DOI: 10.17188/1716346
title: Materials Data on Ca4Tl3O9 by Materials Project

description: Ca4Tl3O9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.32–2.81 Å. In the second Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with three TlO6 octahedra, edges with three equivalent TlO6 octahedra, and edges with four equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 7–62°. There are a spread of Ca–O bond distances ranging from 2.27–2.43 Å. There are two inequivalent Tl sites. In the first Tl site, Tl is bonded to six O atoms to form TlO6 octahedra that share a cornercorner with one CaO6 octahedra, corners with two equivalent TlO6 octahedra, and edges with five equivalent TlO6 octahedra. The corner-sharing octahedra tilt angles range from 0–62°. There are a spread of Tl–O bond distances ranging from 2.11–2.44 Å. In the second Tl site, Tl is bonded to six O atoms to form TlO6 octahedra that share corners with four equivalent CaO6 octahedra, edges with two equivalent TlO6 octahedra, and edges with six equivalent CaO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are two shorter (2.22 Å) and four longer (2.39 Å) Tl–O bond lengths. There are five inequivalent O sites. In the first O site, O is bonded to two equivalent Ca and three equivalent Tl atoms to form distorted OCa2Tl3 trigonal bipyramids that share corners with two equivalent OCa2Tl4 octahedra, corners with five equivalent OCa3Tl tetrahedra, corners with two equivalent OCa4Tl trigonal bipyramids, edges with three equivalent OCa2Tl4 octahedra, an edgeedge with one OCa3Tl tetrahedra, and edges with five OCa4Tl trigonal bipyramids. The corner-sharing octahedral tilt angles are 8°. In the second O site, O is bonded to three equivalent Ca and two equivalent Tl atoms to form OCa3Tl2 square pyramids that share corners with two equivalent OCa3Tl2 square pyramids, corners with three equivalent OCa3Tl tetrahedra, corners with four equivalent OCa4Tl trigonal bipyramids, edges with five equivalent OCa3Tl2 square pyramids, and edges with three equivalent OCa4Tl trigonal bipyramids. In the third O site, O is bonded to three Ca and one Tl atom to form OCa3Tl tetrahedra that share corners with three equivalent OCa3Tl2 square pyramids, corners with two equivalent OCa3Tl tetrahedra, corners with nine OCa4Tl trigonal bipyramids, edges with two equivalent OCa2Tl4 octahedra, and edges with two OCa4Tl trigonal bipyramids. In the fourth O site, O is bonded to four Ca and one Tl atom to form distorted OCa4Tl trigonal bipyramids that share corners with two equivalent OCa2Tl4 octahedra, corners with four equivalent OCa3Tl2 square pyramids, corners with four equivalent OCa3Tl tetrahedra, corners with three OCa2Tl3 trigonal bipyramids, edges with three equivalent OCa3Tl2 square pyramids, an edgeedge with one OCa3Tl tetrahedra, and edges with three OCa4Tl trigonal bipyramids. The corner-sharing octahedral tilt angles are 44°. In the fifth O site, O is bonded to two equivalent Ca and four equivalent Tl atoms to form OCa2Tl4 octahedra that share corners with eight OCa4Tl trigonal bipyramids, edges with two equivalent OCa2Tl4 octahedra, edges with four equivalent OCa3Tl tetrahedra, and edges with six equivalent OCa2Tl3 trigonal bipyramids.