DOE OSTI2020
Tb2B4O9 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Tb–O bond distances ranging from 2.31–2.80 Å. In the second Tb3+ site, Tb3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Tb–O bond distances ranging from 2.25–2.81 Å. In the third Tb3+ site, Tb3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Tb–O bond distances ranging from 2.30–2.73 Å. In the fourth Tb3+ site, Tb3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Tb–O bond distances ranging from 2.28–2.78 Å. In the fifth Tb3+ site, Tb3+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Tb–O bond distances ranging from 2.29–2.88 Å. There are ten inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.53 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.52 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.50 Å. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.40–1.59 Å. In the fifth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.50 Å. In the sixth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There is three shorter (1.49 Å) and one longer (1.52 Å) B–O bond length. In the seventh B3+ site, B3+ is bonded to four O2- atoms to form a mixture of edge and corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.51 Å. In the eighth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.42–1.52 Å. In the ninth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.50 Å. In the tenth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.52 Å. There are twenty-three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Tb3+ and one B3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Tb3+ and one B3+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Tb3+ and two equivalent B3+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Tb3+ and two B3+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Tb3+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to three Tb3+ and one B3+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to three Tb3+ and one B3+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to one Tb3+ and two equivalent B3+ atoms. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to one Tb3+ and two B3+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Tb3+ and one B3+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Tb3+ and two B3+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Tb3+ and two B3+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the nineteenth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Tb3+ and two B3+ atoms. In the twentieth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Tb3+ and two B3+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Tb3+ and two equivalent B3+ atoms.