There are a spread of Na–O bond distances ranging from 2.41–2.60 Å. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with four NaO6 octahedra, edges with two equivalent CaO6 octahedra, edges with three equivalent TaO6 octahedra, and edges with seven NaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–18°. There are a spread of Ca–O bond distances ranging from 2.33–2.38 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six NaO6 octahedra, edges with six NaO6 octahedra, and edges with six equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are two shorter (2.03 Å) and four longer (2.04 Å) Ta–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three Na1+, two equivalent Ca2+, and one Ta5+ atom to form a mixture of distorted edge and corner-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedra tilt angles range from 0–12°. In the second O2- site, O2- is bonded to three Na1+, two equivalent Ca2+, and one Ta5+ atom to form a mixture of distorted edge and corner-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedra tilt angles range from 2–12°.