DOE OSTI2020
Ca21(Cd2Bi9)2 is Magnesium tetraboride-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are twelve inequivalent Ca sites. In the first Ca site, Ca is bonded in a 9-coordinate geometry to two equivalent Cd and seven Bi atoms. Both Ca–Cd bond lengths are 3.50 Å. There are a spread of Ca–Bi bond distances ranging from 3.43–3.70 Å. In the second Ca site, Ca is bonded in a 5-coordinate geometry to two Cd and six Bi atoms. There are one shorter (3.44 Å) and one longer (3.75 Å) Ca–Cd bond lengths. There are a spread of Ca–Bi bond distances ranging from 3.24–3.64 Å. In the third Ca site, Ca is bonded in a 7-coordinate geometry to one Cd and six Bi atoms. The Ca–Cd bond length is 3.46 Å. There are a spread of Ca–Bi bond distances ranging from 3.23–3.47 Å. In the fourth Ca site, Ca is bonded in a 6-coordinate geometry to one Cd and six Bi atoms. The Ca–Cd bond length is 3.89 Å. There are a spread of Ca–Bi bond distances ranging from 3.12–3.43 Å. In the fifth Ca site, Ca is bonded in a 2-coordinate geometry to six Bi atoms. There are a spread of Ca–Bi bond distances ranging from 3.17–3.83 Å. In the sixth Ca site, Ca is bonded to six Bi atoms to form a mixture of distorted edge and corner-sharing CaBi6 octahedra. The corner-sharing octahedral tilt angles are 69°. There are a spread of Ca–Bi bond distances ranging from 3.30–3.54 Å. In the seventh Ca site, Ca is bonded in a 6-coordinate geometry to one Cd and six Bi atoms. The Ca–Cd bond length is 3.94 Å. There are a spread of Ca–Bi bond distances ranging from 3.17–3.52 Å. In the eighth Ca site, Ca is bonded in a 6-coordinate geometry to six Bi atoms. There are a spread of Ca–Bi bond distances ranging from 3.19–3.81 Å. In the ninth Ca site, Ca is bonded in a 6-coordinate geometry to two Cd and four Bi atoms. There are one shorter (3.39 Å) and one longer (3.41 Å) Ca–Cd bond lengths. There are a spread of Ca–Bi bond distances ranging from 3.13–3.52 Å. In the tenth Ca site, Ca is bonded in a 7-coordinate geometry to seven Bi atoms. There are a spread of Ca–Bi bond distances ranging from 3.15–3.88 Å. In the eleventh Ca site, Ca is bonded to six Bi atoms to form a mixture of distorted edge and corner-sharing CaBi6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Ca–Bi bond distances ranging from 3.18–3.46 Å. In the twelfth Ca site, Ca is bonded in a 6-coordinate geometry to two equivalent Cd and six Bi atoms. Both Ca–Cd bond lengths are 3.80 Å. There are a spread of Ca–Bi bond distances ranging from 3.37–3.63 Å. There are three inequivalent Cd sites. In the first Cd site, Cd is bonded in a 9-coordinate geometry to two equivalent Ca, one Cd, and four Bi atoms. The Cd–Cd bond length is 2.92 Å. There are a spread of Cd–Bi bond distances ranging from 3.02–3.14 Å. In the second Cd site, Cd is bonded in a 7-coordinate geometry to two equivalent Ca, one Cd, and four Bi atoms. There are a spread of Cd–Bi bond distances ranging from 2.97–3.01 Å. In the third Cd site, Cd is bonded in a 11-coordinate geometry to seven Ca and four Bi atoms. There are a spread of Cd–Bi bond distances ranging from 2.98–3.10 Å. There are fourteen inequivalent Bi sites. In the first Bi site, Bi is bonded in a 10-coordinate geometry to six Ca, two equivalent Cd, and one Bi atom. The Bi–Bi bond length is 3.44 Å. In the second Bi site, Bi is bonded in a 2-coordinate geometry to seven Ca and one Bi atom. The Bi–Bi bond length is 3.08 Å. In the third Bi site, Bi is bonded in a 7-coordinate geometry to eight Ca atoms. In the fourth Bi site, Bi is bonded in a 7-coordinate geometry to six Ca, one Cd, and one Bi atom. The Bi–Bi bond length is 3.42 Å. In the fifth Bi site, Bi is bonded in a 10-coordinate geometry to eight Ca and two Bi atoms. The Bi–Bi bond length is 3.14 Å. In the sixth Bi site, Bi is bonded in a 9-coordinate geometry to six Ca and three Cd atoms. In the seventh Bi site, Bi is bonded in a 2-coordinate geometry to eight Ca and two Bi atoms. The Bi–Bi bond length is 3.10 Å. In the eighth Bi site, Bi is bonded in a 8-coordinate geometry to six Ca and two Cd atoms. In the ninth Bi site, Bi is bonded in a 8-coordinate geometry to seven Ca and one Cd atom. In the tenth Bi site, Bi is bonded in a 8-coordinate geometry to eight Ca atoms. In the eleventh Bi site, Bi is bonded in a 7-coordinate geometry to five Ca, one Cd, and one Bi atom. The Bi–Bi bond length is 3.04 Å. In the twelfth Bi site, Bi is bonded in a 7-coordinate geometry to six Ca and one Cd atom. In the thirteenth Bi site, Bi is bonded in a 8-coordinate geometry to eight Ca atoms. In the fourteenth Bi site, Bi is bonded in a 10-coordinate geometry to seven Ca and one Cd atom.