Abstract
A series of f-block chromates, CsM(CrO4)2 (M = La, Pr, Nd, Sm, Eu; Am), were prepared revealing notable differences between the AmIII derivatives and their lanthanide analogs. While all compounds form similar layered structures, the americium compound exhibits polymorphism and adopts both a structure isomorphous with the early lanthanides as well as one that possesses lower symmetry. Both polymorphs are dark red and possess band gaps that are smaller than the LnIII compounds. In order to probe the origin of these differences, the electronic structure of α-CsSm(CrO4)2, α-CsEu(CrO4)2, and α-CsAm(CrO4)2 were studied using both a molecular cluster approach featuring hybrid density functional theory and QTAIM analysis and by the periodic LDA+GA and LDA+DMFT methods. Notably, the covalent contributions to bonding by the f orbitals were found to be more than twice as large in the AmIII chromate than in the SmIII and EuIII compounds, and even larger in magnitude than the Am-5f spin-orbit splitting in this system. Our analysis indicates also that the Am-O covalency in α-CsAm(CrO4)2 is driven by the degeneracy of the 5f and 2p orbitals, and not by orbital overlap.
| Original language | English |
|---|---|
| Pages (from-to) | 1674-1685 |
| Number of pages | 12 |
| Journal | Journal of the American Chemical Society |
| Volume | 140 |
| Issue number | 5 |
| DOIs | |
| State | Published - Feb 7 2018 |
| Externally published | Yes |
Funding
This work was supported as part of the Center for Actinide Science and Technology (CAST), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award no. DESC0016568. The 243Am was provided to Florida State University by the Isotope Development and Production for Research and Applications Program through the Radiochemical Engineering and Development Center at Oak Ridge National Laboratory. N.L., T.H., and V.D. were partially supported by the NSF grant DMR-1410132 and the National High Magnetic Field Laboratory. Y.Y. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, as part of the Computational Materials Science Program. X.D. was supported by the NSF grant DMR-1308141. We are grateful to the University of Manchester’s Computational Shared Facility for computational resources and associated support. Part of the calculations were performed utilizing the Extreme Science and Engineering Discovery Environment (XSEDE) by NSF under grant no. DMR170121. This work was supported as part of the Center for Actinide Science and Technology (CAST), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award no. DE-SC0016568. The 243Am was provided to Florida State University by the Isotope Development and Production for Research and Applications Program through the Radiochemical Engineering and Development Center at Oak Ridge National Laboratory. N.L., T.H., and V.D. were partially supported by the NSF grant DMR-1410132 and the National High Magnetic Field Laboratory. Y.Y. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, as part of the Computational Materials Science Program. X.D. was supported by the NSF grant DMR-1308141.