DOE OSTI2020
Co2SiO4 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with eight CoO6 octahedra, corners with four SiO4 tetrahedra, edges with two CoO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Co–O bond distances ranging from 2.09–2.26 Å. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO6 octahedra, corners with two SiO4 tetrahedra, edges with four CoO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Co–O bond distances ranging from 2.10–2.18 Å. In the third Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with eight CoO6 octahedra, corners with four SiO4 tetrahedra, edges with two CoO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Co–O bond distances ranging from 2.07–2.25 Å. In the fourth Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with eight CoO6 octahedra, corners with four SiO4 tetrahedra, edges with two CoO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Co–O bond distances ranging from 2.08–2.25 Å. In the fifth Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO6 octahedra, corners with two SiO4 tetrahedra, edges with four CoO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–63°. There are a spread of Co–O bond distances ranging from 2.10–2.19 Å. In the sixth Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with eight CoO6 octahedra, corners with four SiO4 tetrahedra, edges with two CoO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Co–O bond distances ranging from 2.07–2.28 Å. In the seventh Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO6 octahedra, corners with two SiO4 tetrahedra, edges with four CoO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Co–O bond distances ranging from 2.10–2.20 Å. In the eighth Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO6 octahedra, corners with two SiO4 tetrahedra, edges with four CoO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–63°. There are a spread of Co–O bond distances ranging from 2.03–2.18 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six CoO6 octahedra and edges with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–61°. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six CoO6 octahedra and edges with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–61°. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six CoO6 octahedra and edges with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 54–62°. There are a spread of Si–O bond distances ranging from 1.64–1.69 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six CoO6 octahedra and edges with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Si–O bond distances ranging from 1.64–1.68 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Co2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Co2+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Co2+ and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Co2+ and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co2+ and one Si4+ atom.