DOE OSTI2020
CaTi2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.39 Å. In the second Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.38 Å. There are four inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedra tilt angles range from 47–53°. There are a spread of Ti–O bond distances ranging from 1.96–2.21 Å. In the second Ti3+ site, Ti3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedra tilt angles range from 47–54°. There are a spread of Ti–O bond distances ranging from 2.01–2.17 Å. In the third Ti3+ site, Ti3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Ti–O bond distances ranging from 2.01–2.16 Å. In the fourth Ti3+ site, Ti3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–54°. There are a spread of Ti–O bond distances ranging from 1.97–2.20 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and three Ti3+ atoms to form distorted OCaTi3 trigonal pyramids that share corners with two equivalent OCa2Ti3 square pyramids, a cornercorner with one OCa2Ti3 trigonal bipyramid, corners with two equivalent OCaTi3 trigonal pyramids, edges with three OCa2Ti3 square pyramids, and edges with two equivalent OCa2Ti3 trigonal bipyramids. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti3+ atoms. In the fourth O2- site, O2- is bonded to one Ca2+ and three Ti3+ atoms to form distorted OCaTi3 trigonal pyramids that share corners with two equivalent OCa2Ti3 square pyramids, a cornercorner with one OCa2Ti3 trigonal bipyramid, corners with two equivalent OCaTi3 trigonal pyramids, edges with three OCa2Ti3 square pyramids, and edges with two equivalent OCa2Ti3 trigonal bipyramids. In the fifth O2- site, O2- is bonded to two equivalent Ca2+ and three Ti3+ atoms to form OCa2Ti3 square pyramids that share corners with two equivalent OCa2Ti3 trigonal bipyramids, corners with two equivalent OCaTi3 trigonal pyramids, edges with four OCa2Ti3 square pyramids, an edgeedge with one OCa2Ti3 trigonal bipyramid, and edges with three OCaTi3 trigonal pyramids. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Ti3+ atoms to form distorted OCa2Ti3 trigonal bipyramids that share corners with two equivalent OCa2Ti3 square pyramids, a cornercorner with one OCaTi3 trigonal pyramid, an edgeedge with one OCa2Ti3 square pyramid, edges with four OCa2Ti3 trigonal bipyramids, and edges with two equivalent OCaTi3 trigonal pyramids. In the seventh O2- site, O2- is bonded to two equivalent Ca2+ and three Ti3+ atoms to form OCa2Ti3 square pyramids that share corners with two equivalent OCa2Ti3 trigonal bipyramids, corners with two equivalent OCaTi3 trigonal pyramids, edges with four OCa2Ti3 square pyramids, an edgeedge with one OCa2Ti3 trigonal bipyramid, and edges with three OCaTi3 trigonal pyramids. In the eighth O2- site, O2- is bonded to two equivalent Ca2+ and three Ti3+ atoms to form distorted OCa2Ti3 trigonal bipyramids that share corners with two equivalent OCa2Ti3 square pyramids, a cornercorner with one OCaTi3 trigonal pyramid, an edgeedge with one OCa2Ti3 square pyramid, edges with four OCa2Ti3 trigonal bipyramids, and edges with two equivalent OCaTi3 trigonal pyramids.