DOE OSTI2020
CeTa7O19 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ce3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.46–2.71 Å. There are five inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ta–O bond distances ranging from 1.93–2.51 Å. In the second Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ta–O bond distances ranging from 1.93–2.51 Å. In the third Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ta–O bond distances ranging from 1.93–2.51 Å. In the fourth Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ta–O bond distances ranging from 1.93–2.51 Å. In the fifth Ta5+ site, Ta5+ is bonded in an octahedral geometry to six O2- atoms. There are three shorter (2.01 Å) and three longer (2.02 Å) Ta–O bond lengths. There are nineteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. The O–Ta bond length is 2.00 Å. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. The O–Ta bond length is 2.51 Å. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. The O–Ta bond length is 1.99 Å. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Ta5+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. The O–Ta bond length is 2.04 Å. In the ninth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. In the twelfth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ce3+ and two Ta5+ atoms. The O–Ta bond length is 2.04 Å. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ce3+ and three Ta5+ atoms. The O–Ta bond length is 2.08 Å. In the fourteenth O2- site, O2- is bonded in a trigonal planar geometry to three Ta5+ atoms. The O–Ta bond length is 2.01 Å. In the fifteenth O2- site, O2- is bonded in a trigonal planar geometry to three Ta5+ atoms. In the sixteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ce3+ and three Ta5+ atoms. In the seventeenth O2- site, O2- is bonded in a linear geometry to two Ta5+ atoms. In the eighteenth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms. In the nineteenth O2- site, O2- is bonded in a linear geometry to two Ta5+ atoms. The O–Ta bond length is 1.93 Å.