Materials Data on Pr3TaO7 by Materials Project

Abstract

Pr3TaO7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.78 Å) Pr–O bond lengths. In the second Pr3+ site, Pr3+ is bonded to seven O2- atoms to form distorted PrO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, corners with three equivalent PrO7 pentagonal bipyramids, edges with two equivalent TaO6 octahedra, and edges with two equivalent PrO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Pr–O bond distances ranging from 2.33–2.74 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent PrO7 pentagonal bipyramids, and edges with four equivalent PrO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 29°. There are two shorter (2.00 Å) and four longer (2.01 Å) Ta–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Pr3+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to four Pr3+ atoms to form a mixture of edge and corner-sharing OPr4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Pr3+ and one Ta5+ atom.