How are centrosymmetric and noncentrosymmetric structures achieved in uranyl borates?
Four uranyl borates, UO(2)B(2)O(4) (UBO-1), alpha-(UO(2))(2)[B(9)O(14)(OH)(4)] (UBO-2), beta-(UO(2))(2)[B(9)O(14)(OH)(4)] (UBO-3), and (UO(2))(2)[B(13)O(20)(OH)(3)].1.25H(2)O (UBO-4), have been prepared from boric acid fluxes at 190 degrees C. UBO-3 and UBO-4 are centrosymmetric, whereas UBO-1 and UBO-2 are noncentrosymmetric (chiral and polar). These uranyl borates possess layered structures constructed from UO(8) hexagonal bipyramids, BO(3) triangles, and BO(4) tetrahedra. In the case of UBO-4, clusters of BO(3) triangles link the layers together to form open slabs with a thickness of almost 2 nm. The ability of uranyl borates to use very similar layers to yield both centrosymmetric and noncentrosymmetric layers is detailed in this work.
Department of Civil Engineering and Geological Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Shuao
S
Wang
Evgeny V
EV
Alekseev
Jared T
JT
Stritzinger
Wulf
W
Depmeier
Thomas E
TE
Albrecht-Schmitt